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Summary: In this work, an offset microstrip line coupled bilateral rectangular‐shaped dielectric resonator antenna (RDRA) is designed for broadband circular polarization (CP), which is fabricated and experimentally verified. The vertical microstrip is added in an offset position to generate orthogonal modes and the fundamental modes TEx111 and TEy111. The generation of orthogonal modes designates the antenna structure as a CP antenna with orthogonal modes. Moreover, the location of the microstrip feed arrangement is used to control the polarization state in the proposed work. In the proposed design, the simulated and hand‐measured input impedance bandwidth(|S11| ≤ −10 dB) obtained is 32.6% (3.53–4.9 GHz) and 33.2% (3.56–4.98 GHz), respectively, whereas the simulated and measured axial ratio (AR ≤ 3 dB) shows 16.1% (3.71–4.36 GHz) and 17.03% (3.7–4.39 GHz) of axial ratio bandwidth, respectively. This design shows a consistent radiation pattern and good average gain, with acceptable agreement between simulation and hand‐measured results. The simulated result shows 94% radiation efficiency in the working frequency range. [ABSTRACT FROM AUTHOR]

This research proposition introduces a novel microstrip antenna design that features triple notches for ultra-wideband (UWB) applications. The antenna, measuring 35.4 mm × 28.82 mm × 1.57 mm, incorporates rectangular and semi-circular slots, as well as a pentagonal stub. A modified U-shaped slot on the pentagonal stub creates one notched frequency band at 3.3–3.7 GHz. Additionally, two Split Ring Resonators (SRRs) are integrated into the antenna's rear surface, resulting in two more notched bands at 5.1–5.8 GHz and 7.1–7.8 GHz. Operating within a frequency range from 3 to 11.2 GHz with VSWR ≤ 2, the antenna effectively excludes the triple stop bands at 3.3–3.7 GHz (11.4%), 5.1–5.8 GHz (12.8%) and 7.1–7.8 GHz (9.4%). The proposed antenna has been successfully prototyped and verified. An extensive result analysis has been conducted, confirming that the developed antenna is suitable for application in a range of wireless systems. Moreover, the article includes the implementation of an equivalent circuit for the proposed antenna. [ABSTRACT FROM AUTHOR]

Due to the recent expansion in the generations of the communications systems, it is utmost priority to transmit a large amount of data over a wideband frequency spectrum. For this single ultra-wideband (UWB) antennas are the prime choice as compared to the multiple narrow band antennas. A modified pentagonal fractal patch antenna with a modified ground plane covering ultra-wideband has been proposed. The antenna has a compact size of 25 mm × 25 mm × 1.6 mm with peak gain of 2.2 dB. The UWB coverage of the design is achieved by implementing modified co-planar ground, modified fractal geometry and coplanar feed. The proposed design possesses the significant resonance and radiation performance with very compact size on low-cost substrate while covering the whole UWB. Finally, the simulated resonating and radiation characteristics have been validated with the measured characteristics of the fabricated prototype and the results are quite promising. [ABSTRACT FROM AUTHOR]

A circular ring structure monopolar printed antenna for Doppler and automotive radar systems (24 GHz) is designed with a size of 1.4λ0 × 1.4λ0 × 0.095λ0 mm3 observing |S11|> −20 dB, B.W. of 1.8 GHz and a peak gain of 5.1 dBi. This antenna upgraded initially into 2 × 1 and finally 4 × 1 array, having resonant frequencies at 24 GHz and 28 GHz, respectively. A peak gain of 7.12 and 7.16 dBi through 2 × 1 and 9 and 8.65 dBi through 4 × 1 array is observed at respective operating frequencies. Finally, the 4 × 1 array antenna with the tapered feed of size 4.4λ0 × 2.2λ0 × 0.095λ0 mm3 having |S11|≤ 40 dB at ISM-III (24 GHz) and |S11|≤ −30 dB at 5G (28 GHz) with B.W. of 0.77 GHz and 5.1 GHz, respectively, is proposed, qualifying the obtained measured results. Isolation between each antenna element for the 4 × 1 array is ≤ −20 dB with a maximum value of −65 dB. The ECC observed between antenna elements is less than 0.045 and DG is 10. An equivalent circuit is also evaluated for the proposed antenna. The quantification results present that the developed array antenna has excellent performance over the dual band. [ABSTRACT FROM AUTHOR]

This paper presents a circularly polarized (CP) monopulse slot array antenna based on gap waveguide (GWG) technology. The proposed monopulse antenna is composed of a 4 × 4 array antenna fed by the monopulse comparator network in a compact three-layer structure. To achieve a broad axial ratio (AR) bandwidth of right-handed circular polarization (RHCP) in the sum radiation pattern, a septum polarizer is used in the radiating aperture. Based on this approach, horizontal transition structures are used to excite the radiating array from the WR-28 waveguide to the GWG, which helps to reduce the reflection loss and expand the impedance bandwidth. Experimental results show that the impedance bandwidth is 30.5 GHz to 40 GHz, which is 27.1%. The 3 dB AR bandwidth is 31%. The measured null depth is −40 dB, and the maximum measured gain in the sum pattern is 22 dBi at 34 GHz, while the antenna efficiency is greater than 86%. The advantages of low loss, broad bandwidth, and compact structure make the proposed antenna a competitive candidate for millimeter-wave (mmWave) monopulse direction-finding applications. [ABSTRACT FROM AUTHOR]

In this paper, a definition for the active differential reflection coefficient of the differentially-fed antenna array is proposed. Each antenna is fed by the differential port with the equal-amplitude anti-phase signal input. According to the active reflection coefficient of the conventional single-ended antenna array, the active differential reflection coefficient definition of the differential antenna array is given and analyzed. It is derived that the active differential reflection coefficient of the differential port m is half of the active reflection coefficient sum for the single-ended port m+ and m−. In addition, the active differential impedance expression is also given. To verify the active differential reflection coefficient, a differential three-element microstrip patch antenna array was designed, fabricated, and measured. The experimental results validate the proposed theoretical analysis. This work will provide a new insight into the differential antenna array. [ABSTRACT FROM AUTHOR]

This study presents a substrate integrated waveguide (SIW) broadband circularly polarized (CP) high‐gain low‐profile magneto‐electric dipole antenna array. The antenna array is characterized by wide impedance bandwidth (IBW), novel CP operating principle, small form factor, and good radiation performance. First, the antenna element consists of a two‐layer dielectric substrate, two pairs of magneto‐electric dipoles, and a SIW cavity coupled and fed through a cross‐shaped rectangular slit. To achieve a wide CP bandwidth (BW), a pair of magneto‐electric dipoles is rectangularly chamfered and then an "L" type parasitic patch is introduced. The simulation results show that the antenna element has an axial ratio (AR) BW of 14.2% in the 31.48–36.16 GHz range, the IBW in the 29.08–35.98 GHz range is 21.2%, and the gain is greater than 8 dBic in all bands. The antenna exhibits stable patterns and wide overlap IBW (31.48–35.98 GHz). Then, a planar 2 × 2 antenna array fed by a one‐part‐four SIW power divider was designed, fabricated, and measured. The measured results show that the array has an ARBW of 14% in the range of 31.29−35.83 GHz, an IBW of 21.8% in the range of 29.28–35.83 GHz, and a peak gain of 14.1 dBic. [ABSTRACT FROM AUTHOR]

A miniaturized asymmetric coplanar strip fed with meander lines is developed for hexaband wireless applications. Multiband with compact size of the antenna is developed by using meander lines. The designed antenna is enhanced by an increased number of meander lines. The invented antenna is composed of three meander lines, it yields the antenna to excite 1.13, 2.35, 2.91, 3.46, 3.96, and 4.5 GHz, respectively. The prototype antenna is fed by ACS, which is printed on a 14 × $\times $ 24 × $\times $ 1.6 mm3 FR‐4 substrate and dielectric constant of Ɛr = 4.4. MATLAB tool is utilized in the ANN computation to amend the physical values of the antenna. The calibrated and simulated radiation attributes are identical with each other. The designed antenna provides distinguishing characteristics such as good reflection coefficient, impedance matching, and size miniaturization. It imparts empirical peak gains of 0.028 dBi at 1.14 GHz, 1.305 dBi at 2.35 GHz, 1.54 dBi at 2.86 GHz, 1.79 dBi at 3.43 GHz, 2.43 dBi at 3.96 GHz, and 2.58 dBi at 4.5 GHz, which is suitable for GSM/WLAN/WiMAX and C‐band wireless applications. [ABSTRACT FROM AUTHOR]

This paper presents a novel millimetre‐wave (mmWave) 2D wide‐angle scanning (WAS) phased array antenna (PAA) based on decoupling surface (DS). The proposed element is a coaxial feeding stacked patch antenna structure that consists of an L‐shape coaxial probe, substrate integrated waveguide cavity, slot layer, radiating patch, DS and defective ground structure. The simulated impedance bandwidth for the element is 14.85% (26.18–30.34 GHz). The simulated result of the 2 × 2 array shows that the designed antenna based on DS achieves an isolation of ≥19 dB within the bandwidth. To validate the scanning capabilities of the proposed antenna, an 8 × 8 PAA prototype is fabricated and measured. The measured scanning range of the prototype achieves a 2D WAS range of ±56° at 27 GHz. The proposed antenna shows great potential in application scenarios, such as automotive radar and satellite communication due to its compact design and ability to achieve WAS in two dimensions. [ABSTRACT FROM AUTHOR]

In this paper, a novel stacked wideband differentially feed antenna with dual polarizations is designed for base station. The circular parasitic patch deepens the resonance depth by slotting. Two linear dipoles are placed at ±45 - under the circular parasitic patch to reduce the overall size of the antenna. The antenna introduces a cross-shaped differential feed to achieve high port isolation. Finally, the designed antenna is fabricated and tested. The test results show that the differential reflection coefficient |Sdd11| is more than 15 dB. The antenna achieves a differential impedance bandwidth of 53.1% (1.63 GHz-2.8 GHz). The isolation is greater than 42 dB over the entire operating bandwidth. The antenna also has a stable gain of 8.2 ± 0.4 dBi and a half-power beamwidth of 65° ± 4°. [ABSTRACT FROM AUTHOR]

Here, a transition technique for converting signals from rectangular waveguide to coupled microstrip lines (CML) is presented, which provides a solution for differential antenna array feeding of automotive radar. The key to the proposed transition structure is to connect the coupling patches together with a short‐bridge structure, thus forming a quasi‐loop structure. Through the short bridge, the radiation efficiency of the antenna is greatly enhanced, and the mode conversion from TE10 of rectangle waveguide to differential mode of coupled microstrip line is realized effectively under the extremely compact size. Finally, the designed transition structure is manufactured and measured. The experimental results show that the back‐to‐back insertion loss is lower than 0.65 dB and the return loss is higher than 16.8 dB in the W‐band (75–110 GHz), which is the best performance and the simplest design among the relevant transition transitions reported so far. [ABSTRACT FROM AUTHOR]

This paper proposes and analyzes a 2 × 2 multi‐input multioutput antenna based on an open‐loop resonator structure and an inverted L structure. The top layer of the antenna uses symmetric inverted hook‐shaped and inverted L branches and is connected to the bottom layer of the dual‐feed port and the ground plane using the VIAs, respectively. The open‐loop resonator structure at the bottom of the antenna and the top layer of the branched circuit are resonated to provide wide‐bandwidth and dual‐frequency characteristics. The substrate uses FR4 with an area of 40 × 30 × 0.8 mm3. Although the two antenna feed ports are very close to each other, using via to connect the defective bottom ground structure and the top inverted L‐shaped branch, the isolation still achieves an excellent performance of 15 dB. The antenna has multiband application characteristics, and the bands include 2.29–5.51, 6.14–10.26, 2.29–5.33, 5.19–6.64, and 6.78–10.16 GHz. In pattern and MIMO transmission efficiency measurement, the peak radiation efficiency is 89%, the peak gain is 8.5 dBi, and the ECC is less than 0.034. In the transmission efficiency measurement mode using 64‐QAM, watching the error vector magnitude at 2.56 and 5.11 GHz, the demodulation effect is very good, and the respective throughput results are 100% and 79.2%. The broadband characteristics of the antenna have a variety of applications, and it is simulated at the specific absorption rate, which meets the standards set by the Federal Communications Commission and is very suitable for use in wearable devices. The antenna can be applied to the X‐band, n77, n79, Sub‐6 GHz, WiMax, DSRC, WiFi 6, WiFi 6E, WiFi 7, C‐V2X, and C‐band. [ABSTRACT FROM AUTHOR]

In this work, varoius dual-band WLAN MIMO antennas are designed and implemented. Measuremnet Results show that the working bands of these antennas are (2.40–2.48) GHz and (5.1–6.0) GHz. Metallic barrier are used to increase isolation among the ports of the WLAN MIMO antennas. For the two elements WLAN MIMO antenna with parrallel feed, isolation between ports of this antennas is higher than 18 dB. For the 2*2 (four) elements WLAN MIMO antenna with parrallel feed, isolation between ports of this antennas is higher than 19 dB. [ABSTRACT FROM AUTHOR]

ABSTRACT This paper starts with the proposal of an enhanced version of a planar rectangular slot antenna fed by the quasi‐TEM printed ridge gap waveguide (PRGW), attended with a numerical study of a miniaturization procedure showing the limitations of the conventional PRGW‐based antennas. Then innovative solution is introducing a new miniaturized pure TEM wide‐band slot antenna utilizing double PRGW (D‐PRGW) technology; the proposed approach is self‐packaged and shows high potential for enhancing antenna performance, particularly in terms of bandwidth, gain, and compactness. This technology is featured with low loss, high performance, and compact size; it consists of surrounding the ridge area with a double layer of electromagnetic band gap (EBG) lattice instead of one to eliminate the surface waves effectively and keep the signal completely confined inside the ridge area with strict minimum rows of EBG. Therefore, a broad impedance matching bandwidth (|S11| ≤ −10 dB) of 33.33% is obtained from 50 to 70 GHz, which covers the unlicensed NR parts (n262; amp; n263) of the V band. Furthermore, the antenna achieves a peak gain of approximately 16 at 65 GHz while the overall efficiency remains above 90% across the entire operating frequency band. The high performance along with the compact size of this novel design makes it a good candidate for 5G wireless communications applications centered around 60 GHz. [ABSTRACT FROM AUTHOR]

This paper presents a novel additively manufactured wideband dual circularly polarized (CP) open‐ended waveguide (OEW) antenna, which adopts a pair of wedge‐shaped outer ridges acting as a circular polarizer. Study found that compared to the con‐ ventional designs that employ internal polarization converting structures, such outer ridges are capable of achieving wider axial ratio bandwidth (ARBW) and better reflection coefficients. On each ridge, two rectangular slots are designed to suppress the higher order mode caused by the increased waveguide size, and further expanding the ARBW. The proposed antenna is fed by two differential ports. By switching the feeding ports, the CP states can be altered to either right‐handed CP (RHCP) or left‐handed CP (LHCP). In terms of configuration, the proposed antenna has a simple one‐piece structure and is fabricated by using dielec‐ tric 3‐D printing technology. To form the waveguide walls, its partial surfaces are coated by copper films through electroplat‐ ing. The proposed antenna features easy fabrication and light weight. Experimental results show that the proposed antenna has an impedance bandwidth of larger than 47.6% (8–13 GHz) with reflection coefficients lower than −15 dB, while the 3‐dB ARBW is 37.7% from 8.4 to 12.3 GHz. [ABSTRACT FROM AUTHOR]

A ground station antenna system features a conical horn attached to a microstrip antenna as an alternate receiving feed antenna. The proposed microstrip antenna has circular polarization and operates in the X-band. The far-field parameters of the antenna are measured after developing and simulating the combination of a conical horn and a microstrip antenna. The modeling results for a microstrip antenna with a conical horn offer a working bandwidth of 930 MHz, spanning frequencies 7.44 GHz to 8.37 GHz. The axial ratio measurements for a microstrip antenna joined with a conical horn produce a working bandwidth of 150 MHz, covering frequencies ranging from 7.72 GHz to 7.87 GHz. The conical horn is attached to a microstrip antenna and has a gain of 15.1 dB. The proposed antenna is designed to meet ground station antenna requirements by pairing it with a parabolic reflector with a diameter of 3.7 meters. The primary focus antenna of the proposed design was chosen. The feed antenna and parabolic reflector should be positioned at a focus point distance of 1110 mm for a total gain of 38.9 dB at 7.8 GHz frequency. The proposed antenna can be applied on X-band remote sensing ground stations as a receiving antenna. [ABSTRACT FROM AUTHOR]

The Spaceborne Global Lightning Location Network (SGLLN) serves the purpose of identifying transient lightning events occurring beneath the ionosphere, playing a significant role in detecting and warning of disaster weather events. To ensure the effective functioning of the wideband electromagnetic pulse detector, which is a crucial component of the SGLLN, it must be tested and verified with specific signals. However, the inherent randomness and unpredictability of lightning occurrences pose challenges to this requirement. Consequently, a high-power electromagnetic pulse radiation system with a 20 m aperture reflector is designed. This system is capable of emitting nanosecond electromagnetic pulse signals under pre-set spatial and temporal conditions, providing a controlled environment for assessing the detection capabilities of SGLLN. In the design phase, an exponentially TEM feed antenna has been designed firstly based on the principle of high-gain radiation. The feed antenna adopts a pulser-integrated design to mitigate insulation risks, and it is equipped with an asymmetric protective loading to reduce reflected energy by 85.7%. Moreover, an innovative assessment method for gain loss, based on the principle of Love's equivalence, is proposed to quantify the impact of feed antenna on the radiation field. During the experimental phase, a specialized E-field sensor is used in the far-field experiment at a distance of 400 m. The measurements indicate that at this distance, the signal has a peak field strength of 2.2 kV/m, a rise time of 1.9 ns, and a pulse half-width of 2.5 ns. Additionally, the beamwidth in the time domain is less than 10°. At an altitude of 500 km, the spaceborne detector records a signal with a peak field strength of approximately 10 mV/m. Particularly, this signal transformed into a nonlinear frequency-modulated signal in the microsecond range across its frequency spectrum, which is consistent with the law of radio wave propagation in the ionosphere. This study offers a stable and robust radiation source for verifying spaceborne detectors and establishes an empirical foundation for investigating the impact of the ionosphere on signal propagation characteristics. [ABSTRACT FROM AUTHOR]

Dielectric resonator antennas have been demonstrated to be an efficient radiator, especially with the possibility of fabricating it at low cost based on 3-D printing technologies. However, they have two main limitations which are: their relatively small gain (about 5dBi) and narrow bandwidth. To enhance the gain of DRA, higher-order mode excitation can be utilized; however, typically this has a limit of a few dB increments besides its negative effects on the bandwidth. This study employs a cavity-backed slot to provide an appropriate feeding method for a cylindrical dielectric resonator antenna (CDRA). This design effectively facilitates the excitation of higher-order modes, resulting in a significant gain of up to 15 dBi, which is essential for many wireless systems that are unable to support larger aperture sizes through the standard use of arrays. Additionally, two modes are excited to keep a relatively broadband of about 15 %. The proposed design consists of a cylindrical dielectric placed on top of a cavity-backed slot that is excited by a coaxial probe soldered to the top patch of the cavity. With this feeding, a good matching is achieved for different dielectric resonator heights, hence, the gain can be adjusted easily without the need of reoptimizing the antenna or the feed structures. The design process is explained in addition to performing a sensitivity analysis of fabrication tolerances which confirms that the 3-D printer provides enough accuracy with a negligible effect on the antenna's performance. Then a prototype with a medium length is fabricated and measured to provide high realized gain and impedance bandwidth of 11 dBi and 14.5 %, respectively. The measured data demonstrate the good performance of the antenna with great matching compared to the simulated ones. Furthermore, the antenna presents a good performance in terms of sidelobes and polarization. This proposed design outperforms other DRA designs based on higher-order modes. [ABSTRACT FROM AUTHOR]

We analyze square antennas with one and quasi-two sources to reveal the relationship between loop and plate antennas. First, using the moment method, one-source antennas with corner truncation are investigated versus antenna height above the ground plane. As the height increases, the CP wave bandwidth of the plate antenna increases 17% for a 3 dB axial ratio criterion, whereas the loop antenna's bandwidth remains less than 3%. Next, we study quasi-two-source antennas without corner truncation versus antenna height. The plate antenna's bandwidth is found to reach 30%, which is wider than that of a loop antenna by a factor of two. Last, the plate antenna with quasi-two sources is applied in an array antenna, whose properties are compared to those of the corresponding loop antenna array. We present experimental results to verify the simulated results. [ABSTRACT FROM AUTHOR]

This paper proposes an antenna based on a rectangular waveguide to generate dual higher-order orbital angular momentum (OAM) beams. The OAM beams with modes l = −6 and l = −7 are produced by radiating the higher order TEmn transmitted in the rectangular waveguide through a slot. The measurement results indicate that the impedance bandwidth of less than −10 dB is approximately 37.8% in the range of 15–22 GHz, and the mode purity of the antenna is above 55%. The proposed antenna feed structure is simple and does not require a complex phase-shifting network to generate multi-mode and higher-order OAM beams. Such an OAMbased antenna with dual higher-order OAM beams can be utilized in MIMO-OAM communication systems, radar imaging systems, and rotational speed measurement systems. [ABSTRACT FROM AUTHOR]

This paper proposes a novel feed array antenna to achieve a uniform electric field distribution in the near-field region for feeding a large-aperture antenna. The feed antenna has a 4 × 4 rectangular array configuration to obtain uniform near-field distribution on a virtual target surface. Each element of the array consists of a Vivaldi radiator and parasitic rings, and these two components have different radiating modes. In particular, the near-field pattern of the parasitic rings can be varied by adjusting their radii. Thus, the required near-field distribution on the virtual target surface can be achieved by optimizing the radii of the parasitic rings. To further enhance the uniformity of the electric field, the input phase of each Vivaldi radiator is adjusted by applying different transmission line lengths to the Vivaldi radiators depending on their positions in the array. To verify the feasibility of the proposed antenna, the electric field distributions are measured in an electromagnetic anechoic chamber. The results demonstrate that the proposed feed array antenna can achieve uniform near-field distribution with an average of 1.7 dB and a deviation of 6.8 dB on the virtual target surface placed within half a wavelength from the antenna aperture. [ABSTRACT FROM AUTHOR]

Abstract This paper presents a novel millimetre‐wave (mmWave) 2D wide‐angle scanning (WAS) phased array antenna (PAA) based on decoupling surface (DS). The proposed element is a coaxial feeding stacked patch antenna structure that consists of an L‐shape coaxial probe, substrate integrated waveguide cavity, slot layer, radiating patch, DS and defective ground structure. The simulated impedance bandwidth for the element is 14.85% (26.18–30.34 GHz). The simulated result of the 2 × 2 array shows that the designed antenna based on DS achieves an isolation of ≥19 dB within the bandwidth. To validate the scanning capabilities of the proposed antenna, an 8 × 8 PAA prototype is fabricated and measured. The measured scanning range of the prototype achieves a 2D WAS range of ±56° at 27 GHz. The proposed antenna shows great potential in application scenarios, such as automotive radar and satellite communication due to its compact design and ability to achieve WAS in two dimensions.

The proposed Minkowski fractal antenna design achieves wideband and continuous frequency tuning in a multiple-input and multiple-output (MIMO) antenna system. By manipulating the fractal geometry of the unit antenna element, the resonance frequency of the antenna can be adjusted simply by changing its electrical length. The Minkowski fractal operator generates an increasing current path, resulting in a leftward frequency shift as the antenna side length increases with each iteration. In the first iteration, the proposed fractal antenna demonstrated a 97.9% continuous frequency shift from 0.204 to 0.404 THz with maximum return loss values of −31.23 and −21.6 dB, respectively. In the second iteration, a 38.6% continuous resonance frequency shift from 0.413 to 0.578 THz was achieved with return loss values of −18.22 and −40.47 dB, respectively. The maximum tunable bandwidths of the first and second iterations were approximately 0.2 and 0.16 THz, respectively. The proposed correlation between the dimensions of a single antenna and its resonance frequency provides the foundation for designing and implementing MIMO antenna systems in high-speed wireless devices, cognitive radio, and other multiband MIMO applications. A 2 × 2 MIMO antenna system has been designed from the results of the proposed single antenna to achieve multiband operation or frequency tuning through selective switching of the antenna feed. [ABSTRACT FROM AUTHOR]

Abstract Mutual coupling among multiple antennas has been a problem needed to be tackled in multiple‐input‐multiple‐output (MIMO) systems. A decoupling method based on short decoupling feeding lines (DFLs) for MIMO patch antennas is proposed. The decoupling method utilises the feeding transmission line to create a new coupling path between the closely placed patch antennas. By adjusting the intensity and phase of the introduced new coupling, the original coupling can be cancelled out. The proposed method can realise both E‐ and H‐plane decoupling. A 1 × 2 H‐plane MIMO patch antenna array is first presented to explain the decoupling mechanism. Then, two practical examples of 2 × 2 and 4 × 4 MIMO patch antenna arrays are designed, fabricated and measured. The results indicate that the port isolation can be apparently improved from 15 to 38 dB for H‐plane coupling and from 19 to 35 dB for E‐plane coupling at the centre frequency of 3.5 GHz. Moreover, the proposed method is promising to be applied in arrays with other antenna type by adjusting the position and size of short DFLs.

This paper presents a complementary split-ring resonator (CSRR) loaded coplanar waveguide (CPW) fed with a circular shape, miniaturized diamond slot planar monopole antenna. The proposed antenna for healthcare monitoring biomedical applications uses the industrial medical and scientific band. The antenna design and development to implant the human phantom are proposed. The primary goal of this work is to continuously monitor the patient's ability to detect abnormal conditions as soon as possible as a result of improvements in quality of life. In this case, an antenna design methodology must prioritize features such as miniaturization, increased gain and bandwidth, and biocompatibility. Simulated and measured antenna characteristics for biomedical applications are performed at ISM Band frequency. [ABSTRACT FROM AUTHOR]

Summary In this article, a compact quad element coplanar waveguide (CPW) fed ultra‐wideband (UWB) multiple input multiple output (MIMO) antenna for future generation wireless communication system using a machine learning (ML) optimization approach is presented. The proposed antenna is used for 5G new radio (n46/n77/n47/n78/n48/n79), Wi‐Fi 5, Wi‐Fi 6, and dedicated short range communications (DSRC) services, vehicle to infrastructure (V2I), vehicle to vehicle (V2V), and vehicle to network (V2N) in the entire operating frequency band. It is operating from 3.2 to 11.85 GHz. The bandwidth is 8.65 GHz, and the percentage of impedance bandwidth is 115%. The comparative analysis between dual and quad elements are presented. It is optimized through the various ML model K‐nearest neighbor (KNN), extreme gradient boosting (XGB), artificial neural network (ANN), and random forest (RF). The KNN ML model achieved a higher accuracy of 93%, and it accurately predicted the S parameters of the suggested UWB antenna. The MIMO parameters are calculated and found within the acceptable limits. There is a strong correlation between the simulated and measured results. Hence, the suggested antenna is a suitable candidate for future wireless communication systems. [ABSTRACT FROM AUTHOR]

New configurations of 2-D phased arrays are proposed in this paper for reducing the number of phase shifters. This design methodology is based on the use of a novel coherently radiating periodic structures (CORPSs) block for 2-D phased arrays. Two new antenna systems for 2-D phased arrays are studied and analyzed utilizing the CORPSs blocks of four inputs and nine outputs. These CORPSs feeding blocks are applied in a smart way to feed the planar antenna arrays by generating the required phase plane and reducing the number of control ports. Interesting results are provided based on the experimental measurements and full-wave simulations. These results illustrate a great reduction of the active devices (phase shifters), providing a good design compromise in terms of the scanning range and side lobe level performance. Furthermore, the provided results illustrate a maximum reduction capability in the number of phase shifters of 81%, considering a scanning range of ±30° in azimuth and ±30° in elevation. A raised cosine distribution is applied to reach side lobe levels of −19 dB for ±18° and −17 dB for ±30° in elevation. These benefits could be of interest to designers of phased antenna systems. [ABSTRACT FROM AUTHOR]

Summary This paper presents the design and performance evaluation of a single‐layer, high‐gain, millimeter‐wave (mm‐wave), corporate–series‐fed, 16‐element circular patch array antenna tailored for the 28 GHz frequency band, pertinent to fifth‐generation (5G) wireless communication systems. The proposed antenna configuration employs a dual‐port feeding technique, where consecutive junction patches are interconnected with two separate feed networks. By simultaneously exciting the two ports with identical amplitude but opposite phases, the antenna achieves high gain directed towards the broadside. The proposed structure is fabricated on a grounded substrate, enabling accurate performance measurement of the prototype. Close agreement between simulated and measured results validates the precision of the designed structure. The measured performance of the proposed antenna configuration demonstrates an impedance bandwidth of 3.79% within the desired frequency band of 27.6‐28.7 GHz for S11 ≤ −10 dB. Experimental measurements demonstrated that the mutual coupling between the two distinct ports is <−30 dB, with a diversity gain exceeding 9.99 dB. Simulated radiation efficiency exceeds 90% at the 28 GHz center frequency, while the measured peak gain approaches 17.7 dBi. Measured stable radiation plots specify that the proposed array exhibits broadside patterns with half‐power beamwidths (HPBWs) of 30.4° and 11.3°, sidelobe levels (SLLs) below −25 and −10 dB, and cross‐polarization levels <−25 dB in both the E and H planes, respectively. The superior performance characteristics of the proposed array antenna make it well‐suited for 28 GHz mm‐wave 5G applications, facilitating efficient and reliable long‐range communication in the mm‐wave spectrum. [ABSTRACT FROM AUTHOR]

Summary: A design problem of multiband multi‐input, multi‐output (MIMO) antenna arrays for maximal side lobe level lessening with constraint of a fixed beam width is dealt with. Multiband MIMO antenna is the most promising solution in a communication system, due to its maximal speed, higher data rate, and short‐range communication. Conversely, MIMO faces several complications including designing a proper antenna for a specific bandwidth and lesser antenna efficacy. In this manuscript, a high‐resolution CP multiband MIMO (HS‐CPMB‐MIMO) antenna design for wireless communication is proposed. MIMO antenna plays a vital part in the present wireless technology at MSA. A multiband microstrip line‐fed two‐port hybrid CPMIMO antenna is intended and fabricated. The proposed microstrip feed antenna contains a tapering structure, and the inverted L‐shaped slots in the radiating element are opened on both sides to present notches in sub‐6‐GHz frequencies. The inverted L‐shaped slots is positioned in the middle of asymmetric Z‐shaped radiating elements for enhancing the isolation among the two ports. The invention of a multiband MIMO antenna with four CP bands has an efficient ECC value because of a large L‐shaped slot in the ground as well as a protruding Z‐shape ground stub embedded with circular rings to have highly isolated cells. Finally, the proposed HS‐CPMB‐MIMO antenna design is implemented by utilizing simulation software CST Microwave Studio, and it is evaluated with the performance metrics. The simulation outcomes of the proposed HS‐CPMB‐MIMO antenna provide 36.34%, 57.36%, and 25.33% higher BW, 24.13%, 15.96%, and 21.22% higher gain compared with existing methods. [ABSTRACT FROM AUTHOR]

In this paper, a design for a conformal inhomogeneous lens antenna is presented that available high gain and directivity with a low profile and conformal shape. The design is based on the critical angle theorem and mapping of parabolic coordinates, resulting in a lens that offers a good match to the feed antenna and the surrounding environment. This lens is suitable for use in millimeter, THz, and optical frequencies. To confirm the results in the designed frequency band, a parametric model is provided based on the design frequency, and full wave simulations using Comsol multi-physics software are used. [ABSTRACT FROM AUTHOR]

This paper presents an innovative and condensed blueprint for an ultra‐wideband (UWB) printed monopole antenna, aiming to augment bandwidth and achieve dual band‐stop capabilities, all while accounting for the impact of the human body model on stop bands. The proposed design showcases a square radiating patch situated on the top layer of the substrate, complemented by a ground plane etched on the underside, integrating two sets of adapted U‐shaped slots. Such a configuration delivers a broad operational fractional bandwidth that surpasses 132%. Within our design, a modified C‐shaped slot in the radiation patch creates the first band‐stop property, while a pair of modified F‐shaped slots etched in the radiation patch generates the second stop‐band property. Measuring 12 mm × 18 mm × 0.8 mm, the antenna offers a compact form factor, broad bandwidth, cost‐effectiveness, omnidirectional radiation patterns within the H‐plane and acceptable behavior for using in In‐body microwave applications. [ABSTRACT FROM AUTHOR]

In this paper, a novel method for detecting breast cancer utilizing an ultra-wideband (UWB) microstrip patch antenna operating in the UWB frequency range is presented. The promise of non-invasive, radiation-free breast cancer screening is provided by UWB technology. We give a brief overview of the difficulties in detecting breast cancer as well as the benefits of UWB technology in medical applications in this study. This study presents a compact printed microstrip patch antenna used for the bio-medical application at industrial, scientific, and medical (ISM) and UWB frequencies. The proposed antenna consists of a hexagonal-shaped microstrip patch antenna with a slotted ground antenna used for high bandwidth for a wider range of applications. The compact biomedical antenna is printed on Roger 5880 substrate with an overall dimension of 25*25 mm. Due to the high demand for results accuracy, Roger 5880 substrate material is used because it has good dielectric characteristics and loss factors that are appropriate for medical and radio frequency (RF) applications. A 50-ohm impedance line is used to feed the antenna. The proposed antenna has a higher bandwidth of almost 12.5 GHz at such a low frequency, starting from 3.53 to 16 GHz. The antenna has an acceptable gain of 3.38 Db, which is enough for the required application. The UWB microstrip patch antenna has the potential to improve breast cancer detection accuracy and reliability, which would aid in early diagnosis and better cancer patient treatment. This work represents a major advancement in the development of non-invasive, low-cost breast imaging methods for early cancer diagnosis. [ABSTRACT FROM AUTHOR]

Holographic multiple-input multiple-output (HMIMO) systems constitute a promising technology in support of next-generation wireless communications, thus paving the way for a smart programmable radio environment. However, despite their significant potentials, further fundamental issues remain to be addressed, such as the acquisition of accurate channel information. Indeed, the conventional angular-domain channel representation is no longer adequate for characterizing the sparsity inherent in HMIMO channels. [ABSTRACT FROM AUTHOR]

A new type of compact line-fed MIMO antenna for 5G wireless communication is presented in this paper. A rectangular microstrip patch antenna with an inset feed is designed for the 28 GHz and 38 GHz bands. T-shaped patch contains inverted I-shaped slots, providing a dual-band response at 28 GHz and 38 GHz. By integrating two T-shaped patches, the MIMO (Multiple Input Multiple Output) antenna significantly improves signal diversity and data throughput, making it highly suitable for modern wireless applications such as 5G networks. Slot-formed defected ground structures (DGSs) are inserted into a partial rectangular ground plane. To fit into handset devices for the upcoming 5G mobile revolution, the antennas are modestly configured on a substrate measuring 14×28 mm², occupying minimal area and reducing mutual coupling. The ECC, MEG, TARC, and radiation efficiency values obtained from the antenna systems are suitable for 5G mobile applications, with excellent reflection coefficient characteristics. [ABSTRACT FROM AUTHOR]

This research proposal includes the design of a unique coplanar waveguide (CPW) fed ultra-wideband (UWB) antenna prototype with dual notch band characteristics. The microstrip line fed antenna features a configuration of geometric slots, including a rectangle, a semi-circle slots, and a pentagonal stub, along with a microstrip feedline. The antenna measures 35.4 mm × 28.82 mm. Two notches are introduced at 5 to 5.8 GHz (14.8% bandwidth) and 7.2 to 7.8 GHz (8% bandwidth) by incorporating split ring resonators (SRRs) on the bottom surface. Aside from the dual stopbands for the WLAN band (5 to 5.8 GHz) and SHF satellite communication band (7.2 to 7.8 GHz), the designed antenna operates over an impedance bandwidth from 3 GHz to 11.2 GHz with voltage standing wave ratio (VSWR) below 2. The proposed antennas have been developed, prototyped, and successfully verified. Simulation data and measurement results are thoroughly examined and analyzed. To confirm the applicability of the antenna in pulsed communication systems, the correlation among the input signal of the transmission antenna with the output signal of the reception antenna in the time domain is estimated. This confirms that the antenna prototype is well suited for wireless communication applications in military radar systems, medical imaging, consumer electronics, and more. [ABSTRACT FROM AUTHOR]

In this paper, a new simple practical technique for controlling the element excitation amplitudes of the array feeding network is presented. To implement this novel idea, an array with four rectangular microstrip patches operated at 3.25 GHz is fabricated. Genetic algorithm was used to determine the optimum excitation amplitudes of these four patches such that its array pattern has a minimum sidelobe level. An Arduino microcontroller was used to apply the optimized excitation amplitudes via programmable digital attenuators that connected to each adjustable element. Measured results show that the peak sidelobe level in the designed array pattern was reduced from -13.2 dB to more than -26 dB which is practically sufficient to eliminate the effect of any interfering signals. More important, the main beam and the directivity are not much affected by the sidelobe reduction. Thus, the technique is practically effective and it can be easily used in designing the adaptive beamforming antenna arrays for 5G and beyond wireless applications. [ABSTRACT FROM AUTHOR]

This study investigates the potential for significant enhancements in the gain and return loss of a microstrip antenna through the meticulous design of slits and a triangular slot in the radiation patch, coupled with precise dimensioning of these elements and careful selection of the feeding point. To this end, a microstrip patch antenna with multiple slits and a triangular slot was designed and simulated on an FR-4 with a dielectric constant (ε) of 4.4. In the initial configuration, the antenna exhibited a gain of 2.3 dB at 5.79 GHz for the maximum Eɵ at θ = 6º, with an S11 value of -16.5 dB. The antenna biasing and feed position were carefully optimized to achieve the desired performance improvements, in addition to meticulous design considerations for gain and return loss enhancements. The optimized antenna demonstrated a gain of 6.2 dB at 6 GHz for Eɵmax at θ = 0º, along with an S11 value of -24.3 dB. The final optimized configuration was fabricated and subjected to rigorous laboratory measurements for validation. The proposed antenna demonstrated an S11 value of -18.6 dB, along with a corresponding gain of 5.4 dB for Eɵmax at θ = 0º at 6 GHz. Furthermore, it was observed that the bandwidth increased by 330 MHz compared to its initial state. Finally, a comparative table is presented comparing the proposed antenna with other similar antennas found in the literature. Based on this table, it is evident that the gain enhancement can be achieved in a remarkable manner without altering the overall dimensions of the antenna and without the need for an expensive substrate with high permittivity. [ABSTRACT FROM AUTHOR]

In this study, we propose a method for designing a feeding network for all port-matched and high gain dipole subarray antennas excited by uniform current mode (UCM) by considering the mutual coupling effect. By analyzing the array impedance matrix, we first calculated the active input impedance and the required excitation power. Following this, we transformed and combined the complex impedances using the proposed power divider, thus preserving the required excitation power. The design process and results of this study are demonstrated stepwise through circuit simulation. Subsequently, we fabricated and evaluated the proposed subarrays. The impedance matching performance of the UCM was found to be better than that of the conventional subarray, with their array gains being 11.5 dBi and 9.8 dBi, respectively. [ABSTRACT FROM AUTHOR]

This paper proposes a printed ridge gap waveguide (PRGW)-based 2 × 2 millimeter-wave antenna array with broad bandwidth and compact aperture. A dual-resonance element consisting of a quarter circular and a quarter annular patch is initially designed. Subsequently, to reduce the cross polarization (XP) radiation and enhance the gain of the proposed antenna, a four-element array with symmetric arrangement is developed, leading to a decline in the normalized XP levels from -4.5 to -18.9 dB and from -4.4 to -18.7 dB in the xoz and yoz planes, respectively. In addition, a pair of parasitic shorted half-circular patches is loaded to improve the antenna gain in the highfrequency range. Finally, a PRGW feeding network is designed and applied to provide differential feeding for the planar array. To validate the reflection and radiation performance, an array prototype is fabricated, and experimental verification is conducted. Measurement results show that a -10-dB impedance bandwidth of 14.3% (26.0-30.0 GHz) is realized for the prototype, and an average realized gain of 9.8 dBi with low XP radiation is achieved by the proposed array. [ABSTRACT FROM AUTHOR]

A dual-band (K-/Ka-band) antenna array is presented. An ultra-wideband antenna element in the shape of a double-ridged waveguide is used as a radiation slot, and a novel dual-periodic ridge gap waveguide (RGW) with an interdigital-pin bed of nails (serving as a filter) is used to realize dual-band operation. By periodically arranging the pins of two different heights in two dimensions, the proposed RGW with interdigital-pin bed of nails is able to realize and flexibly adjust two passbands. The widely used GW-based back cavity boosts the realized gain and simplifies the feed network design. A 4 × 4 prototype array was designed, fabricated, and measured. The results show that the array has two operating bands at 24.5–26.4 GHz and 30.3–31.5 GHz, and the realized gain can reach 19.2 dBi and 20.4 dBi, respectively. Meanwhile, there is a very significant gain attenuation at stopband. [ABSTRACT FROM AUTHOR]

We demonstrate the design of a highly directive circularly polarized planar reflectarray in this paper, with efficient polarization conversion from the linearly polarized excitation to the circularly polarized radiations based on a novel Jerusalem like cross loaded C-shaped open loop and circular patch anisotropic metasurface. The full-wave simulation results clearly show that circularly polarized plane waves could be generated by the proposed anisotropic metasurface after the linearly polarized incident waves emitted from the horn feed antenna at 15 GHz. Finally, we fabricate the proposed reflectarray antenna, and demonstrate the perfect generation of triple circularly polarized beams with the axial ratio of these beams all less than 2 dB, and an average gain of 22.4 dBic. [ABSTRACT FROM AUTHOR]

This article describes a new design for the sum-channel, circularly-polarized, radiating patch element of a multimode patch-monopole monopulse feed. Such feeds are suitable for the prime-focus illumination of a deep symmetric reflector. A relatively simple and compact feed design allows for a compact single-mirror antenna with monopulse tracking. The feed is about a wavelength in diameter, also making it suitable for illuminating smaller antennas, for example, in LEO-satellite ground (client) stations. The design applies a slotted circular patch as a circularly-polarized sum-channel element. The design variables are optimized mainly for the sum-channel aperture illumination efficiency in an S-band satellite ground station. After a few cut-and-try iterations, the final feed prototype was produced and measured. In addition to an additional degree of freedom in the geometry and potentially easier fabrication, the new sum-channel radiating-element shape allows for a slightly better monopulse channel isolation, and a higher radiation-pattern symmetry compared to the previous design. [ABSTRACT FROM AUTHOR]

In this paper, a multiband microstrip antenna of compact size (0.2 × 0.25 ) is designed by loading multiple notches in the patch of antenna. The patch of antenna consist two L-shaped and two rectangular shaped notches. The modified patch of antenna provides triple resonating bands from 1.58 to 1.71 GHz, 1.89 to 2.06 GHz and 2.81 to 2.93 GHz under the − 10 dB scale resonating at frequency 1.63 GHz, 2 GHz and 2.87 GHz respectively. The bandwidth of triple band antenna is obtained 7.9% (130 MHz), 8.61% (170 MHz) and 4.18% (120 MHz) with − 16.6 dB, − 26.99 dB and − 31.88 dB reflection coefficient at resonating frequency. The lower and middle resonances are due to L-shape notches while higher resonance is due to rectangular shape notches. The presented antenna is fed by microstrip line feed of 50 Ω and the simulation is performed by IE3D software. It shows 2.6−3.1 dB, 2.9−3.5 dB and 4.2−5 dB simulated gain and 85−93%, 87−95% and 88−96% antenna efficiency in three resonating bands. The three resonating bands of proposed antenna can be used for the application of different wireless communications in L and S-bands. The proposed work is also compared with the previous published articles to find out the improvement. [ABSTRACT FROM AUTHOR]

Summary This research proposes a novel low‐cost aperture coupled elliptic patch nanoantenna which works best when it has a stable radiation pattern and good gain. On the upper portion of the substratum, a cross‐shaped hole was additionally engraved from a metallic strip with a silver composition. Elliptical‐shaped silicon material is employed as a patch in this antenna design which is made on a substrate made of inexpensive glass epoxy. The silver substance makes up the nanometallic strip line at the substrate's base. A cross‐shaped hole has also been etched from a metallic strip with a silver composition on the upper section of the substrate. As the foam substrate to be used in between the feed and antenna substrates, Rohacell was adopted. A proposed simple cross‐shaped aperture enhanced the bandwidth of the planned antenna without degrading its radiation performance and is loaded on a proximity‐linked elliptical microstrip antenna. To achieve the highest coupling, the lowest back radiation, the least amount of spurious radiation, and good efficiency, the patch and feed line are positioned in the middle, at a right angle over the slot. The proposed antenna was simulated in HFSS, and optimum results were observed from the output. The results were evaluated based on radiation pattern, return loss, smith chart, radiation efficiency, and 3D polar plot for 300, 500, and 800 THz frequencies. Also, the impedance bandwidth, gain, and a number of bands were compared with other conventional methods and our proposed method proved to outperform the existing method in all aspects. [ABSTRACT FROM AUTHOR]

In this paper, a MIMO antenna with broadband circular polarization is designed in a single‐layer substrate for the next‐generation Wi‐Fi 7 applications. The top of the substrate is designed with a periodic array of 5 × 5 circle patches and orthogonally placed four L‐shaped aperture CPW feeds on the bottom face of the substrate are used to feed the patches. The stubs are arranged across the apertures to achieve a broad bandwidth. The array of patches is used to achieve high gain over resonant frequency range and L‐shaped apertures are used to achieve circular polarization. The designed antenna with the above specifications has gained an impedance bandwidth of 20.4% (5.37–6.59 GHz), a 3 dB axial ratio bandwidth over the entire resonant frequency range of 25.61% (5.14–6.65 GHz) and a peak gain of 8.5dBi. [ABSTRACT FROM AUTHOR]

Over the past years, remote sensing, radar, and imaging applications have all made use of ultra-wideband (UWB) technology. This study undertakes an extensive analysis of tree-shaped monopole antennas tailored for UWB systems. The intended antenna has an incomplete ground plane and a circular radiating patch. To increase bandwidth, two ears have been added to the circular structure. Possessing a dielectric constant of 4.3. The antenna substrate consists of FR-4 material with a dielectric constant of 4.3. To achieve optimal impedance matching for UWB systems, the antenna is fed via a coplanar waveguide (CPW). Design antenna is a simple structure, small size, easy design, and simple integration with the substrate with dimensions of 54 mm ×36 mm ×1.6 mm. All simulation results presented in this article were generated using computer simulation technology (CST) software. He monopole antenna exhibits an impressive impedance bandwidth of 9.6 GHz (146.68%), spanning from 1.99 GHz to 11.56 GHz. Furthermore, the simulated UWB circular monopole antenna exhibits omnidirectional radiation characteristics, boasting a peak gain of 8 dB, and a directivity of 8.2 dBi at the frequency of 5 GHz, and a remarkable radiation efficiency of 97%. With these attributes, the suggested monopole UWB antenna shows significant potential for ground penetrating radar (GPR) applications. [ABSTRACT FROM AUTHOR]

Mutual coupling among multiple antennas has been a problem needed to be tackled in multiple‐input‐multiple‐output (MIMO) systems. A decoupling method based on short decoupling feeding lines (DFLs) for MIMO patch antennas is proposed. The decoupling method utilises the feeding transmission line to create a new coupling path between the closely placed patch antennas. By adjusting the intensity and phase of the introduced new coupling, the original coupling can be cancelled out. The proposed method can realise both E‐ and H‐plane decoupling. A 1 × 2 H‐plane MIMO patch antenna array is first presented to explain the decoupling mechanism. Then, two practical examples of 2 × 2 and 4 × 4 MIMO patch antenna arrays are designed, fabricated and measured. The results indicate that the port isolation can be apparently improved from 15 to 38 dB for H‐plane coupling and from 19 to 35 dB for E‐plane coupling at the centre frequency of 3.5 GHz. Moreover, the proposed method is promising to be applied in arrays with other antenna type by adjusting the position and size of short DFLs. [ABSTRACT FROM AUTHOR]

A single‐layered W band circularly polarised (CP) antenna array fed by a sequential feeding network using compact gap waveguides (GWs) with reduced pins is presented. The radiating element consists of a pair of cross slots and an open‐ended rectangular cavity integrated into the top metal plate of the GW. A sequential rotation network (SRN) consisting of hybrid groove gap waveguide (GGW) and ridge gap waveguide (RGW) structure is presented. Due to the fact that conventional GWs with multiple rows of pins occupy large lateral size, thus making them difficult to realise a single‐layered CP array fed by SRN. Compared with conventional GW with multiple rows of pins, compact GGW with a single row of pins is deployed here to make the presented SRN more compact, thus combining SRN and multiple CP radiators in the same layer. Particularly, a comprehensive investigation on the choice of the GGW groove depth is carried out. The groove depth is designed carefully such that the electric‐field energy is more confined along the GGW line, and less rows of pins are required. For proof‐of‐concept demonstration, the proposed array has been fabricated and measured, exhibiting an overlapped bandwidth of 10.64% (89–99 GHz) and a peak gain of 19.48 dBi at 94 GHz. It presents a promising candidate for W band wireless applications. [ABSTRACT FROM AUTHOR]