Search

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]

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]

In this paper, a broadband circularly polarized (CP) antenna array with stable radiation pattern is proposed for satellite communication applications. The antenna array consists of a 2 $ \times $ × 2 planar antenna array and a feeding network. Based on the magneto-electric (ME) dipole antenna structure, the electric dipoles are modified, and a pair of shorting pins are introduced to adjust the surface current. The bandwidth problems of circular polarization are effectively improved. Then the 2 $ \times $ × 2 broadband CP antenna array is designed and fabricated. The measured results show that the −10 dB impedance bandwidth of 56.3% from 11.1 to 19.79 GHz, and the 3 dB axial ratio (AR) bandwidth of 32.1% from 11.72 to 16.20 GHz. The 3 dB gain bandwidth of 44.2% from 11.10 to 17.40 GHz, and the peak gain is 11.07 dBi. Owing to the above excellent performance, the proposed antenna array can be a candidate for satellite communications. [ABSTRACT FROM AUTHOR]

A circularly polarized compact two-port MIMO antenna is presented along with asymmetrical CPW feed and a novel decoupling structure. The asymmetric CPW feed of the antenna is improving the impedance matching significantly and shifting the operating band towards the lower frequency. The novel inverted Z-shaped decoupling is used to enhance the isolation which mitigates the surface wave effectively between two antennas. The triangular-shaped inductive stubs are unified in the inverted Z-shaped decoupling structure which is used to perturb the surface wave movement and to influence the circular polarization (CP) behaviour in the two-port antenna. MIMO antenna obtains the 10 dB impedance bandwidth (IBW) from 6.38 GHz to 6.84 GHz along with minimum port isolation of 30 dB. The 3-dB axial ratio (AR) is obtained from 6.59 to 6.84 GHz frequency which is 52.1% of the total 10 dB IBW of the antenna. The proposed work can be prominent for super-extended C-band of satellite communication and Wi-Fi 6E U-NII6 and U-NII7 communication. [ABSTRACT FROM AUTHOR]

Presented in this paper is a simple, small-sized, and hook-shaped monopole antenna fed by an Asymmetric Coplanar Strip (ACS) for different dual-band operations. The antenna operates at 3.5 and 5.2 GHz; hence, serving WiMAX and WLAN applications. Dual resonances were attained by integrating a quarter-wavelength strip with a C-shaped half-wavelength loop strip. The proposed antenna footprint is 20 × 7.9 mm2. Based on the achieved outcomes and the antenna compactness, it can be highly nominated for use in 3.5/5 GHz wireless communications applications and wireless gadgets. [ABSTRACT FROM AUTHOR]

This research article reports a six-element multiple-input-multiple-output (MIMO) antenna for high-speed IoT, imaging, and Radar applications. The single-element UWB-X band antenna is designed and fabricated with asymmetric feed to achieve wider impedance-matched bandwidth. The antenna geometry is placed in planar on the 12-side polygon. A novel decoupling structure is used along with the ground plane which provides better isolation between each antenna and the antenna occupies an area of 8086mm2. The proposed 6 × 6 MIMO antenna design achieves measured bandwidth of 2.72–14.0 GHz. Also, prototypes are fabricated and full-wave simulation with experiment has been performed where S-parameters (reflection and transmission coefficients), the maximum peak gain of 6.65dBi, radiation pattern (stable), and diversity performance including ECC < 0.045, DG > 9.990 dB, TARC < −40 dB and CCL < 0.30 b/s/Hz has been evaluated. [ABSTRACT FROM AUTHOR]

This paper reports multiband microwave access multiple-input-multiple-output (MIMO) four-port antenna for UWB-X (3.10–12.0 GHz) band applications radiating electromagnetic energy with dual notched bands and compact size of 0.68λo × 0.92λo. Two notched bands are introduced on the radiating patch of the antenna and microstrip feed line mitigating Wireless-Local-Area-Network (WLAN: 5.11–5.88 GHz) & Downlink-Uplink Satellite (DUS: 7.28–8.36 GHz) interference. The technology reported includes simulated results and is validated by comparing the measured results of the 4 × 4 MIMO antenna. The mutual coupling between the radiating patch is suppressed below −15.0 dB which is achieved by interconnecting the ground and placing a cross-shaped parasitic patch between the radiating elements. The proposed MIMO antenna offers maximum gain efficiency of 5.92dBi & 0.95 (95%), respectively. The diversity parameters (ECCmax = 6 × 10−4, DGmax = 9.99 dB, TARCmax = −27.0 dB, CCLmax = 0.015b/s/Hz, MEG $ \approx $ ≈ −3.0 dB) are in the permissible range given by International Telecommunication Union (ITU) for information and communication technology. [ABSTRACT FROM AUTHOR]

In this article, a design of two-layered, dual circular-polarization (CP) and dual-band path antenna is presented for BeiDou navigation satellite (BDS) system applications. A single 50-Ω Co-axial probe feeding arrangement is employed to achieve dual-band operation and it feeds both the antennas simultaneously. This mode introduces the CP radiation on both upper (RHCP) and lower (LHCP) operation bands. The impedance bandwidth is further widened by accommodating two semi-circular stubs on the top patch. The fabricated and experimentally validated prototype radiates at 1.82 and 3.45 GHz (center frequency). The upper and lower operating band exhibits right and left-handed CP radiations, which constructs dual-band operation. The fabricated prototype has a physical size of πr2 × 0.024 λg with an antenna profile of 2.38 mm (0.024 λg). The experimentally validated upper and lower bands impedance bandwidth with |S11| < −10 dB are 21.1% and 11.1%, respectively. The fabricated prototype is a good candidate to use in BDS applications. [Q2 [ABSTRACT FROM AUTHOR]

In this paper we describe a class of printed patch antennas that involve 3 metal layers completely integrated within a single dielectric, which are of very high efficiency and significant gain. The antennas presented have dual linear polarization and sufficient impedance matching bandwidth to be suited for sub-6 5G applications, producing advantageous antenna arrays monolithically integrated into a single planar PCB that are thin and lightweight. The feeding mechanism of the antennas is through an intermediate dedicated metal layer designed appropriately as a coupler, coupling the input power at the feeding ports of the structure to the antenna without a direct metal contact to the radiating patch. The multilayer design allows monolithic integration of multi-element combiners and phase shifters within the PCB of antenna arrays and results in compact monolithic scanning arrays. Theoretical full-wave simulations and measurements of fabricated prototypes are in very good agreement and validate the proposed designs. [ABSTRACT FROM AUTHOR]

A compact and novel semi-elliptical defected ground structure (SE-DGS) tapered microstrip line fed UWB antenna with band-notched characteristics integrated with Ku and K band applications is proposed. The proposed SE-DGS UWB antenna is printed on a compact size of (15 × 18 mm2) and has radiation bandwidth of 25.66 GHz over a span of 4.11–29.77 GHz, a fractional bandwidth of 151.47%, and both the down link of X- and ITU-8 bands are completely notched over a span of 6.86–9.09 GHz using a single C-structured reflector. The proposed antenna has a fluctuating gain of 1.7–4.82 dBi except for the gain at the notched band frequency, which is −12.25 dBi. The proposed antenna has a high radiation efficiency of 96.23%, stable radiation patterns over the UWB range, and a high rejection capability of the notched band, which is noticed from the high value of VSWR of 23.15, making it a potential candidate for UWB, Ku, and K band wireless applications with effectively suppressed downlink of X and ITU-8 bands. The developed antenna design simulates breast cancer tissue detection by comparing S21 results, and specific absorption rates with and without tumour scenarios. These results suggest that the proposed radiator and system detect breast tumours efficiently. [ABSTRACT FROM AUTHOR]

In this paper, a planar reflectarray antenna is designed. The designed structure consists of new types of metamaterial unit cells. Two different flower-like shaped unit cells were studied at the center frequency of 12.5 GHz. The reflectarray contains multi cells with varying sizes of flowers. A metal plate and an air gap layer are placed behind the metamaterial sheet. A standard Ku band horn antenna feeds the structure. The F/D ratio is unity for the designed reflect array. Compared to previous reflectarray antennas, the designed reflect array consists of a limited number of cells, i.e. 121. Also, a new method without any try-and-error process is presented. The width of the designed reflector is so compact. This proposed method can be used for a reflectarray antenna with gain in the range of 20 to 30dBi with acceptable radiation efficiency. The CST software is performed to simulate and optimize the proposed structure. There is a good agreement between simulation and measurement results. [ABSTRACT FROM AUTHOR]

Vivaldi tapered slot antenna (VTSA) families are low-cost, lightweight, and have a simple design structure with good electrical performance and consistent impedance over a wide frequency range. It can be fabricated on a fragile substrate to be used for various applications like an aircraft wing or in wearable networks. One biggest issue with this antenna is impedance matching. In this design, an antipodal Tapered slot antenna is used. The proposed antenna's feed structure used a SIW (Substrate Integrated Waveguide) to microstrip transition. It allows us to design the characteristics of an antenna on a common substrate while maintaining a high-quality factor. The structure is simulated in CSTMWS (CST Microwave Studio) and the equivalent circuit of the transition part is also evaluated using ADS software tools. The operating frequency range of the structure is between 8 and 12 GHz (X band). This band has potential uses in radar, imaging, medical, space communication, and military applications. The whole structure is fabricated on the RO4003c substrate and measurements are taken with a VNA. The simulated and measured results are found to be very close to each other. The designed structure has a 40% percentage bandwidth and the overall dimension is 33 × 14 mm2. [ABSTRACT FROM AUTHOR]

An optically transparent antenna fed by a coplanar L-probe is proposed in this paper. Indium-doped tin oxide (ITO) with a sheet resistance of 3.5 Ω/sq etched on a soda-lime glass substrate is used as radiation array and ground to achieve high optical transmittance. TM $ _{10} $ 10 and TM $ _{20} $ 20 modes are excited simultaneously to expand work bandwidth. The fabricated antenna achieves a –10 dB reflection bandwidth of 27.5% from 4.7 to 6.2 GHz with the overall size of 42 mm × 42 mm × 3.3 mm. Different from many antennas composed of ITO, the proposed antenna exhibits directional radiation patterns with the maximum realized gain of 4.6 dBi and the maximum efficiency of 61%. Meanwhile, the optical transmittance of the antenna can reach above 58%. [ABSTRACT FROM AUTHOR]

In this paper, a single-layered broadband circularly polarized MIMO antenna is presented for a 5 GHz wireless local area network (WLAN). The Metasurface is designed with an array of patches and these patches are excited by four uniform aperture CPW feed MIMO antennas. The stubs are added across the aperture and central patches at respective apertures are increased to achieve broad bandwidth. Truncated corner square patches are used for the metasurface to achieve circular polarization (CP). The CP MIMO antenna has achieved an impedance bandwidth of 33% (4.35 GHz-6.08 GHz), a 3 dB axial ratio (AR) bandwidth of 11.95% (5.18 GHz-5.8 GHz) and a gain of 8dBi. [ABSTRACT FROM AUTHOR]

In this work, a novel triband antenna is developed for wireless local area network (WLAN), worldwide interoperability for microwave access (WiMAX), and Bluetooth application. The proposed antenna is printed on a low-cost FR-4 substrate and has an overall size of 25 mm × 40 mm × 1.6 mm. Coplanar waveguide (CPW) line with characteristic impedance of 50 Ω is used as feed for the designed antenna. A prototype of this antenna is fabricated and tested to validate the simulation results. The measured result shows that the antenna has the triple-band response with frequency bands that correspond to S11<−10 dB 2.36 − 3.17, 3.8 − 4.35, and 5.69 − 6.02 GHz. The measured gains of the antenna at resonant frequencies of 2.61, 4.115 and 5.85 GHz are 0.756, 0.925 and 1.589 dBi, respectively. Maximum decrement in measured gain is only 0.671 dB which is attributed to losses from connectors and cables. A novel approach, based on a combination of a cap-shaped ground plane and gap coupling technique in the form of an interdigital capacitor (IDC), is used to achieve the characteristic of triple frequency bands. Finally, the utility of the proposed antenna is checked with a four-element MIMO antenna. [ABSTRACT FROM AUTHOR]

A compact ultra-wideband Multiple-Input-Multiple Output (MIMO) Monopole antenna is proposed for frequency-notched applications. The proposed MIMO antenna consists of two identical Monopole antennas excited by two microstrip feeds. A stub is attached to the ground plane to improve isolation and impedance bandwidth. A quarter wavelength spur line is embedded on the feeding part of the antenna to achieve the notch frequency. The designed antenna exhibits −10 dB impedance bandwidth, covering the entire UWB spectrum. The L-shaped spur line contributes to the notch frequency at 5.5 GHz aiming to avoid interference from 5 to 6 GHz WLAN band. The planned model is fabricated and described in terms of impedance and radiation constraint measurements, compliant with those of results achieved from full wave simulation. [ABSTRACT FROM AUTHOR]

A wideband quasi-Yagi antenna with symmetrical rectangular slots in the ground plane is studied. The feeding structure of the antenna is simplified, consisting of a microstrip transmission line and a short strip. The driver and director arms are designed as half on both sides of the substrate to improve pattern stability. The antenna's bandwidth is improved by symmetrically adding rectangular slots to the ground. The antenna works between 3 and 7.7 GHz with a gain that varies between 4.7 to 7.4 dBi, a bandwidth of 87.8 % , and an efficiency of more than 90 %. The antenna has a very compact size of 0.42 λ L × 0.42 λ L ( λ L is the wavelength for the lowest operating frequency). The simulation and measurement results are in good agreement. The antenna has highly stable end-fire radiation within its operating frequency and can be used for wideband wireless communication systems. [ABSTRACT FROM AUTHOR]

A technique employing the use of directly coupled stacked patches to increase impedance bandwidth with reduced cross-polarization is proposed in this paper. The top stacked multi-resonator configurations are directly excited by employing metallic shorting posts (vias) between the metallic patches. In stacked directly coupled MSA, a bandwidth of 25.8% and a gain of 8.8 dBi with a gain variation of ±0.2 dB over the band are achieved. The cross-polar levels for this configuration are less than −15 dB and −5 dB at lower and upper frequencies, respectively. To suppress the cross-polar components, a symmetrically direct-coupled stacked MSA design is proposed. In this configuration, a bandwidth of 26.1% and a gain of 9.3 dBi with ±0.3 dB variation over the entire bandwidth are achieved. The cross-polar levels are significantly suppressed up to −25 dB and −16 dB at lower and upper frequencies, respectively. The proposed antenna configurations are designed and fabricated. The experimental results agree with the simulated results. [ABSTRACT FROM AUTHOR]

In this article, a metal-only reconfigurable reflectarray antenna (RRA) is proposed for generation of diversified circular-polarization (CP) focused beams and mode-agile vortex beams in the X-band. The proposed RRA element has the 3-D metal-only configuration, which consists of three staircases with different heights, a turntable, a latch, and a base. By rotating the proposed RRA element in 45° steps, the ability of 1-bit phase quantization with orthogonal linear polarization (LP) reconfigurability can be realized. Then, a 26 × 26-elements reconfigurable reflectarray antenna feeding by a linear polarization horn antenna is designed to enable free conversion of line-to-circle polarization at the array level. Full-wave simulations show that the diversified circular-polarization beams can be synthesized by adjusting the aperture element distribution. Furthermore, a manually reconfigurable reflectarray antenna prototype is fabricated to obtain the actual performance of the synthetic LHCP focused beams. The measured maximum gain of the LHCP beams is 27.1 dBi, with the aperture efficiency of 24.2% where the beam point at 20°, and the 1-dB gain bandwidth is 18.0% (9.3 GHz − 11.1 GHz). Finally, mode-agile vortex beams can also be realized by using the proposed reconfigurable reflectarray antenna, and the simulated results show that the mode purity of vortex beams are all above 35% in different modes, and the maximum gain of the vortex beams is 21.1 dBi, with aperture efficiency of 6.1% where the mode of vortex beams is −1. [ABSTRACT FROM AUTHOR]

The Sierpinski Gasket fractal antennas can provide the best generic multiband behaviour among the several planar feed monopole antennas available for use in automotive applications. The Gasket geometries used in antennas can be classical, scale perturbed, or both scale and flare perturbed. When used in the planar feed configuration, the classical and perturbed Gasket fractal antennas suffer from considerable reflections at one or more multiband frequencies, rendering these frequencies unsuitable for usage. Therefore, a design modification in these antennas is essential. A novel design modification has been proposed in the Sierpinski Gasket fractal antennas in the present research work by utilizing metamaterial engineered substrates. It has been found that the metamaterials not only reduce reflections but these materials also lower Gasket antenna frequencies, thereby, facilitating reduction in the antenna size. The findings have been validated through the experimental investigations. The comprehensive design analysis presented in the present paper shall prove highly beneficial to the antenna designers in rapidly customizing the vehicular antennas. [ABSTRACT FROM AUTHOR]

In this article, a polarization reconfigurable concentric circle microstrip antenna with simultaneous frequency agility has presented. The frequency agility and polarization reconfigurability have been controlled by open stub cascaded branch-line coupler (OSCBLC) feed network configuration. The −10 dB tunable impedance bandwidth of 2.0 GHz to 3.0 GHz (40%) is achieved by varying the capacitance of four varactor diodes from 4.15pF (0 V) to 0.84pF (7.5 V). These varactor diodes are fixed between the circular patch and ring. The polarization is reconfigured by directing the input RF through a single pole 4 throw (SP4 T) and routed to a single pole double throw (SPDT) switch in the feed network configuration. The right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP) are realized in the antenna by exciting the feed ports with a time phase difference of ± 90°. Similarly, the vertical linear polarization (V-LP) and horizontal linear polarization (H-LP) are attained in the antenna by excited any one port through the feed network. The impedance bandwidth (1.5 GHz to 3.5 GHz) of OSCBLC feed network configuration is well-matched with the agile wide impedance bandwidth of the designed antenna. The proposed designed antenna shows good agreement between simulated and measurement results for polarization reconfigurability and frequency agility. [ABSTRACT FROM AUTHOR]

In this paper, computer-aided design methods are used to optimize Cassegrain antenna dimensions in the case that the feed antenna is placed exactly behind the main reflector. Conical corrugated horn antenna is utilized as the feed antenna. Parabolic reflector antenna dimensions are calculated considering link budget initially. Then to reduce blockage effect due to the presence of subreflector in front of the main reflector a mathematical equation is extracted. Considering the complexity and nonlinearity of this equation, we used a numerical method to solve it, and optimum edge angle of the rays emerging from the feed antenna toward the subreflector is obtained. The other geometric parameters of the structure are then specified using the relations governing the structure. A design example is presented that clarifies the method more obviously. In this example, the slant ratio of the horn is chosen arbitrarily equal to 0.2. This example is simulated using FEKO software to verify the theory. Then to investigate the effects of choosing different slant ratio values on the Cassegrain antenna specification, the extracted mathematical equation is solved for different slant ratio values for the design example. Magnification factor, subreflector diameter, and the slant radius of the feed antenna are then calculated in optimum for distinctive slant ratio values, and the results are presented. [ABSTRACT FROM AUTHOR]

In this paper, a broadband circularly polarized array antenna is presented, which consists of four loop slot antennas based on metasurfaces. The antenna element is a loop slot antenna fed by a microstrip line. Cross slots are added to the loop slot to improve the antenna bandwidth, and four corner-cut square metasurfaces are loaded above it, thus generating circularly polarized radiation. The antenna adopts a sequential phase (SP) feed network to realize broadband characteristics. The antenna has been fabricated and experimented. The overall size of the antenna is 78 × 78 × 10.1 mm3 (approximately 1.22 λ0 × 1.22 λ0 × 0.15 λ0), the antenna array has a measured |S11| < −10 dB bandwidth of 3.6–6.2 GHz (53.1%) and a 3-dB axial ratio bandwidth of 3.7–4.8 GHz (28.32%). Furthermore, the antenna also has radiation with a peak gain of 5.5 dBi. [ABSTRACT FROM AUTHOR]

This paper presents a wideband planar filtenna based on the filter synthesis technique. The proposed filtenna consists of a third order hairpin line resonator filter coupled with an elliptical antenna. One arm of the last resonator of hairpin line resonator along with the extended feed arm of an antenna constitute an admittance inverter, which provides better integration between filter and antenna. The measured results show that the proposed filtenna exhibits a filtering response with impedance bandwidth of 26.5% (4.19–5.47 GHz), flat passband gain, good selectivity at band edges and omnidirectional radiation pattern well suited for WLAN application. [ABSTRACT FROM AUTHOR]

Broadband and the high gain circularly polarised antenna are designed in a single-layered planar substrate. An array of 3 × 3 truncated corner square patches are designed as a metasurface antenna on one side of the substrate and the metasurface antenna is fed by a stub-loaded uniform aperture CPW feed on another side of the substrate. In the metasurface antenna, the size of the central patch is increased for improving the bandwidth of impedance bandwidth and 3 dB axial ratio. Furthermore, the amount of truncation is reduced in the patches surrounding the central patch to enhance the bandwidth of impedance bandwidth and 3 dB axial ratio bandwidth. The designed metasurface antenna has achieved an impedance bandwidth of 38.2% (4.5–6.63 GHz) with an axial ratio bandwidth of 13% (5.0–5.7 GHz). Moreover, the antenna has a peak gain of 10.36dBic. The simulation and measurement results are compared. [ABSTRACT FROM AUTHOR]

For integrated design of a filter and an antenna, a wideband circularly polarized (CP) dielectric resonator antenna (DRA) with filtering characteristics is proposed. A rectangular slot structure is etched on the ground to optimize the axial ratio (AR) bandwidth of the antenna singly fed by one port. Capacitive filtering branches are combined into the microstrip feeding line to effectively generate two radiation nulls outside the passband. To further enhance the suppression level in the high-frequency stopband, the stair-shaped DR is chamfered into a fish-shaped structure. A suppression level larger than 15 dB is found within the stopband. A prototype of the antenna is fabricated, and both of the simulated and measured results show a wide bandpass filtering performance over the operating frequency band. The antenna has an impedance bandwidth of 37.8%, an AR bandwidth of 25.1%, and a low profile of 0.078λ0 (λ0 is the free-space wavelength at 5.47 GHz), which can be a good candidate for 5 G and WLAN communication systems. [ABSTRACT FROM AUTHOR]

Wireless network becoming an integral part of daily existence, and it is expected to become much more so in the future. The dual-band frequency-reconfigurable H-shaped microstrip antenna fed by two coaxial probes is presented. The two modes for textile applications, the antenna is symmetrically filled with back-to-back attached zener diodes. The first mode's tuneable range is between 2 GHz and 2.5 GHz, while the second mode's range is between 1.5 GHz and 4.8 GHz. The suggested antenna's radiation can be switched from two orthogonal linear polarizations in the 1.5 GHz to 2.5 GHz range by adjusting the capacitance of the zener diodes. The HFSS is used for designing and simulating the antenna and antenna performs well in terms of Voltage Standing Wave Ratio [VSWR], Return Loss, directivity, and cross-polarization. The antenna is constructed on a 70 mm × 50 mm with FR4 epoxy dielectric substrate; switch scale of 0.8 mm × 1.6 mm and 3.58 is relative permittivity with substratum height of 1.6 mm. [ABSTRACT FROM AUTHOR]

Development and optimization of new waveguide polarizers with conducting stepped-thickness septum were performed in the article. Matching and polarization performance of novel microwave devices were accurately modelled using numerical finite elements method. An experimental prototype of the developed waveguide polarization converter with the suggested configuration of a septum was manufactured and measured. It was demonstrated that the application of a stepped-thickness conducting septum with 3 sections instead of a constant-thickness conducting septum improves return losses and cross-polarization isolation of the square waveguide polarization converter by 5 and 7 dB, respectively. In addition, measured cross-polarization isolation of the developed septum waveguide polarizer in an assembled antenna feed network is > 30 dB. Therefore, designed compact stepped-thickness septum polarization converter can be effectively applied in modern dual-polarization antenna systems for satellite communications and radar appliances. [ABSTRACT FROM AUTHOR]

A composite antenna with wide impedance bandwidth and enhanced isolation for multiple-input-multiple-output (MIMO) applications is introduced in this article. A simple conformal-strip fed rectangular dielectric resonator (rDR) with a conducting conformal-patch, which provides wide impedance bandwidth (3.21-6.19 GHz), is utilized as an antenna element. The proposed MIMO antenna is formed by arranging two symmetrical composite antenna elements side by side along with a simple decoupling structure (based on a wide rectangular slot and two metallic strips) in between them. The proposed MIMO antenna delivers good inter-port isolation (greater than 18 dB) over the entire operating bandwidth. Also, a well satisfactory outcome of the envelope correlation coefficient (ECC) is obtained over this bandwidth. Moreover, the proposed antenna exhibits a stable broadside directional radiation pattern over the entire operating bandwidth. [ABSTRACT FROM AUTHOR]

A compact circularly polarized (CP) square slot antenna fed by a microstrip line is proposed. This design comprises a square slot on the top of the substrate and a stubbed microstrip line on the back of the substrate. The results indicate the 45.61% impedance bandwidth (2.86 to 4.55 GHz) and 32.74% axial ratio bandwidth (3.27 to 4.55 GHz) with 3.94dBi peak gain over the entire CP band. Furthermore, an attempt has been made to obtain the unidirectional radiation patterns with almost twice peak gain by employing a metallic reflector at a distance of quarter wavelength beneath the ground plane of proposed antenna. [ABSTRACT FROM AUTHOR]

A compact wideband three-unit implantable multiple-in-multiple-out (MIMO) antenna for biomedical applications is proposed in this paper. By loading a "Y" slots on the radiation patch, and a metallized via between the radiation patch and the ground plane, they are jointly designed to reduce the Q value of the antenna unit and improve its bandwidth. At same time, three "wolf-teeth club " slots with filtering characteristics are introduced into the ground plane to isolate the coupling of ground surface current at feed ports of antenna units, so as to improve the isolation between feed ports. The 10 dB bandwidth of the MIMO antenna unit is 1.21 GHz-1.66 GHz, covering the commonly used Wireless Medical Telemetry Services (WMTS) band (1.427–1.432 GHz). And the isolation between units is more than 29 dB in the whole 450 MHz bandwidth, among which the isolation in WMTS band are more than 31 dB. Compared with other implantable MIMO antennas, this design not only integrates more MIMO antenna units in a small area but also each MIMO unit has broadband characteristics. [ABSTRACT FROM AUTHOR]

The novel ridge-gap waveguide (RGW) technology which has recently been introduced has many advantages in micro/mm-wave frequencies such as low loss, broad bandwidth, low sensitivity to manufacturing errors and easy integration with active components, etc. In this paper, a Ku-band 8-way Wilkinson power divider (WPD) is proposed and simulated based on the RGW technology for the first time, to the best of our knowledge. An RGW-toWR62 transition is also designed and simulated. The proposed 8-way RGW-based WPD with WR62 transitions shows low-loss equal-power division in phase with good matching at all ports and isolation between output ports in the Ku band. The proposed RGW-based WPD can be extended to an arbitrary 2 N -way corporate power divider/combiner which can find many applications such as in array antenna feed networks, solid-state power amplifiers (SSPAs), etc. [ABSTRACT FROM AUTHOR]

A high-resolution near-field focusing metasurface lens (MSL) was proposed to meet the high-resolution and miniaturization requirements of focusing devices in the Ka-band passive millimeter wave (PMMW) imaging system. Based on coaxial ring structure with polarization insensitivity, the design of a single refraction surface phase gradient MSL capable of focusing on plane waves is completed. Furthermore, the near-field focusing is realized by the method of phase superposition. The overall size of the lens s is 80 × 80 mm2, composed of 25 × 25 unit with the thickness of only 0.24λ. The feed source used a tapered slot antenna based on substrate integrated waveguide. The simulation results indicate a good spatial resolution of the presented lens, which can focus the electromagnetic wave radiated from the feed antenna at 70 mm with the focal spot size of 9 mm. The lens can effectively reduce the system volume and achieve high resolution imaging when utilized in PMMW imaging system. [ABSTRACT FROM AUTHOR]

A novel multibeam slot antenna using metasurface is presented in this communication. This antenna is fed by a coupling aperture and its radiating element consists of dual-layer metasurfaces formed by different units. By employing the rectangular loop slot as the coupling aperture, a wide impedance bandwidth is obtained. Meantime, a dual-layer cross-placed checkerboard metasurface is utilized to generate four beams and expand the operation bandwidth. The experimental results demonstrate that the antenna has a bandwidth of 1.37 GHz (2.18–3.55 GHz). Moreover, the four beams point at (φ, θ) = (180°, 23°), (270°, 23°), (0°, 23°), and (90°, 23°) and the maximum gain reaches 7.63 dBi. [ABSTRACT FROM AUTHOR]

Dielectric properties of Li2Ti1-x(Co1/3Nb2/3)xO3 (x = 0.1–1.0) ceramics using a solid-state reaction method were investigated. Substitution ratio effects on different phase changes and dielectric characteristics of Li2Ti1-x(Co1/3Nb2/3)xO3 (x = 0.1–1.0) ceramics were improved because of the solid solution of (Co1/3Nb2/3)4+ substitution in a Ti site. Therefore, optimal microwave dielectric properties (εr ~ 21.3, Q × f ~ 110,000 GHz, τf ~ 0 ppm/oC were achieved for Li2Ti0.7(Co1/3Nb2/3)0.3O3 ceramics sintered at 1150°C for 3 h, which is thus a favorable material for dielectric substrate applications involving a monopole antenna. The monopole antenna fed by a microstrip-line was printed on Li2Ti0.7(Co1/3Nb2/3)0.3O3 ceramic substrate. [ABSTRACT FROM AUTHOR]

Wireless body area network (WBAN) is a progressive field of research that allows the transmission of biological signals from user's body to an off-body control device. Compact antennas with stable on-body behaviour are achieving interest for WBAN. Here, a CPW fed antenna with L-shaped ground and radiator is investigated for dual-band operation at 2.45/5.8 GHz Industrial Scientific and Medical (ISM) bands. A metallic plate is added below the antenna to tune the impedance for dual bad operation as well as it improves antenna gain and efficiency on body-tissue. Proposed structure is analysed to work in the close region of body by using a rectangular three-layered tissue phantom while simulation and on pork loin while measurement. Measured |S11| of −20 dB is achieved for both the operating bands. Wide bandwidth of 310 MHz at lower band and 330 MHz at upper and makes antenna suitable to cover the desired operating bands even after structural deformation. Antenna has maximum radiation efficiency of 50% and 32%, directivity of 6.15dBi and 8.5dBi, broadside and unidirectional radiation characteristics at 2.45/5.8 GHz, respectively. [ABSTRACT FROM AUTHOR]

Poly-spirals are composed of contiguously interconnected spiral elements and are ubiquitous in the monuments of various cultures since prehistoric times. In adopting poly-spiral geometries for antenna applications, we may in general choose these contiguously connected spirals to be identical or dissimilar, such as by selecting them to be of circular, eccentric, or polygonal shape. We focus on a special class of poly-spirals with circular elements, namely the Celtic-Archimedean spiral. We subsequently compare its radiation properties with those of a regular circular Archimedean of the same size and number of turns. The Celtic-Archimedean spiral could be used as a pattern and polarization diversity reconfigurable antenna due to its feeding mechanism. We compute the diversity gain provided by the Celtic-Archimedean spiral when used in a WLAN network operating at 2.4 GHz. [ABSTRACT FROM AUTHOR]

A circularly polarized monopole antenna fed by coplanar waveguide is presented in this research. The antenna operates in wireless local area network and worldwide interoperability for microwave access bands. Circular polarization (CP) is achieved by using inverted L-shaped strips on both sides of a simple monopole and introducing asymmetries in the ground plane. The measured impedance bandwidth from 1.77 to 5.35 GHz while axial ratio bandwidth from 2.04 to 3.85 GHz are achieved. The proposed antenna has a gain of 0.6–2.8 dBi within the circular polarization band. [ABSTRACT FROM AUTHOR]

A sidelobe-suppression technique for the reflector antenna is proposed. Compared to the conventional reflector antenna analysis technique, the proposed technique adopts the novel quasi-actual feed instead of the traditional imaginary feed to calculate and optimize the radiation pattern of the reflector antenna. The calculated and the optimized radiation results obtained by the proposed technique are more accurate since the quasi-actual feed data is closer to that of the practical feed. In the proposed technique, the sidelobes are suppressed by optimizing the shape of the reflector illuminated by the quasi-actual feed. The reflector shape is smoothly transformed by the non-uniform rational B-spline technique and the scatter of the reflector is efficiently calculated by the physical optics and the Gauss-Legendre quadrature algorithms. The pattern result of this proposed technique is compared with the result simulated by FEKO software, a good agreement is achieved and has a higher efficiency. As an example of applying the proposed technique, an unshaped and a shaped reflector antennas with the same feed and the same size are designed, fabricated and tested, and the measured results agree well with the expectations on the low sidelobe characteristic. [ABSTRACT FROM AUTHOR]

This paper proposes a dual-polarized cavity-backed Vivaldi antenna with wide bandwidth for telemetry system. The designed dual-polarized antenna is composed of two orthogonal printed dipole antennas, and each polarized antenna is fed by Non-Coplanar Strip line. A wideband Balance to Un-balance transformer (Balun) is employed to connect the input microstrip transmission line with the antenna Vivaldi radiator. The designed feeding structure makes the two antenna substrates to be directly mounted and the occlusion problem is resolved, and the port isolation is also improved. A cylindrical metal cavity is introduced to enhance the radiation pattern and efficiency. The dual-polarized antenna can be operated in the frequency band of 1.9–2.5 GHz, which covers the band frequencies of the designed telemetry system. The simulated results through the full-wave electromagnetic simulation technique show that the gains of two polarization ports are higher than 6.9 dBi at central frequency. A prototype with dual linear polarization has been fabricated for validation. Both the simulation and measured results show that the proposed antenna has a bandwidth of 27% when the voltage standing wave ratio is less than 2 with desirable directional radiation patterns as well as high isolation better than −25 dB between the two input ports. The antenna scheme proposed in this paper is suitable for the telemetry system application. [ABSTRACT FROM AUTHOR]

A low-profile multi-input-multi-output (MIMO)/diversity antenna suitable for wireless local area network (WLAN) applications is presented. In the proposed antenna, two identical elements (each of size 20 × 47 mm2) are designed to operate at 2.4 GHz and other two identical elements (each of size 20.5 × 20 mm2) at 5.8 GHz. All elements of the proposed diversity antenna are printed on 1.6 mm thick FR-4 substrate in a coplanar configuration. By optimizing the distance between the antenna elements (in horizontal and vertical directions), optimal isolation and diversity performance are achieved. Compared to a single feed dual-band antenna, the MIMO/diversity antenna has the ability to transmit or receive the 2.4 and 5.8 GHz signals simultaneously, without any external switching circuit between the module and the proposed antenna. [ABSTRACT FROM AUTHOR]

This paper presents a novel high gain rectangular microstrip patch antenna (RMSA) with vertically placed Yagi elements. The antenna is fed by a coaxial probe to excite TM01 fundamental waves at 2.4GHz, which is suitable for wireless local area network (WLAN) applications. In order to increase the antenna gain, Yagi elements are placed in groups of 5, on each side of the substrate in order to serveas directors for the radiating slots as well as the ground reflections. The proposed antenna offers 1.3dB gain improvement and %3.1 impedance bandwidth increase in comparison to the plain rectangular microstrip antenna with the same specifications. The advantage of this antenna is to provide an easy and cost effective solution to increase microstrip antenna gain, particularly in 8-10dB range, without disruptingits planar structure. [ABSTRACT FROM AUTHOR]

In this paper we propose an end-fire antenna fed by a spoof surface plasmon transmission line that can exhibit a conical directional response. The plasmonic transmission line is composed of metallic strips of periodic sawtooth grooves that taper towards the firing end of the strip. By tapering the sawtooth grooves, reflection is suppressed, and a high gain is achieved when the spoof surface plasmons radiate into free space. Simulated results indicate that our antenna can achieve high efficiency and a maximum gain of 12.4 dBi within a wide operating band from 6 to 13 GHz. The antenna proposed in this paper has a simple and compact structure with a lateral dimension of approximately 0.19 λ 0 * 0.32 λ 0 and shows great potential for use in spoof surface plasmon polariton communication systems along with integrated circuits. [ABSTRACT FROM AUTHOR]

Today, multimode antennas for MIMO (multiple-input multiple-output) systems have been used extensively to develop capacity or to improve the quality of WIFI. Due to the orthogonality of characteristic modes, the theory of characteristic modes used to achieve minimum interference between channels is common in this type of antennas. In this paper, a four-port antenna with symmetric structure is presented on a circular patch to be able to produce four orthogonal patterns with extremely low correlation coefficients (less than 0.001) and high gain in the frequency range of 4.4–5.2 GHz and SWR <1.22, which is highly efficient in creating independent and simultaneous communication paths in MIMO systems. To create this orthogonality and decrease the correlation between channels, the characteristic modes method is used. Circular polarization can be obtained by changing feeding structure in this antenna. [ABSTRACT FROM AUTHOR]

In this article, compact coplanar waveguide feed antenna covering ultra-wideband and X-band signals (2.98–13.34 GHz) is presented. Antenna also offers triple-notched band elimination (Wireless Interoperability for Microwave Access: 3.40–3.95 GHz, Wireless Local Area Network: 4.50–6.34 GHz and Downlink Satellite System: 7.11–7.802 GHz) which is due to insertion of stub and etching of slots. Antenna is fabricated and characterised on silicon for imaging and wireless applications having a fractional bandwidth of 133%. The antenna offers gain, radiation efficiency and group delay between 3.26 and 8.00 dBi, 84% and 92% and ≤±1.0 ns, respectively, for the entire bandwidth. Isolation of antenna in face-to-face and side-to-side orientations is <−25 dB with very less distortion presented in the transmission and reception of the signal. The radiations emitted by the antenna are observed as a dipole-like pattern in E-plane and omnidirectional in H-plane. [ABSTRACT FROM AUTHOR]

In this paper, a wideband, wide-scan, low-profile antenna array of electrically small monopole antennas is proposed. The array is designed for L-band applications. An electrically small antenna with an in-built feed and matching network is proposed as an unit element of the phased array. The size of the unit cell is 0.15 λ × 0.21 λ × 0.07 λ where λ is free space wavelength at 1 GHz. The array is designed taking into account strong mutual coupling between the elements. For the case of the infinite array, an impedance bandwidth of 45.7% is observed along with wide angle scanning of −50° to 50°. To analyse the performance of the finite array with mutual coupling, a prototype of 4 × 4 element finite array has been simulated and fabricated. For the finite array, more than 80% efficiency is observed throughout the band of interest. The prototype of the proposed array is fabricated and tested. A significant match is observed in measured and simulated results. [ABSTRACT FROM AUTHOR]

A new structure for wideband circularly polarized (CP) slot antenna is proposed in this article. The designed antenna consists of a circular patch with two rectangular slots, which are parallel to CPW feed line, excites two resonance modes for wideband performance. To achieve CP operation, an inclined coupling slot loaded feed line on the ground is used. Furthermore, the proposed antenna is an enhanced version of earlier wideband CP antennas having a compact structure with a low-profile of 0.023λo (λo stands for the free space wavelength at 4.46 GHz) and ground size of 30 mm × 30 mm. It operates over the impedance bandwidth of 88.9% (relative to the center frequency of 4.5 GHz) and 3-dB axial ratio bandwidth found for this band is 2.7% (relative to the center frequency of 4.46 GHz). To verify the performance of the designed antenna, the experimental results match well with the simulated results. [ABSTRACT FROM AUTHOR]

This article presents the design of a wideband corrugated conjugate matched feed horn to cancel the high unwanted cross-polar components generated in offset reflector geometry having very low F/D and high offset angle. A new kind of symmetrical cascaded discontinuities is used in circular waveguide at the throat section of the horn for wideband operation of corrugated conjugate matched feed. The feed horn is specifically designed to mitigate the cross-polarization generated in 90° offset reflector antenna system with F/D = 0.7 and 0.4. The secondary radiation patterns have been computed. Significant improvement in the cross polarization is achieved at 55–60 GHz frequency band. [ABSTRACT FROM PUBLISHER]