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In this paper, work on a Ganesha‐shaped semi‐transparent patch antenna is presented for its use in vehicular application. The design of the antenna is opted from a commercially available Ganesha sticker that is mostly placed on the vehicle's window panes as a symbol of an auspicious deity. The geometry of the sticker without any variation in its dimension is made to work as an antenna. The antenna is fabricated using adhesive copper tape on a glass slab backed by an AgHT‐8 transparent conducting sheet which acts as the ground plane. Microstrip inset feeding technique is used to excite the patch and its return loss performance and free space radiation pattern measurements are carried out. Measured results show promising performances that can be used in future vehicular applications and are in good comparison with that of the simulated results. [ABSTRACT FROM AUTHOR]

In this paper, a single‐layer filtering antenna based on half‐mode patches is proposed. It consists of a main driven patch and a parasitic patch. A U‐shaped slot is first etched on the main driven patch to generate a new resonant mode and a radiation null simultaneously. Four pairs of shorting pins are introduced on the main driven patch to raise its operating frequency to near that of the U‐shaped slot, thus broadening the impedance bandwidth (IBW). Additionally, a parasitic patch is introduced near the driven patch to introduce an extra half‐TM10 mode and an extra radiation null, significantly enhancing the IBW and the upper‐edge selectivity of the antenna. A prototype was fabricated and tested for validation. It achieves a peak realized gain of 6.55 dBi and −10‐dB IBW of 8.8%, and exhibits good out‐of‐band rejection performance while maintaining a low profile of 0.017 λ0 and a compact transverse size of 0.29 λ02. [ABSTRACT FROM AUTHOR]

In this paper, a dual‐polarized multibeam antenna in X‐band is designed and physically fabricated using a parabolic reflector. The antenna consists of a feed array and a metal reflector. A dual‐polarized microstrip antenna array combining two design approaches, T‐coupled feed and defective ground structure, is adopted as the feed array to improve polarization isolation. In addition, the electromagnetic bandgap structure is loaded between the antenna units to reduce the mutual coupling and improve the isolation between the units. A nine element of the highly‐isolated dual‐polarized microstrip antenna array is designed to be placed on the focal plane of the parabolic reflector as the feed, and the beam deflection is realized by using the lateral defocus effect of the parabolic plane, which can finally realize nine single beams covering a 30° scanning range in both horizontal and vertical polarization modes. Based on the scanning state of multiple point beams, this paper uses the Fourier series for beam assignment to form a flat‐top beam with a wide scanning angle. The application of the antenna with two operating modes of wide beam and multibeam to navigational satellite systems can greatly improve the accuracy and efficiency of navigation. [ABSTRACT FROM AUTHOR]

This paper presents a miniaturized broadband microstrip patch antenna with a simple geometry. The radiation patch of this antenna comprises two rectangular patches with slightly different sizes, one side of each patch is grounded by metal via‐holes. Two rectangular patches are connected by a microstrip line and fed by a single port. Two rectangular patches produce two closely resonant frequencies achieving broadband performance. This antenna operates on the resonant method of short‐circuiting on one side. Metal via‐holes act as a short‐circuit wall allowing each patch to operate in TM0.5,0 mode. The size of a 1/4 wavelength resonant patch is only half of a conventional microstrip antenna, the overall size of this antenna is almost as same as a conventional rectangular microstrip antenna, making it compact in size. The wideband is achieved by combining two radiating patches, resulting in stable radiation and flat gain. Measurement results show that the antenna has an impedance bandwidth of 4.35− $-$5.10 GHz (15.8%) using a common dielectric substrate without air layer thickness additionally. The maximum measured realized gain is 4.61 dB. This antenna has advantages of wide bandwidth, low profile, flat gain and ease of manufacturing. [ABSTRACT FROM AUTHOR]

The paper proposes a circularly polarized dual band single feed microstrip monopole antenna. The proposed antenna consists of a radiating patch, a shrink ground plane, and a 50 Ω microstrip transmission line feed. The radiating patch is a combination of three modified metallic strips, a modified rectangular strip and a semicircular strip. The ground plane consists of two modified open ended slots. The substrate area of the antenna is only 40 mm × 42 mm × 1.6 mm. The antenna has been designed by HFSS simulation software and after getting simulated results the antenna has been fabricated to verify its results. The antenna provides measured bandwidths (−10 dB impedance bandwidth) of 600 MHz (2.2–2.8 GHz) in the lower band and 2.1 GHz (7.5–9.6 GHz) in the higher band. The measured results show its 3 dB axial ratio bandwidth of 120 MHz (2.2–2.32 GHz) for lower band and 1.4 GHz (7.2–8.6) GHz for the upper band. The high measured peak gain of 8 dBi has been obtained from the proposed antenna. The lower band is useful for WiMAX application and upper band is useful for C band application. The desired radiation patterns (RHCP and LHCP) have been obtained from the proposed antenna. [ABSTRACT FROM AUTHOR]

In this paper, a circularly polarized metasurface antenna for microwave energy harvesting (MEH) is proposed. First, a 4 × 4 metasurface is analyzed and integrated with the microstrip slot based on characteristic mode analysis for broadband, low profile, and high gain metasurface antenna. The measured results show that the impedance bandwidth of the metasurface antenna is 1.82 GHz, the 3 dB axial ratio bandwidth is 0.96 GHz. Subsequently, a wideband rectifier for C‐band is fabricated and measured according complex impedance compression theory. The frequency of efficiency >50% is from 5.1 to 6.3 GHz with 17 dBm input power. Finally, the novel antenna and rectifier are connected as rectenna for MEH, which shows great potential due to the tunability of the polarization mode (right‐handed CP [RHCP]/left‐handed CP [LHCP]) and the flexibility of the structure. [ABSTRACT FROM AUTHOR]

In this paper, the radiative near‐field method has been employed to transfer power through a triangular patch microstrip array that had not been used for this application previously. Additionally, the FR4 substrate is utilized to further reduce the system cost. The system comprises two identical array antennas functioning as both transmitter and receiver. Each array consists of four triangular patches with a side length of 38.5 mm and operates at a frequency of 2.4 GHz. The distance between the two arrays is 50 mm, placing the system in the radiative near‐field category of wireless power transfer. This two‐array system enables the evaluation of power transfer efficiency. The system's performance is improved compared to that of a single triangular patch, and it is also studied in terms of changes in distance. As expected, reducing the distance enhances the system's performance. Subsequently, the structure is fabricated, and the measurements validate the simulation results. The simulation and measurement results exhibit good agreement. [ABSTRACT FROM AUTHOR]

A slotted microstrip patch antenna for fifth‐generation (5G) mobile applications is presented in this paper. The proposed antenna addresses the intrinsic narrow bandwidth of patch antennas by introducing rectangular slots in the form of a disjointed H‐slot to broaden the bandwidth. The patch design and the slots introduce two extra resonances to broaden the bandwidth of the antenna. An impedance bandwidth of 26.6% from 24.95 to 32.6 GHz was achieved. A measured peak gain of 9.44 dBi was also achieved with a minimum half‐power beamwidth of 36° over the entire bandwidth. The proposed slotted patch antenna is implemented on a 44.6 mm × 26.3 mm × 0.8 mm RT5880 Printed Circuit Board. [ABSTRACT FROM AUTHOR]

This paper presents a low‐profile and broadband pattern diversity microstrip antenna with quasiperiodic radiating patches fed by two slots. The thickness of the whole design is only 0.044λ0 (λ0 is the free‐space wavelength of the center frequency), showing great potential in applications. The broadband property is realized by efficiently exciting TM10 mode and antiphase TM20 mode and forming two resonant frequencies in the target band. The antenna can generate a broadside or difference pattern by switching the input port of the broadband 180° hybrid coupling feed network. The measured results show that the coincident impedance bandwidth of the antenna working in the two pattern modes is 20.5% (3.20–3.93 GHz), and the maximum gain values are 6.85 dBi for the directional pattern and 5.80 dBi for the difference pattern. [ABSTRACT FROM AUTHOR]

A compact, single‐layer, dual‐frequency patch antenna with large beamwidth diversity, that is, broad beamwidth in the lower frequency and high‐gain radiation in the higher frequency is presented and analyzed in this paper. The antenna is in general composed of a square driven patch and two T‐shaped top‐loaded monopoles that are loaded beside the two radiating edges of the driven patch. Herein, the patch antenna to be operated in the fundamental TM01 mode intrinsically provides a pair of in‐phase magnetic currents and meanwhile, the top‐loaded monopoles produce a pair of out‐of‐phase vertical electric currents. In analysis, consistent broad beamwidth and high‐gain radiation pattern are, respectively, well maintained at the lower and higher frequencies, even with a frequency ratio as small as 1.02. Moreover, the antenna preserves simple geometry and high efficiency of a typical patch antenna. For verification, a prototype is in final fabricated and measured, which has experimentally confirmed its simulated radiation results. [ABSTRACT FROM AUTHOR]

In this paper, a fractal antenna is proposed for wideband application. It has a resonance frequency of 5 GHz, and has been designed using an FR4 substrate with a width and a length of 40 mm and patch with a width, length of 35.288 mm. The proposed antenna has been made with five iterations, and the result obtained multiband behavior and agrees with the various efficient wireless applications. In the proposed antenna, there are four bands response at frequencies 1.6, 2.9,5.2, and 6 GHz, and bandwidth percentage are 4.56%, 7.89%, 12.13%, and 4.6%. It also covers application in 1.5–1.7, 2.8–3.1, 4.8–5.4, and 5.9–6.2 GHz. The gain and the directivity of the proposed antenna is measured as 15.885 dBi greater than other fractal antennas to date, and 7.422 dBi respectively. The proposed antenna has been implemented successfully using IE3D and the result has been tested successfully using a key sight vector analyzer. [ABSTRACT FROM AUTHOR]

Presented in this paper is a circularly polarized (CP) wide 45° rotated slot antenna with a broad bandwidth. Characteristic mode analysis is initially carried out to show that, by simply rotating a square slot, CP waves can be radiated if it is properly excited. A simple 50 Ω feedline is then designed to excite the slot for the generation of broadband CP waves. The antenna has a total volume of 30 × 30 × 1.6 mm3. Measurement results indicate a broad S11 ≤ −10 dB impedance bandwidth of 85.7% (3.2–8 GHz), a broadband 3 dB axial ratio bandwidth of 57.1% (3.5–6.3 GHz) and a peak gain of 3.6 dBi are obtained by the antenna. The proposed antenna possesses stable radiation patterns as well as relatively flat gain over its operational bandwidth in addition to being compact. It can thus be used for wireless technologies such as WiMAX 3.5 and 5.5 GHz, WLAN 5.2 and 5.8 GHz in addition to Industrial, Scientific, and Medical 5.8 GHz. [ABSTRACT FROM AUTHOR]

This paper reports the study of a tunable isolator based on a four‐strip resonant structure to reduce the mutual coupling between two patch antennas. Unlike other decoupling structures with a fixed center decoupling frequency, this design provides tunable mutual coupling reduction frequency response and adjustable mutual coupling level by integrating a varactor diode into the strip isolator. This study investigates the effect of the position and capacitance of the varactor diode on mutual coupling. In addition to tune‐ability, the tunable four‐strip resonator reduces the coupling level at all frequencies around 3.5 GHz by at least 6 dB to less than –28 dB without degrading the impedance bandwidth. Compared to the case with the four‐strip resonator structure but without the varactor diode, the isolation is further improved by 2 dB or more. The measured results are consistent with the simulation results. [ABSTRACT FROM AUTHOR]

This paper focuses on the design of a novel automatic‐dependent surveillance‐broadcast (ADS‐B) patch antenna operating at 1090 MHz with good bandwidth and good gain for aircraft tracking and navigation purposes. The structure of the proposed antenna consists of a long strip line ended by a crescent patch, a U‐shaped ground plane, and a rectangular substrate. The proposed antenna is simulated using both HFSS and CST electromagnetic simulators. The overall dimensions of the antenna are 130 × 26 × 1.6 mm3, and is fabricated on a low‐cost FR‐4 epoxy substrate. Various parameters are determined and analyzed to evaluate the antenna performance in terms of reflection coefficient, impedance bandwidth, radiation pattern, gain, and efficiency. It has been verified and tested that the simulated results are in very good agreement with the measured ones. At the desired frequency of 1090 MHz, the ADS‐B patch antenna has a gain of 2.23 dBi and a measured impedance bandwidth at −10 dB of 200 MHz. The antenna has an omnidirectional radiation pattern, which will allow the antenna to pick up ADS‐B signals broadcasted by aircraft in all directions. An ADS‐B system has been built and validated using aircraft data provided by the Flightradar platform. [ABSTRACT FROM AUTHOR]

A novel broadband ultra‐high frequency radio frequency identification (RFID) tag antenna attached to the metallic surface is proposed in this paper. A rectangular wide slot combined with a U‐shaped thin slot outside is adopted in the proposed antenna, and the size of the patch can be reduced by adjusting the length of the U‐shaped slot. Furthermore, a pair of symmetric resonator structures inside the rectangular slot are connected to both ends of the chip, which can excite a new resonant mode to broaden the frequency band. All the structures above are realized by etching rectangular slits on the same surface. The antenna has the advantages of wideband, simple processing, and good reading distance, and the 10 dB bandwidth of the antenna is 30 MHz (from 895 to 925 MHz), with a maximum directional gain of −3.5 dB. The reading distance can reach more than 5.4 m on a metallic surface. [ABSTRACT FROM AUTHOR]

Subminiature GPS L1 band (center frequency: 1575 MHz, wavelength [λ ${\rm{\lambda }}$]: 190 mm) microstrip antenna suitable for mounting in small electronic devices is proposed in this paper. The newly proposed antenna was transformed from the basic λ/2 microstrip patch antenna to a λ/4 microstrip antenna. To apply the perturbation theory, the width of the radiating element on the feeding point with strong magnetic field energy was narrowed. In addition, the open end of the radiating element with strong electric field energy was folded down in a "王" shape to reduce the antenna size. The size of the designed subminiature microstrip antenna is 10 mm (0.05λ ${\rm{\lambda }}$) × 9.5 mm (0.05λ ${\rm{\lambda }}$) × 8.5 mm (0.04λ ${\rm{\lambda }}$). For impedance matching, the position of the feeding point and the gap between the feeding line and the short stub were adjusted. The fabricated antenna obtained S11 ${S}_{11}$ of −17 dB at the center frequency of 1575 MHz. While the size of the ground plane was 48 mm (0.25λ) × 50 mm (0.26λ), the omnidirectional radiation characteristics for both Eθ ${E}_{{\rm{\theta }}}$ in the xz‐plane and xy‐plane with average gain of −0.3 and −1.7 dBi, respectively. A size reduction ratio of 98.9% was secured from the results compared to the basic λ/2 microstrip patch antenna. [ABSTRACT FROM AUTHOR]

This paper presents a magnetless nonreciprocal diplexing antenna that uses time modulation. The device combines the functions of diplexers, filters, isolators, and antennas in a highly integrated manner. The magnetless nonreciprocity response is achieved by applying time modulation to the resonators of the filtering structures. These resonators are implemented in quarter‐wavelength microstrip lines terminated with varactors that are time modulated by low‐frequency signals fed from Coplanar Waveguides built on the ground plane of the microstrip structure. A prototype multilayer patch antenna is fabricated, which is fed through two orthogonal feedlines and the radiating square patch is coupled by a square ring slot etched in the ground plane. The experimental results show that a gain of 4 dB, out‐of band rejection of 22 dB, in‐band isolation of 20 dB, and inter‐port isolation of 35 dB is obtained at both 1.5 GHz (lower band) and 1.8 GHz (higher band). [ABSTRACT FROM AUTHOR]

In this paper, a cavity‐backed semi‐circular antenna with rectangular slot for MIMO (multiple‐input multiple‐output) systems is presented. The proposed MIMO antenna comprises two rectangular slots etched on the ground plane and excited by two microstrip transmission lines. The substrate integrated waveguide (SIW) is integrated to enhance the isolation between the two antenna elements. The obtained results show that the antenna operates around 5.8 GHz with an impedance bandwidth between 5.65 and 5.9 GHz, with S11 ≤ −10 dB, which is suitable for WLAN (wireless local area networking) applications. The fractional bandwidth of the reference MIMO antenna is 4.13%, while for the SIW MIMO case attains 4.31%. Moreover, the integration of SIW resonators leads to an enhancement of the isolation from 17.7 dB (reference antenna) to 30 dB. The achieved gain is about 5.6 dBi at the resonance frequency 5.8 GHz. The envelope correlation coefficient (ECC) is lower than 7 × 10−5 across the operating bandwidth. The simulated results are in good agreement with the experimental ones. The fabricated antenna exhibits very acceptable radiation performances compared to the conventional one. [ABSTRACT FROM AUTHOR]

This paper presents a novel transmissive type L/Ku dual‐band dual‐polarization (DBDP) shared aperture antenna (SAA) with a large frequency ratio. The L‐band antenna employs a balanced‐fed hollow dielectric resonator antenna (DRA), which has broadband and low cross‐polarization; also, it can be used as a radome to protect the Ku‐band array. The Ku‐band uses a 4 × 4 dual‐polarized microstrip antenna array placed inside the hollow DRA and radiates through it. In order to verify the design, a prototype antenna was manufactured and measured. The measured result shows that the SAA covering the frequency bands of 0.95–1.42 GHz and 13.16–13.84 GHz with the reflection coefficient below −10 dB, the isolation between polarizations is better than 40 dB for L‐band and 25 dB for Ku‐band, the measured gain is 4.8 dBi for L‐band and 16.7 dBi for Ku‐band, and the cross‐polarization level for L‐ and Ku‐band is lower than −28 and −20 dB, respectively. [ABSTRACT FROM AUTHOR]

Compact‐size quad‐band (28/45/51/56GHz) microstrip patch antenna is proposed for the fifth generation (5G) mobile handsets. The present paper introduces a new method to reduce the size of a 28‐GHz rhombic patch antenna so as to properly operate at the higher frequency bands (45/51/56GHz) without negative effects on the antenna characteristics at 28 GHz. A novel design is introduced for the quad‐band patch antenna to include complicated radiation mechanisms required for multiple‐band operation. The proposed antenna is constructed as primary and secondary patches which are capacitively coupled and designed to realize impedance matching and to produce appropriate radiation patterns in the four frequency bands. Numerical and experimental investigations are achieved to assess the performance of the proposed antenna including the return loss, radiation patterns, and efficiency. It is shown that the simulation results agree with the experimental measurements and both show good performance. The bandwidths achieved around 28, 45, 51, and 56GHz are about 0.6, 2.0, 1.8, and 1.3GHz, respectively. [ABSTRACT FROM AUTHOR]

A limitation of the traditional periodic leaky‐wave antennas (P‐LWAs) is the existence of the open‐stopband (OSB) with the antenna gain greatly reduced at broadside. In this paper, a novel periodic microstrip LWA with highly stable gain is proposed and the OSB is eliminated, realizing continual backward‐to‐forward beam scanning. The unit cell of the proposed antenna consists of a transversal slot, a narrow transversal slot and two intersecting oblique slots, as well as a metallic via. By adding a narrow transversal slot and adjusting the inclination of the oblique slots, the antenna gain keeps stable while it is operating. A prototype is proposed and analyzed, achieving continual backward‐to‐forward main‐beam scanning from 8 to 10.2 GHz. The main‐beam scans from −35° to +30° with the maximum gain of 11.36 dBi, and the antenna gain of 11.05 dBi is obtained at broadside at 9.3 GHz with no significant degradation. The variation value of the gain is less than 0.66 dB while the main‐beam is scanning from −28° to +15° near the broadside, indicating that the antenna gain is highly stable. [ABSTRACT FROM AUTHOR]

This paper shows a technique to enhance the radiation gain and efficiency of metamaterial (MTM) inspired planar antenna using substrate integrated waveguide (SIW) technology for sub‐6 GHz wireless communication systems. The antenna consists of MTM unit‐cells comprising series interdigital‐capacitor and short‐circuited spiral stub. The proposed antenna behaves like a leaky wave antenna. In the transmission mode the input signal propagating along the antenna structure and leaks energy. The performance of the antenna is shown to enhance by embedding a column of metallic vias between the MTM unit‐cells. This technique has no impact on the size of the antenna. The antenna was constructed on a standard FR4 dielectric substate. It had dimensions of 23.2×6.4×0.8 mm3 and had a wide operational frequency range 1.8 GHz from 3.0–4.8 GHz. After applying SIW the average gain and efficiency of the antenna were 5.8 dBi and 78%, respectively, which is an improvement of 2 dBi and 21% across 3–4.8 GHz. [ABSTRACT FROM AUTHOR]

This paper presents three configurations of broadband differentially fed microstrip antenna for GSM1800, 1900 and 2100 MHz. The antennas are designed and fabricated using two different substrates for bottom and upper layer. The three antennas designed and tested have gain of 9.88, 9.66, and 11.14 dBi, respectively, at the center frequency. The proposed antennas also find its implementation in areas where, differential inputs/outputs wireless communication circuits are needed. Later, a differentially driven RF power harvesting system with maximum efficiency of 71%, 67% and 78% for a load of 520 Ω is also designed and developed. [ABSTRACT FROM AUTHOR]

In this paper, an electromagnetic band gap structure with fractal geometry based on Peano curves is proposed to suppression of degenerated modes. The geometry is characterized by the inclusion of air slots into the substrate, under the feed line, of a rectangular microstrip patch antenna. The parameters analyzed are the input impedance using the Smith chart, the reflection coefficient (S11), radiation diagram and the electric field distribution of the propagation modes. The simulated results were compared with the measured results, obtained from manufactured prototypes and show that the proposed structure can be used to attenuate and suppress higher‐order modes. [ABSTRACT FROM AUTHOR]

In this paper, a novel compact microstrip patch antenna with a boresight filtering gain response is proposed. The proposed antenna consists of a radiating patch, a ground plane, two pairs of slots respectively etched on the radiating patch and the ground plane, two shorted vias connecting the radiating patch and the ground plane. The slots on the ground plane not only provide a gain null in the lower transition band, but also introduce a new low‐resistance resonance which is beneficial to widen the impedance bandwidth. The slots on the radiating patch provide another gain null in the upper transition band. The two shorted vias are used to further adjust the reflection coefficient and the gain performance of the antenna. Since no extra circuits are introduced, the proposed antenna is compact. A prototype operating at 3.0 GHz was fabricated and measured. It demonstrates that the proposed antenna has a bandwidth of 3.5% and a gain of 6.0 dBi in a profile of 0.015 λ0. At the same time, a good filtering gain response is realized. [ABSTRACT FROM AUTHOR]

A novel low‐radar cross section (RCS) microstrip antenna with radiation performance and antenna volume maintained is proposed in this paper. Different from other antenna RCS reduction methods, the proposed antenna applies shaping method on frequency selective surface (FSS) ground plate to achieve further RCS reduction. In order to obtain the effect of subtracting square slots, an antenna with normal FSS ground is designed as reference antenna. The modified antenna with slotted FSS ground shows more significant RCS reduction compared with reference antenna in the frequency range 4 to 7.5 GHz, the maximum RCS reduction is 14.62 dBsm at 4.22 GHz. And the gain of the modified antenna is increased about 0.2 dB in contrast with the reference antenna. Besides, the modified and reference antenna are fabricated and measured. It is shown that the simulation and measured results are in good agreement. [ABSTRACT FROM AUTHOR]

In this research paper, a isosceles triangular radiating patch with two triangular coplanar parasitic elements has been used to design a compact circularly polarized (CP) microstrip patch antenna that can be used for (2.320‐2.345 GHz) satellite digital audio radio systems (SDARS), (2.30‐2.39 GHz) wireless broadband (WiBro), LTE 2300 (2.3‐2.4 GHz), and WIMAX (2.50‐2.69 GHz) application band. Corners of the two parasitic element along with a portion of driver patch has been cut and optimize to obtain CP characteristics of the antenna with broadside radiation pattern. A slot is also introduced and optimized on the radiating patch to improve the impedance matching. Frequency band generated by the antenna is (2.09‐2.64 GHz) having impedance bandwidth of (S11 ≤ −10 dB) 550 MHz 23.25% and two 3‐dB axial ratio (AR) bandwidth of 5.1% (2.29‐2.41GHz) and 1.54% (2.58‐2.62 GHz). The size of proposed antenna is 56 × 52 × 3.2 mm3 in which, FR4 material has been used as dielectric substrate and thin copper plate as radiating patch and ground. Before physical fabrication, HFSS ver13 software has been used to design and analyzed the proposed antenna. It has been found that the measured results of fabricated antenna and simulated results are closely matching. [ABSTRACT FROM AUTHOR]

The paper reports the bandwidth enhancement of a microstrip slot antenna for on‐metal RFID applications. Microstrip patch with a single conductive layer as wideband and conformal antenna is investigated. The proposed bandwidth enhancement is based on stepped‐impedance slot resonator integrated with an inset‐fed microstrip patch. Slots of different electrical lengths and impedances are configured to generate their respective and distinct resonances, and are subsequently overlapped to create wideband. Equivalent circuit modeling to characterize the antenna in terms of electrical lengths and impedances with respect to their resonances are investigated and reported. These resonances are optimized to overlap using certain numerical equations and the commercially available 2D/3D EM solvers. The resulting antenna is thereafter stamped on the external coating of the pipeline of an RFID specific application for signal monitoring and pipeline integrity. [ABSTRACT FROM AUTHOR]

One frequently addressed technique for the performance enhancement of radiating elements in the form of microstrip antennas is the utilization of dielectric resonators. A dielectric resonator antenna (DRA) has a conventional structural formation similar to any microstrip patch antenna where, at least, one additional dielectric layer has been placed over the radiating element. In this paper, it is aimed to propose a high performance, easy to prototype, light weight, and low cost DRA in combination with frequency selective surfaces (FSS) for ISM band applications using 3D printing technology. The proposed 3D printed FSS loaded DRA has a measured gain of 5.6 dBi with S11 level less than −10 dB in the operation band between 1.98 and 2.68 GHz. Furthermore, the measured performance of 3D printed antenna is compared with the counterpart alternative antenna designs in the literature for the similar application fields. The novel FSS loaded DRA is not only much smaller than the counterpart antenna designs but also has a moderate gain characteristics which makes the proposed antenna design an optimal RF solution for ISM band wireless communication applications. [ABSTRACT FROM AUTHOR]

A microstrip patch electronically‐steerable parasitic array radiator (ESPAR) with continuous frequency reconfigurability is presented in this paper. Loading varactors are strategically placed on the radiating edge of all antenna elements to achieve a 15% continuous frequency tuning range, from 0.87 to 1.02 GHz. At each operating frequency, this ESPAR is able to scan from −20 to 20° in the H plane. Therefore, this ESPAR is able to provide spectrum diversity in addition to the spatial diversity inherent in a frequency‐fixed ESPAR. The underlying physics and design procedures of this ESPAR are presented. The return losses at different operating frequencies and scan angles, radiation patterns, realized gains, and third‐order input intercept point (IIP3) are also measured. [ABSTRACT FROM AUTHOR]

A high‐gain circularly polarized Fabry‐Perot (FP) antenna with chiral metamaterial (CMM)‐based circular polarizer is presented in this paper. It consists of two cavities. One is a U‐shaped slot microstrip antenna with a partially reflecting surface (PRS), acting as an FP cavity. The other is composed of PRS and CMM plate which act as a circular polarizer. According to the experimental results, within the impedance bandwidth of 0.63 GHz from 8.71 to 9.34 GHz, the axial ratio and reflection coefficient S11 of the antenna are less than 3 and −10 dB, respectively. At 9 GHz, the maximum gains of simulation and measurement are 18.5 and 18.3 dB, respectively. The measurement results are according well with the simulation results. Similar methods can be extended to other bands to design high‐gain circularly polarized antennas. [ABSTRACT FROM AUTHOR]

A practical design of reduction mutual coupling is presented between patch antenna elements by using symmetrical microstrip structures in the paper. The patch antenna design consists of the following: two antenna patches, a rectangular substrate plane, a pair of three orders symmetrical microstrips, and a common ground. By using the proposed scheme, approximately 35 dB mutual coupling reduction is achieved at central frequency of 7.3 GHz while maintaining gain of 2.3 dB and directivity of 5.53dBi. Return loss slightly decreases by 2.91 dB from −23.12 to −20.21 dB. In contrast, it exerts no effects on gain radiation characteristics in a no microstrip setup. Simulation results of this technique are verified validated using experimental measurements. [ABSTRACT FROM AUTHOR]

A wideband antenna is studied in this paper using a multi‐layer metasurface structure and implementing a periodic array for enhancing the gain. The performance of the multilayer antenna is improved by using a sub‐wavelength Fabry‐Perot cavity (FPC). The feeding and main radiation patches of the microstrip antenna are placed separately on two substrates, which are stacked on top of each other without an air‐gap in between. Two other substrates are placed within an optimized distance on top of the microstrip antenna. This structure, which has a double‐sided periodic array configuration, includes a capacitive artificial impedance surface (AIS) on one side, and an inductive partially reflective surface (PRS) on the other side of the substrates. Making use of this configuration increases the gain up to 18 dBi and widens the frequency bandwidth. Moreover, measurement results indicate a frequency range from 10.8 GHz to 15 GHz with an S11 less than −10 dB. [ABSTRACT FROM AUTHOR]

This paper presents a better understanding of the use of finite integration techniques (FIT) and finite element method (FEM) in different types of microstrip antennas in order to determine which numerical method gives relatively more accurate results. Although the theoretical formulation based on Maxwell's equations of both FEM and FIT are approached from different aspects in the literature, there is still a lack of comparison of the same antenna type using different numerical methods employing FEM and FIT. Therefore, in this study, FEM and FIT were applied to two different types of microstrip antennas, and their simulation and experimental results was compared. For the first antenna demonstration, a multilayer structure was chosen to achieve one of the significant parameters. Then, a microstrip antenna with a compact structure was used in the second demonstration. Using these two antennas, the accuracy of FEM and FIT in different structures were compared and all simulated return loss and gain results were verified by the measured results. The experimental demonstrations show that FEM performs better for both types of microstrip antennas while FIT provides an adequate result for two‐layer microstrip antennas. [ABSTRACT FROM AUTHOR]

This paper presents a dual‐band dual‐sense circularly polarized (CP) antenna for S‐ and C‐band applications. A semicircular patch and a circular slot are first designed to achieve wide operation bandwidth in the C‐band with right‐hand CP (RHCP), and then, a curved slot is properly inserted around the circular slot for S‐band realization with left‐hand CP (LHCP). Final antenna prototype has an overall size of 0.32λL × 0.32λL × 0.01λL, where λL is free‐space wavelength at the lowest CP frequency. Experimental results show that good CP characteristics for both RHCP and LHCP can be achieved. The measured −10 dB impedance bandwidth is from 2.2 to 6.5 GHz, equivalent to about 98.8%. Additionally, the measured 3 dB axial‐ratio bandwidths for lower and upper bands are, respectively, 4.9% (2.4‐2.52 GHz) and 40.8% (4.0‐6.05 GHz). [ABSTRACT FROM AUTHOR]

This paper describes the design guidelines for frequency independent 180° phase shifters. The proposed configuration is based on microstrip slot transition technique. The frequency independence feature is due to comparing two quasi‐identical structures and the phase inversion (180°) is related to the chosen inverted orientation of the main line compared to the reference one. Moreover, two different schemes are designed and manufactured and a good simulation to measurement agreement is demonstrated. Thus, interesting results are obtained (more than 10 dB return loss, less than 2.1 dB insertion loss and less than ± 3.6° phase deviation). [ABSTRACT FROM AUTHOR]

In this paper, a slotted circular ultra‐wideband (UWB) microstrip patch antenna is reported. The antenna is designed, simulated, fabricated, and tested experimentally. The antenna operates over a 4.0‐40 GHz (164% fractional bandwidth) range with a return loss of 10 dB and voltage standing wave ratio (VSWR) < 2. The designed monopole antenna is of dimensions 28.1 mm × 17.1 mm with an electrical size of 0.37 λ × 0.23 λ at 4 GHz frequency. The antenna is fabricated on FR‐4 substrate with a dielectric permittivity of 4.4, loss tangent of 0.02, and a thickness of 1.4 mm. The designed antenna exhibits nearly omnidirectional radiation patterns over the entire impedance bandwidth with more than 2.8 dB peak gain for the entire frequency range and 75% of average radiation efficiency. The presented antenna can be used in UWB communications along with C‐band, X‐band, Ku‐band, K‐band, Ka‐band, WLAN, and future wireless applications. [ABSTRACT FROM AUTHOR]

A novel compact dual‐band fractal antenna suitable for radio frequency identification (RFID) and GSM 1800 applications is developed and presented in this paper. This is achieved by adequate combination of three slotted hexagonal fractal rings which resulted in a significantly reduced size structure that can operate in the frequency ranges [0.895‐0.962 GHz] and [1.706‐1.856 GHz] that cover the frequency bands allocated to the intended applications. The proposed antenna has been fabricated and its reflection coefficient measured where a good agreement is observed with the simulated results. [ABSTRACT FROM AUTHOR]

In this paper, a series of compact and miniaturized UWB‐printed antennas with a controllable notch function are proposed. The CPW structure is adopted to feed the proposed antenna, where the overall dimension is as compact as 15 mm × 15 mm × 0.5 mm. From 2.8GHz to 12GHz, the antennas proposed have a superior performance with approximate 2:1 VSWR, except the rejection frequency band. In addition, the main feature of the proposed antennas are their controllable notch frequency, notch amplitude, and notch orders, which are determined by the size of the circular U‐shaped slit, the position of the connecting line, and the number of slits, respectively. Moreover, the measured results are in reasonably good with the simulated results. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a novel dual wideband microstrip bandpass filter is proposed. The designed filter is constructed by two different stub loaded resonators located at the upper and bottom sides of the coupling line. The coupling transmission line is also connected to input and output (IO) ports. The upper resonator creates a wide passband, whereas the bottom resonator is used to create two transmission zeros in the passband. Thus, a wide passband can be divided into dual wide passbands. The bottom resonator is also utilized to improve the insertion and return losses in the passband. The designed filter is fabricated and tested in a very good agreement with the simulated results. The measured fractional bandwidths (FBWs) of the passbands are 44.6% and 24.2% at the center frequencies of 3.4 GHz and 5.51 GHz, respectively. The measured insertion losses in the passbands are 0.51 dB and 1.13 dB. [ABSTRACT FROM AUTHOR]

Abstract: A compact branch‐line hybrid coupler with harmonic suppression based on slow‐wave microstrip lines is presented in this paper. These slow‐wave artificial transmission lines are implemented by simultaneously loading a host line with series inductors and shunt capacitors. By this means, the effective capacitance and inductance of the line are increased and, consequently, the phase velocity and signal wavelength are reduced. This slow‐wave effect, useful for device miniaturization, is applied to reduce the size of the coupler. Particularly, by implementing the reactive elements through capacitive patches and inductive strips, 64% size reduction, as compared to the conventional coupler, is achieved. Moreover, due to the filtering capability of the inductors and capacitors, the first and second harmonic responses of the coupler are completely suppressed. A detailed design methodology based on the schematic of the proposed slow‐wave transmission line is reported. The work includes a simple analysis to justify that two unit cells per transmission line section are necessary to suppress the harmonic bands leaving unaltered the coupler response in the region of interest. The fabricated device is fully planar, does not use vias, and the ground plane is kept unaltered. [ABSTRACT FROM AUTHOR]

Abstract: A novel dual‐band filtering power divider using stepped impedance resonator (SIR) and microstrip defect structure (MDS) is proposed in this paper. The power divider mainly consists of the SIRs, MDS, and couple lines instead of the quarter wavelength transmission lines. The SIR, which comprises two pairs of high and low impedance lines, can provide great flexibility for realizing dual‐band performance. The MDS, which has the bandstop characteristic, is applied to effectively suppress the harmonic of the dual‐band filtering power divider. Exact equations and design procedures are given based on strict theoretical analysis. As verification, a dual‐band filtering power divider with two passbands centred at 2.5 and 6.0 GHz is fabricated and measured. The experimental results show good performance and validate the design concept. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a dual‐notch polarization and beam reconfigurable microstrip antenna. It uses parasitics which incorporate switches to steer its beam away from boresight and dual notches which, again, incorporate switches to reconfigure between linear and circular polarization. The antenna is a low profile microstrip patch antenna which only uses a single feed, allowing it to be compact and simple in terms of its structure. [ABSTRACT FROM AUTHOR]

Abstract: This paper introduces a narrow bandwidth tunable filter. The filter has been tuned electronically by using varactor diodes. A set of mechanically tuning screws have been utilized to overcome the manufacturing tolerance of the filter's resonators. In contrast to most the combline filters, which depend on the cross‐coupling approach to generate the transmission poles, the proposed filter has a pair of transmission zeros located on both sides of the passband, by employing two uncoupled microstrip resonators that have been electronically tuned independently. The proposed filter bandwidth tuning range is 59–88 MHz with 3 dB fractional bandwidth 1.94–2.76 respectively. A detailed demonstration of the suggested tunable filter is introduced based on a mathematical approach. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we present a compact dual linear polarized cavity‐backed patch rectenna for optimized wireless RF power transfer with DC power management network. The proposed rectenna is composed of a minimized patch radiator with a backed cavity, the feeding network and a rectifying circuit with DC power management network. The minimized patch radiator with the backed cavity reduces the physical size and enhances the bandwidth. The feeding network is designed to receive all kinds of polarized waves. The rectifying circuit converts received RF energy to DC energy and effectively combines DC energy from each polarization port by DC power management network. The DC power management network also properly operates a load with certain constant voltage. The proposed rectenna is simulated and measured to verify the performance. Each antenna shows about 5.3 dBi peak gain and each rectifying circuit shows about 50% RF to DC conversion efficiency at 0 dBm input power. Due to dual linear polarization, it is observed that received output efficiency is larger than 46% regardless of incident polarization angle. [ABSTRACT FROM AUTHOR]

In this study, a novel inset-fed slotted modified T-shape microstrip patch antenna with DGS is presented. This paper is a demonstration of Differential Algorithm (DE), which is used to optimize the various design parameters of slotted patch antenna in accordance with diverse necessities and scenarios, and also lowers the computation complexity of antenna. The proposed antenna design resonates in two different frequency bands, viz 11.13-11.82 and 15.77-16.89 GHz with their respective bandwidths of 690 and 1120 MHz resonating at 11.47 GHz and 16.27 GHz, respectively. These frequency bands have their application in the field of satellite broadcasting, aeronautical military systems, and radio astronomy corresponding to X and Ku band. The designed antenna has an overall small size of 20 × 11 mm2. The simulated and measured results for the proposed antenna with DE are presented and discussed further. [ABSTRACT FROM AUTHOR]

An ameliorated ultrawide band (UWB) and high-gain microstrip antenna based on planar metamaterial is presented and discussed in this paper. The proposed antenna with a compact size of 32 × 28 × 0.794 mm3 has mesh-shaped patch and patterned ground plane with crossed strip gaps. By means of novel planar metamaterial structure, impedance bandwidth and gain own a significant improvement. The simulations show that the antenna has a super-wide band (less than −10 dB), from 3.06 GHz to 36.4 GHz, covering the entire UWB frequency band (from 3.1 GHz to 10.6 GHz) set by FCC. Within the operating band of concern, the antenna gain can reach as high as 8.02 dB. Due to the surface wave coming from the patterned patch and ground plane, the antenna presents end-fire directional radiation in the higher frequency region. To validate the simulation results, a prototype is fabricated and measured. And the measured results are in good agreement with the simulation results. It is obvious that advantages mentioned above will enable the proposed antenna to be well applied in the short-range wireless communication system. [ABSTRACT FROM AUTHOR]

This paper presents a directive quasi-Yagi antenna designed to ISM band application at 2.45 GHz. The directors application was analyzed, compared and the better performance antenna was manufactured. The obtained measured results presented an agreement with the performed simulations 1% error and bandwidth 27.39%, from 2.3 GHz to 3.03 GHz. [ABSTRACT FROM AUTHOR]

The functionality of a dual-band frequency-reconfigurable antenna based on a microstrip patch is extended toward independent tuning of its two operational bands. The antenna has distinct monopolar and broadside radiation patterns at its lower and upper bands, respectively, and a previous realization only allowed simultaneous tuning of the two bands. In this paper, a more sophisticated bias scheme with two DC bias voltages and four varactors is introduced to extend the principle toward independent control of the resonance frequencies of the two bands. An antenna prototype has been designed, fabricated, and validated with experiments. The results demonstrate that the antenna achieves independent relative tuning ranges of about 11% at both frequency bands. [ABSTRACT FROM AUTHOR]

The theory of characteristic modes (TCM) for PEC bodies is showing great promise and application in the analysis, design, and placement of antennas. Its use for input impedance estimation, however, is still largely dependent on the idealized delta-gap model. Because TCM depends on all conductors, even feed structures, care must be taken for certain classes of antennas if estimating input impedance; probe-fed microstrip patch antennas (MSAs) are one example. In this paper, two different coaxial probe feed models are developed to estimate the input impedance of thin, arbitrarily shaped, air-dielectric MSAs using TCM. Their accuracy is compared with experimental results for a case study of an L-shaped MSA. Results show the importance of including all metal structures, including feeds, in TCM analyses. [ABSTRACT FROM AUTHOR]