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This article presents a novel compact design of an annular ring microstrip antenna (ARMSA), which has two stacked annular rings and is fabricated on a FR4 substrate for radar and satellite applications. The presence of different kinds of slots made the design of the recommended antenna very unique for Ku band applications. This novel compact structure of the antenna provided enhanced bandwidth and high gain. The suggested antenna works in Ku band and has 2.70 GHz bandwidth and 8.42 dB gain, which makes it suitable for satellite applications. The quality parameters of the proposed annular ring microstrip antenna have been compared with other existing annular ring microstrip antennas, which shows its efficient performance. [ABSTRACT FROM AUTHOR]

Antennas with complex radiation characteristics can enhance the adaptability of radiofrequency systems in complex electromagnetic environments. However, The realization of complex targets is extremely challenging for conventional antenna design methods. It is difficult to find a suitable initial topology of the antenna with complex radiation characteristics. Therefore, in this paper, topology optimization is used to explore the initial structure with complex radiation properties. A two‐dimensional lossy thin layer model based on the transitional boundary condition is constructed, and target field functions for complex radiation are proposed. To verify the effectiveness of the algorithm, a high gain antenna with 10.2 dBi is realized, which has the highest aperture efficiency compared with the literature in similar directions. Then, for more complex targets, the radiation patterns of arbitrary direction null, arbitrary direction beam, and equal‐amplitude dual beam are realized, respectively. The topology optimization algorithm provides a new approach for the design of complex multitarget antennas. [ABSTRACT FROM AUTHOR]

This paper presents a simple, low-profile rectangular microstrip patch antenna operating in the V-band for WiGig applications. The initial design involves a rectangular microstrip patch antenna modified by inserting a small circular slot into the radiating patch to adjust the resonance at 60 GHz and enhance its reflection coefficient performance. To support the proposed structure, a fully grounded Rogers RT/Duroid-5880 dielectric substrate, having a dielectric constant of 2.2, a loss tangent of 0.0009, and a thickness of 0.12 mm, is employed. The final design measuring 4 x 7.4 x 0.12 mm³ attains a stable gain above 10.33 dBi over the operational band with a maximum realized gain of 10.61 dBi and a minimum S11 value of – 60 dB at the center frequency. Likewise, the proposed antenna achieves a minimum VSWR of 1.026. In addition, the antenna realizes an impedance bandwidth of 2.22 GHz extending from 58.809 GHz to 61.029 GHz and a radiation efficiency above 89%. The CST is utilized for antenna design, simulations, and optimizations, while HFSS validates the simulation results. The simulation outcomes from both software simulators indicate a good level of agreement. Keywords: V-Band, Compact antenna, High gain antenna, Circular slots, WiGig ap [ABSTRACT FROM AUTHOR]

In the realm of mmWave communication and connectivity, integrating chips and antennas into a cohesive system is paramount. Given this, planar antenna arrays have become indispensable. In this article, we introduce a novel antenna array tailored for mmWave applications, characterized by its high directivity. Distinctively, this new array employs a flat-panel radiator, ensuring an augmented gain without necessitating additional superstrate layers. To validate its potency, a 4 × 4 flat-panel array with dimensions of 3.74 λ0 × 3.74 λ0 × 0.106 λ0 at 28 GHz including a ground plane was designed and tested for n257 band. The standalone array element exhibited a bandwidth of 20.6%, centered at 28.5 GHz. Furthermore, a 1 × 16 mmWave feed network was designed and amalgamated with the array elements to assess the comprehensive antenna performance. The measured peak gain of 21.3 dBi at 28.5 GHz was observed with the measured half power beamwidth of 15° while the gain variation within the operation band was less than 3 dB. [ABSTRACT FROM AUTHOR]

This letter presents a design of a high gain uniplanar end‐fire electrically small antenna. The design starts from an equivalent antenna of an antenna array with two half‐wavelength dipoles, which consists of two linear strips and produces the end‐fire unidirectional radiation. Two U‐shaped strips are utilized to replace the linear strips, which makes the antenna compact. In addition, a spilt‐ring resonator is loaded to make the realized gain of the electrically small antenna increase by ~2 dB. An antenna prototype is fabricated and measured. The measurements reveal that the proposed antenna has a peak realized gain of 6.02 dBi and a front‐to‐back ratio of 12.71 dB at its resonance frequency of 747.8 MHz. Its size is only 0.254 λ0 × 0.184 λ0 × 0.0037 λ0, and ka = 0.984. The measured realized gain exceeds both the Harrington and Kildal–Best ka‐based upper limits. [ABSTRACT FROM AUTHOR]

This paper presents a waveguide–slot antenna to generate a radiation beam with high gain fed by a low-loss feeding network at 110 GHz. The proposed antenna consists of a compact eight-way power divider and a waveguide–slot array. The eight-way power divider provides equal-amplitude and alternative-phase excitation for the slot array, and each of them supports two waveguides. The integral structure is implemented by two layers with a channeled substratum and a slotted superstratum. To verify the proposed slot array, the designed array is fabricated with computer numerical control (CNC) milling and measured. The measured peak gain of the designed antenna is 32 dBi at 110 GHz. The proposed antenna with a simple structure provides a promising solution to develop high gain antenna in upper millimeter-wave and sub-terahertz (THz) applications. [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]

This paper proposes an effective planar mmWave switched beamforming antenna array with low complexity and wide beam coverage. The proposed structure is configured using multiple linearly polarized self-beam-tilting-antenna (SBTA) elements, eliminating the requirement of a phase-adjustable block for beamforming. Each SBTA element can generate different main beam directions by itself without using complicated feed networks. Moreover, unlike typical Butler matrix-based beamforming arrays, the proposed SBTA array does not require passive hybrid couplers to adjust the phases for beamforming operations. Accordingly, the proposed feed network-less antenna avoids circuit complexity, feed network insertion losses, or increases in size and fabrication costs, rendering it suitable for mmWave compact antenna applications. To verify the proposed concept and beamforming performance, a 1 × 4 SBTA array was fabricated at 28 GHz using a conventional printed circuit board (PCB) process. The size of the fabricated antenna (excluding test connectors) was 1.12 λ 0 × 1.68 λ 0 × 0.08 λ 0 (λ 0 for free-space wavelength), and the measured 10-dB impedance bandwidth was approximately 5.9 %. Furthermore, the measured main beam switching directions were found at −34°, −52°, +51°, and +38° with measured gains of 6.7, 6.1, 5.9, and 6.6 dBi, respectively, at 28 GHz. [ABSTRACT FROM AUTHOR]

This article proposes a high‐gain quasi‐Yagi antenna using nested metaresonator structures with a systematic design approach. The nested metaresonators are used as a director element instead of conventional strip directors. The gain enhancement of the proposed antenna is based on strong electromagnetic coupling between the driver and metaresonator director elements. The proposed antenna has a gain of 7.6–9 dBi with a bandwidth of 8.6% between 2.43 and 2.65 GHz (S11≤−10 ${S}_{11}\le -10$ dB). It achieves a maximum gain increase of 4 dBi compared to the conventional quasi‐Yagi antenna and 2 dBi compared to the four‐director quasi‐Yagi antenna. The proposed antenna can be used for wireless communication applications that require high gain. [ABSTRACT FROM AUTHOR]

A high gain antenna with Mu-near-zero metasurface (MNZ-MS) is introduced in this work. The proposed antenna can be utilized for future 5G applications. The patch antenna is designed on the upper face of the square substrate with a ground plane at the bottom face. To improve the antenna gain, a layer of MNZ-MS unit cells is placed above the antenna substrate with 0.48 λ 0 air space between the two layers, where λ 0 is the wavelength in free space at the resonance frequency of 26.3 GHz. The MNZ-MS layer consists of four double-sided split square resonators. The overall thickness of the proposed antenna is 0.66 λ 0. To approve the execution of the proposed antenna, a prototype model is manufactured and tested. The outcomes fulfill a reflection coefficient lower than −10 dB over the frequency spectrum of 26–28 GHz. A gain improvement better than 5 dB is obtained compared to the gain of the reference patch at the center frequency of 26.3 GHz. [ABSTRACT FROM AUTHOR]

In this article, a single-layer frequency selective surface (FSS)-loaded compact coplanar waveguide (CPW)-fed antenna is proposed for very high-gain and ultra-wideband applications. At the initial stage, a geometrically simple ultra-wideband (UWB) antenna is designed which contains CPW feed lines and a multi-stub-loaded hexagonal patch. The various stubs are inserted to improve the bandwidth of the radiator. The antenna operates at 5–17 GHz and offers 6.5 dBi peak gain. Subsequently, the proposed FSS structure is designed and loaded beneath the proposed UWB antenna to improve bandwidth and enhance gain. The antenna loaded with FSS operates at an ultra-wideband of 3–18 GHz and offers a peak gain of 10.5 dBi. The FSS layer contains 5 × 5 unit cells with a total dimension of 50 mm × 50 mm. The gap between the FSS layer and UWB antenna is 9 mm, which is fixed to obtain maximum gain. The proposed UWB antenna and its results are compared with the fabricated prototype to verify the results. Moreover, the performance parameters such as bandwidth, gain, operational frequency, and the number of FSS layers used in the proposed antenna are compared with existing literature to show the significance of the proposed work. Overall, the proposed antenna is easy to fabricate and has a low profile and simple geometry with a compact size while offering a very wide bandwidth and high gain. Due to all of its performance properties, the proposed antenna system is a strong candidate for upcoming wideband and high-gain applications. [ABSTRACT FROM AUTHOR]

Studying the geometry of electromagnetic band gap (EBG) structures in 1 and 3 dimensions is useful for achieving effective directional radiation, high gain, and side-lobe attenuation of antennae. This paper presents an EBG antenna, whose radiating source is a rectangular notched patch, which can be used for applications around 20 GHz. Two conventional woodpile dielectric structures with a triangular lattice are presented in a comparative study to extract the best physical and electromagnetic performance in terms of directivity, bandwidth, and gain; these are the square and the cylindrical rods. These two structures' electromagnetic and geometrical limits allow the design of a 3D EBG structure called an icosahedral structure. The proposed antenna is composed of different ceramic substrates (the Arlon AR 450, (h = 0.48 mm, ɛr = 4.5, El Tand = 0.0035) on which the radiating element is placed, the Rogers TMM 13i, (ɛr = 12.85, El Tand = 0.0019) for the 3D icosahedral structure; and the Taconic TLY-5A, (ɛr = 2.17, El Tand = 0.0009) for the 1D lateral walls). With a substrate-plated radiation source coupled with a 3D icosahedral structure and surrounded by a vertically mounted 1D structure, a directivity of 19 dBi was obtained with a realized gain of 17.7 dB and an optimal coupling (antenna–EBG material) at 19.8 GHz. These results are encouraging given the antenna size of 33.41 × 27.87 × 37.36 mm3. [ABSTRACT FROM AUTHOR]

This paper presents the design of wideband and high gainFrequency Selective Surface (FSS) loaded antenna for ultra-wideband (UWB) wireless applications requiring high-gain. The antenna consists of a monopole and an FSS reflector. Initially, a conventional rectangular monopole antenna is modified using slot and stub to achieve wide operational bandwidth and size reduction. This modified antenna shows 50% miniaturization compared to a primary rectangular monopole, having a wide impedance bandwidth of 3.6-11.8 GHz. Afterward, an FSS is constructed by the combination of circular and square ring structures. The FSS array consisting of 8×8-unit cells are integrated with the antenna as a reflector to enhance the performance of the proposed miniaturized UWB antenna. The loading of FSS results in an improvement of at least 4 dBi gain in the entire operational bandwidth. Moreover, the antenna's bandwidth is also increased at the lower frequency band due to the presence of the FSS. A prototype of the antenna is fabricated and tested to verify the simulation results. The simulation and measurement results show that the antenna offers a wideband -10 dB impedance bandwidth ranging from 2.55-13GHz with a stable peak gain of 8.6 dBi and retains the radiation pattern stability. [ABSTRACT FROM AUTHOR]

This paper presents the design and analysis of antipodal Vivaldi antennas (AVAs) for breast cancer detection. In order to enhance the antenna gain, different techniques such as using the uniform and non-uniform corrugation, expanding the dielectric substrate and adding the parasitic patch are applied to original AVA. The design procedure of two developed AVA structures i.e., AVA with non-uniform corrugation and AVA with parasitic patch are presented. The proposed AVAs are designed on inexpensive FR4 substrate. The AVA with non-uniform corrugation has compact dimension of 50×50mm2 or 0.28λL×0.28λL, where λL is wavelength of the lowest operating frequency. The antenna can operate within the frequency range from1.63GHz to over 8 GHz. For the AVA with parasitic patch and uniformcorrugation, the overall size of antenna is 50×86mm2 or 0.24λL×0.41λL. It can operate within the frequency range from 1.4GHz to over 8 GHz. The maximumgain forAVA with non-uniform corrugation and AVA with parasitic patch and uniform corrugation are 9.03 and 11.31 dBi, respectively. The corrugation profile and parasitic patch of the proposed antenna are optimized to achieve the desired properties for breast cancer detection. In addition, the proposed AVAs are measured with breast phantom to detect cancerous cell inside the breast and the performance in detecting cancerous cell are discussed. Themeasured result can confirmthat the proposedAVAs can detect unwanted cell inside the breast while maintaining the compact size, simple structure and low complexity in design. [ABSTRACT FROM AUTHOR]

A generic field analysis technique for a liquid antenna along with a novel high‐gain structure of water antenna is presented in this article. The antenna design has liquid material as a conducting radiator contained within a tube, placed on a grounded dielectric substrate. This monopole antenna is fed by a coaxial feed, having the radiating pin inside liquid. The antenna is divided into different regions, and boundary conditions are applied to obtain the resultant field equation. The proposed technique is validated using simulated and measured results, with an existing design with seawater as radiator, and helps to predict the E‐field of water antenna in advance to be used as a reconfigurable antenna. Parametric analysis is done to achieve the best antenna design, and a high‐gain water antenna with gain value of 23.53dB, resonating at 2.9GHz having a bandwidth of 1.08GHz is proposed and fabricated. The high gain is achieved by placing a superstrate on top of the structure at a cavity height of 11mm. This seawater monopole antenna delivers broad bandwidth with high gain and is an attractive option to be used as a reconfigurable antenna. [ABSTRACT FROM AUTHOR]

Integrated lens antennas are widely used in high gain and beam steering applications at millimeter-wave frequencies. The ILA has often large height and suffers from significant scan loss. In this article, we demonstrate a low-profile, efficient, and scanloss-reduced integrated metal-lens antenna (IMLA). An IMLA is a combination of a dielectric lens and metal–plate lens. A 16- $\lambda _{0}$ diameter IMLA is designed using the HDPE and 58 stainless steel plates to achieve the $f/d$ of 0.69. The simulated aperture and radiation efficiency of the IMLA are 73% and 92%, respectively. At 76 GHz, the simulated and measured realized gains of the fabricated IMLA are 31.24 and 31 dBi, respectively. The IMLA is designed to steer the main beam to ±30°. The scan loss is reduced by tilting the radiation pattern of the feeds at offset positions along the focal plane. The radiation pattern of the square waveguide feed is tilted using asymmetrical dielectric pins. The asymmetrical dielectric pins reduce the simulated gain scan loss of the IMLA by more than 1.5 dB at 30° steering angle. The simulation results show that the inclination of the feed radiation pattern helps limit the scan loss of the IMLA to 4.1 and 4.3 dB in the H- and E-planes for 30° steering angle, respectively. The measured scan loss of the manufactured IMLA is 3.8 and 6.2 dB in the H- and E-plane, respectively. [ABSTRACT FROM AUTHOR]

By introducing a V‐shaped air slot in antenna substrate, the peak gain can be improved significantly for traditional Vivaldi antennas without size enlargement and additional components. The air slot is conformal to the radiating conductors of the target Vivaldi antenna, and can force the electromagnetic wave to propagate within the central dielectric part between the antenna's opening slot, by decreasing the effective dielectric permittivity of the regions along the radiating conductors. As a result, the wave distributes more evenly within the radiating aperture comparing with the traditional designs, especially at high frequencies, hence the peak gain can be enhanced. In addition, the removal of antenna back substrate is evaluated on radiation characteristics, which can further improve antenna gain and front‐to‐back ratio. For verification, three antennas within operating frequency band from 0.8 to 6.0 GHz are designed with the same dimensions (220 mm × 256 mm) but different configurations. The simulations show that the peak gain increases from 2.0 to 12.0 dBi gradually for the air slot loaded antenna. The gain increment is about 4–6 dB from 4.0 to 6.0 GHz comparing with the one without air slot. A sample antenna with both air slot and removal of back substrate is fabricated and measured. The measured reflection is better than −10 dB from 0.8 to 6.0 GHz, and the measured gains at (0°,0°) direction are from 2.3 to 11.0 dBi. The antenna patterns at high‐band shows that the main lobe in E‐Plane is narrowed successfully after introducing the V‐shaped air slot. The experimental data agree well with the prediction with in‐band radiation efficiency better than 65%. [ABSTRACT FROM AUTHOR]

A multi‐state high gain antenna based on metasurface is proposed. The antenna is composed of two stacking layers and a ground plane. The metasurface is constituted by two layers with the same size. And both of the two layers contain a copper patch array which is formed by 4 × 4 square copper cells uniformly distributed along x and y directions. The metasurface antenna is excited by the aperture coupled structure. The structure is consists of an anomaly microstrip line and a narrow slot etched in the ground plane. Genetic algorithm (GA) is adopted to optimize all the parameters and obtain the best performance of the metasurface antenna. By appropriately choosing the dimensions of the antenna, the proposed antenna can be achieved with the impedance bandwidth (RL≥10 dB) of about 340 MHz (7.8% at 4.36 GHz), 180 MHz (3.6% at 5.02 GHz), and 2800 MHz (41.1% at 6.81 GHz). The peak gain of the proposed antenna is 10.1dBi, 6.9 dBi, and 10.5dBi at 4.26 GHz, 5 GHz, and 7 GHz. In addition, the proposed metasurface antenna can work in multistate, which makes it an excellent candidate for practical applications. [ABSTRACT FROM AUTHOR]

In this article, a narrow and a wide band high gain antenna with improved front to back ratio using highly reflecting surface are proposed. A highly reflecting compact ultrathin metasurface (MS) of thickness 0.0134 λ with >90% reflection band of 1.42 GHz from 4.55 to 5.97 GHz is designed. The open air field Fabry–Perot cavity resonator antenna is designed by placing this MS over a microstrip patch antenna radiator first and next on standard wide band C‐band wave guide port radiator at an optimum height to get narrow and wide enhanced gain band width, respectively. The proposed antennas are fabricated and measured experimentally. A low profile narrow band FPC antenna with measured broad side gain enhancement of 8.54 dB having maximum measured gain of 16.5 dBi at 5.3 GHz is designed first. Next, a wide band FPC antenna having broad side measured enhanced gain band width of >1 GHz from 4.75 GHz to about 6.00 GHz with maximum gain enhancement of 8.32 dB with maximum measured gain of 17.85 dBi at 5.30 GHz is observed. A wide improved front to back ratio (FBR) band of 1 GHz with maximum FBR of 39.5 dB at 5.30 GHz is presented. This antenna can be used for 5G long range services. [ABSTRACT FROM AUTHOR]

Abstract: This article presents electrically steerable passive array radiator inspired high gain, mechanical beam steering configuration, operating in the wide frequency band with frequency dependent radiation characteristics. Monopole antenna in combination with twelve parasitic elements is fed through impedance matching network and offered impedance bandwidth of 32.0% and approximate gain of 9.0 dBi. [ABSTRACT FROM AUTHOR]

In this paper, a compact wideband directive metasurface (MS)-based antenna is proposed. A pair of edge-fed slots, assisted by a fictitious short, is used to excite the MS layer which is made up of a periodic arrangement of rectangular loop-based unit cells along both the x - and y -directions. The proposed MS-based slot antenna is compact and provides good matching over the entire bandwidth with a broadside radiation pattern. A metallic cavity and an artificial magnetic conductor-based cavity are integrated on the MS-based antenna to reduce its backward radiation. Finally, a pair of edge-fed slot antennas combined with two layers of MSs having compact ground plane area of 1.04 \lambda 0^{2} ( \lambda 0 is the operating wavelength in free space) is proposed for the improvement of gain, bandwidth, and forward radiation. The overall antenna has a low profile of 0.05 \lambda 0 . The proposed configuration shows a 21% measured bandwidth with an average gain of 9.6 dB over its bandwidth. Over its bandwidth, the antenna efficiency is >89%. The design is validated by a full-wave simulation study followed by the experimental verification. [ABSTRACT FROM PUBLISHER]

A wideband antenna has been conceived and realized from a single metallic patch with air as the substrate. The patch has been strategically folded to achieve dual resonances resulting in \textS11 \leq 10\,\text{dB} over a wide matching bandwidth. Basic design concept has been discussed and experimentally verified. As much as 26% bandwidth covering almost the full X-band with about 9.6 dBi peak gain has been experimentally demonstrated from a 20.3\,\textmm \times 13\,\textmm patch folded to realize 13\,\textmm \times 13\,\textmm footprint. [ABSTRACT FROM PUBLISHER]

A wideband high-gain high-efficiency hybrid integrated plate array antenna for inter-satellite links is presented in this paper. This antenna consists of microstrip patches, substrate integrated waveguide (SIW) and waveguide power dividers. A novel feeding structure is proposed to excite the microstrip sub-array with a wideband characteristic. The radiation efficiency of SIW arrays with different sizes is compared by experiment. The hybrid SIW-waveguide feeding topology is optimized to realize high efficiency, low cost and compact configuration at the same time. The array antenna is fabricated through standard multi-layer PCB process and milling technology. Measured results demonstrate about 14.6% of reflection coefficient bandwidth (\vert S11\vert < - 10 dB) in the frequency band of 57–66 GHz. The gain fluctuates less than 3 dB within the same band. The 1 dB gain bandwidth is 8.1% within the frequency band of 59–64 GHz. The maximum gain is 39.2 dBi at 59 GHz with the efficiency of 41%. [ABSTRACT FROM PUBLISHER]

A fed patch antenna is printed on a dielectric substrate (substrate 1) and a parasitic dielectric substrate (substrate 2) is located above the patch. Parasitic substrate 2 has M\times(2N-1) strip loops on its bottom layer. The strip loops are square and specified by a fixed outer side length of sout and inner side lengths sm({m}=1,2,\ldots,{M}). When all the inner side lengths are equal, a high gain beam is formed in the direction normal to substrate 2. This normal beam is tilted by changing the phase distribution of the electric field over a horizontal plane just above substrate 2. It is found that gradating the strip widths of the loops contributes to changing the phase distribution, forming a high-gain tilted beam. A system of M\times(2N-1)=9\times 9 shows an experimental maximum gain of 16.4 dBi for a 33^\circ beam tilt. The frequency responses for the radiation pattern, beam direction, and VSWR for this high-gain antenna are also discussed. [ABSTRACT FROM PUBLISHER]

In this letter, we report the design, fabrication, and measurement of a metamaterial-based Fabry-Perot (F-P) resonator antenna. The F-P resonator antenna is constructed of a fishnet superstrate and a printed patch antenna based on a mushroom-like electromagnetic bandgap substrate. Simulated and measured results show that the proposed F-P resonator antenna achieves an ultra-low profile as well as a high-gain enhancement. The thickness of the metamaterial-based F-P resonator is only λ/125. Compared to the traditional superstrate patch antenna, the forward gain of the new metamaterial F-P resonator antenna is enhanced and the back radiation is suppressed effectively. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2620-2623, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27155 [ABSTRACT FROM AUTHOR]

A new design approach for a mmWave high gain planar antenna is presented. The proposed method can increase antenna directivity with a minimally enlarged radiation patch while the operation frequency is still matched at a higher target frequency. The fundamental structure of the proposed antenna is configured by a H-shaped and slot-loaded patch with a shorting pin symmetrically located across a signal excitation port. Further, to match the operation frequency with the frequency for the highest achievable gain, a vertically stacked matching conductor was inserted along the signal feed path between the radiation patch and the ground layer. The proposed single antenna showed the simulated directivity of 9.46 dBi while the conventional patch with a same dielectric had 8.07 dBi. To verify practical performance, a 2 × 2 array antenna was fabricated at 28 GHz and showed the measured gain of 12.5 dBi including the array feed loss. [ABSTRACT FROM AUTHOR]

A new single-feed technique for high gain operation of the circularly polarized cross-slot antenna backed by a ground reflector is presented. The antenna, which has a size of one wavelength, exhibits a gain of 11 dBi over a 3dB axial ratio bandwidth of 5%. Simulations are performed using an EM simulator IE3D and agree well with experimental results. [ABSTRACT FROM AUTHOR]