Radiation Beamwidth Research Articles

Compact reconfigurable antenna with pattern diversity for K band applications

SummaryA novel pattern reconfigurable antenna is proposed in this letter. The overall dimension of the antenna is 11 × 11 × 0.787 mm. The proposed antenna is fabricated on Rogers RO4003C substrate. The antenna has two meandered monopoles and two straight monopoles. Two PIN diodes are connected between meandered monopoles and feed. The proposed design has three states of switching, that is, ON‐ON, ON‐OFF, and OFF‐ON. The antenna radiates from 18.5 to 26.25 GHz band with more than 5 GHz (−10 dB) bandwidth for all states. The proposed geometry exhibits 270° radiation beamwidth with 45° and 135° directions for ON‐OFF and OFF‐ON state, respectively.

A Reconfigurable Switched-Beam System with Single/Dual-Lobe and Wide-Beam Radiation Patterns

A Reconfigurable Switched-Beam System with Single/Dual-Lobe and Wide-Beam Radiation Patterns

A Multi-Mode Pattern Diverse Microstrip Patch Antenna Having a Constant Gain in the Elevation Plane

This study investigates a multi-mode pattern diverse microstrip patch antenna operating at 2.45 GHz. The study aims to have a flat top gain covering more than 900 in the elevation plane to provide equal service quality to everyone in the region of interest. In order to achieve such a crucial goal, the cavity model approach for the rectangular patches is employed. TM01 and TM02 modes are selected for the design since their corresponding radiation patterns are suitable for scanning a wide range. The superposition of boreside and conical (monopole-like) beams form a wide beam radiation pattern in elevation. Coupling between different modes is reduced by placing two radiators perpendicular to each other. In addition, the design aims to reduce both initial dimensions of the antenna by using fractalization, slotting, and perpendicular positioning techniques. These techniques reduce the original dimension of the design to less than its 60%. The simulation and experimental results reveal many similarities regarding the scattering parameters, radiation patterns, and gain. The scattering parameters, |S11| and |S22| at the operating frequency, are less than -10 dB, and the wide beam radiation pattern (more than 900) is obtained in the elevation plane.

A Half-Biconical Antenna With Enhanced Unidirectional Radiation Using Irregular Dielectric Lens

Aimed to resolve the beam splitting in high frequency, an improved half-biconical antenna using an irregular dielectric lens is designed. Based on the conventional shark antenna, the metal reflector on the back is removed, and an optimized irregular dielectric lens is loaded in front of the antenna to form a plane wave.In this way, the radiation beamwidth becomes more concentrated and the boresight gain in the middle and high-frequency bands is improved. To validate the design, a prototype is fabricated and tested. Measured results show that the impedance bandwidth reaches 1.02–31GHz for VSWR<2. In the impedance bandwidth, stable directional radiation is achieved in both E- and H-plane.

Filter-Bank-Enabled Leaky-Wave Antenna Array Technique for Full-Band-Locked Radar System in Stitched Frequency-Space Domain

Inspired by the filter-bank (FB) concept that is normally used for multi-rate signal processing, an FB-enabled array technique of leaky-wave antennas (LWAs) is proposed and studied for creating full-band-locked frequency-scanning radar (FSR) systems in a stitched frequency-space domain. This is mainly for addressing the coupling dilemma between the range and angle resolutions, which is historically and naturally inherited from a conventional FSR. Firstly, the typical frequency-modulated continuous-wave system architecture is selected to exemplify and recall the characteristics of a conventional FSR with emphasis on its resolution coupling. Then, a radar solution featuring a stitched frequency-space domain and depending on an FB-enabled array of LWA channels is introduced for realizing the desired resolution decoupling. With the radar equation, FB-related conditions for obtaining the critical “frequency-space stitching” are analytically derived and converted into relevant design specifications of an LWA array, including engineered beam-scanning functions, beam-crossovers, and phase alignments. To facilitate the practical implementation of such a front-end array technique, a detailed and generalized design flow is developed. Finally, for a simple proof of concept, an FB-enabled two-channel LWA array is modeled, fabricated, and measured. Simulated and measured results are in reasonable agreement; both demonstrate the desired “frequency-space stitching” behavior, i.e., enhanced spectrum bandwidth and widened radiation beamwidth. The proposed array solution may be potentially deployed for FSR systems with a full-band-locked beam illumination and a decoupled range-angle resolution, which may present a highly competing scheme against the phased array radar techniques.

A high‐performance dual‐polarized corrugated horn for a compact antenna test range system

AbstractA high‐performance dual‐polarized horn antenna for a 5G millimeter wave compact antenna test range system (CATR) is proposed in this article. The feed antenna is mainly composed of a double‐ridged waveguide junction orthomode transducer (OMT), mode converter, and corrugated horn antenna. Among them, the OMT is the key device for the feed antenna to achieve dual polarization characteristics, and adopts a modular design method to apply the multi‐section impedance transformer in the vertical and horizontal polarization channels with good transmission characteristics. The corrugated horn antenna generates a symmetrical radiation pattern mainly in six corrugated slots. The proposed dual‐polarized corrugated horn antenna impedance matching bandwidth (VSWR &lt; 2) is 24–50 GHz. Moreover, the measured gain is 10–12 dBi, and the measured cross‐polarization level is less than −30 dB within the operating frequency range. Meanwhile, the half‐power beamwidth radiation pattern in the whole operating band has a good symmetry and the beamwidth in both E‐ and H‐plane remains stable. As a practical application, the designed antenna is used as the feed of the CATR system. The measured results show that the amplitude distribution in the quiet zone (QZ) is within ±1 dB, the phase distribution is within ±8°, and the cross‐polarization isolation is better than 27 dB. The performance of the QZ is conducive to the use of the CATR system.

A Simple Wide-Angular Scanning Phased Array With Wideband Filtering Response

This article presents a low-profile planar phased array with improved reflection (wideband filtering response) and radiation (wide-angular scan) performance. On one hand, the filtering response with harmonic suppression is integrated into the design of the single-layer array element without extra filtering resonators, such as external filters. As a result, the designed array possesses a reflection bandwidth of 4.6–5.3 GHz and two radiation nulls at either the upper or lower band edge of the reflection curve. On the other hand, inspired by the wide-beam radiation of a circular patch loaded with parasitic monopoles, the proposed array is able to realize its beam scanning coverage of −60°–+60° with low sidelobe levels (SLLs) in its E-plane. The reflection and radiation properties are validated by full-wave simulation and measurement of an eight-element array prototype. The filtering and low-SLL performance benefit for the array to avoid out-of-band interferences and in-band ones from other directions when it scans in a wide-angular area.

Highly Unidirectional Radiation Enhancement Based on a Hybrid Multilayer Dimer.

Dimers made of plasmonic particles support strong field enhancements but suffer from large absorption losses, while low-loss dielectric dimers are limited by relatively weak optical confinement. Hybrid dimers could utilize the advantages of both worlds. Here, we propose a hybrid nanoantenna that contains a dimer of core-dual shell nanoparticles known as the metal–dielectric–metal (MDM) structure. We discovered that the hybrid dimer sustained unidirectional forward scattering, which resulted in a nearly ideal Kerker condition in the frequency close to the resonance peak of the dimer due to enhancing the amplitude of the induced high-order electric multiples in the gap and effectively superimposing them with magnetic ones, which respond to the excitation of the plane wave in the dielectric layer of the dimer. Furthermore, when an electric quantum emitter is coupled to the dimer, our study shows that the optimal hybrid dimer simultaneously possesses high radiation directivity and low-loss features, which illustrates a back-to-front ratio of radiation 53 times higher than that of the pure dielectric dimer and an average radiation efficiency 80% higher than that of the pure metallic dimer. In addition, the unique structures of the hybrid hexamer direct almost decrease 75% of the radiation beamwidth, hence heightening the directivity of the nanoantenna based on a hybrid dimer.

A compact wide beamwidth dual‐polarized antenna for 5G new radio

In this article, a compact wide beamwidth dual-polarized antenna is proposed and experimentally investigated. The operating frequency band of the antenna presented in this article is 3.29–5.28 GHz, covering n77, n78, n79 frequency bands of the 5G new radio (NR) bands. The stable wide beamwidth radiation pattern is obtained by encircling a metal wall around the traditional metal flat floor. Furthermore, the bandwidth of the antenna is improved by using the metal wall with grooves and trapezoidal parasitic elements. With these rectangular grooves, the dimensions of the antenna presented in this article are decreased. The impedance bandwidth of the antenna is 46.4% (|S11| ≤ –10 dB). The isolation between the two ports is higher than 22 dB in 3.29–5.28 GHz. The half-power beamwidths of the H-plane and the E-plane are greater than 110° and 102° in 3.3–5.0 GHz, respectively.

Light-weight wideband antenna array with low sidelobes for SAR applications

PurposeThe purpose of this study is to achieve the low-cost, light-weight and compact antenna array with wide bandwidth and low side lobe levels for synthetic aperture radar (SAR) applications in Ku frequency band.Design/methodology/approachA compact design of a rectangular microstrip patch antenna array using multilayered dielectric structure is presented in Ku-band for advanced broadband SAR systems. In this design, stepped pins are used to connect the microstrip feed lines to the radiating patches.FindingsThe simulation and fabrication results of the multilayered antenna and a 1×16-element linear array of the antenna with Taylor amplitude distribution in the feeding network are presented. The antenna element has a 10-dB impedance bandwidth of more than 26%, and the linear array shows reduction in bandwidth percentage (about 15.4%). Thanks to Taylor amplitude tapering, the side lobe level (SLL) of the array is lower than −24 dB. The maximum measured gains of the antenna element and the linear array are 7 and 19.2 dBi at the center frequency, respectively.Originality/valueIn the communication systems, a high gain narrow beamwidth radiation pattern achieved by an array of multiple antenna elements with optimized spacing is a solution to overcome the path loss, atmospheric loss, polarization loss, etc. Also, wideband characteristics and compact size are desirable in satellite and SAR systems. This paper provides the combination of these features by microstrip structures.

Dual-Band Dual-Mode Patch Antenna With High-Gain and Wide-Beam Radiations in Two Respective Bands

In this article, a novel dual-band dual-mode (DBDM) patch antenna is proposed with flexible radiation coverage and a simple structure. Distinct radiation properties with high-gain in the lower band and wide-beam in the upper band could be attained under a small frequency ratio and a single element. The working principle of the wide-beam radiation is, for the first time, proposed and theoretically analyzed based on the electric current calculation, providing a good insightful understanding of the radiation of the inverse currents. The high-gain radiation in the lower band is realized by introducing the shunt inductive effect while maintaining a negligible influence on the upper band. In terms of realization, a pair of stubs and shorting pins are properly loaded on a square patch to achieve the conditions required in the theoretical analysis. It indicates that the proposed method could be easily achieved with the simple structure of a single layer and a single element. Additionally, further discussion on the size reduction of the patch is provided with good cross-polarization. Two prototypes are finally designed, fabricated, and tested. The simulated and measured results exhibit good agreement with each other, certifying the validity of the proposed method. All these attractive merits, such as flexible coverage with high-gain and wide-beam radiations, simple structure with a single element, small achievable frequency ratio, and low profile, demonstrate that the proposed antenna could be a good potential candidate in the modern wireless systems.

Plasmonic leaky wave antenna based on modulated radius of cylindrical graphene waveguide

In this paper, the concept, analysis, and synthesis of a novel plasmonic leaky wave antenna (LWA) based on the modulated radius of a cylindrical graphene waveguide (CGW) at the terahertz band are presented. Devices based on the planar graphene waveguide (PGW) suffer from high attenuations, which significantly limit the radiation efficiency and beam width of LWAs. It is shown here that the LWA based on CGW compared to PGW can decrease the beam width from 55° to 12° and increase the radiation efficiency from 20% to 50%. A sinusoidally modulated graphene surface is employed to excite the leaky wave antenna. A sinusoidally modulated reactance surface is realized by the modulation of the radius of the cylindrical waveguide. In comparison to other structures, the proposed antenna can be implemented by applying a single voltage to graphene sheets. As a result, the antenna beam direction can be readily changed by varying the applied voltage.

Performance Enhancement of a Planar Slot Phased Array by Using Dual-Mode SIW Cavity and Coding Metasurface

This communication presents a planar phased array designed with an enhanced reflection bandwidth, a wide-angle scan, and a broadband low backscattering. On one hand, an improved substrate integrated waveguide (SIW) cavity-backed slot antenna which supports dual resonant modes is designed and utilized as the array element. The dual-resonance element presents the advantages of wideband reflection, wide-beam radiation, and compact size, which has the benefit for the wideband wide-angle scan of the proposed phased array. On the other hand, a coding metasurface, which consists of four specially arranged unit cells, is presented and surrounds the slot array. Based on the specially designed coding metasurface, the array gain is enhanced and a broadband scattering reduction is realized. Both simulated and experimental results indicate that the designed phased array supports a main-beam scan up to 60° and a 3 dB beam coverage up to 75° in an active reflection band of 10.1-11.6 GHz. Besides, the results also show that the radar cross section (RCS) has the reduction from 6.2 to 16.3 GHz and from 6.2 to 15.2 GHz for TM and TE polarizations, respectively.

Substrate-Integrated-Waveguide-Based Complementary Source Array With Enhanced Beamwidth

A complementary source array with enhanced beamwidth is presented based on the substrate-integrated waveguide (SIW) in this communication. The orthogonal complementary source consists of a SIW slot and a vertical monopole, of which the radiation pattern is heart-shaped, pointing to the direction perpendicular to both slot and monopole. To achieve an enhanced beamwidth from the heart-shaped pattern, the complementary sources are cascaded to form an array. In particular, the slots are etched alternately on both sides of the central axis to achieve an in-phase excitation, while the monopoles are uniformly loaded with an alternate antiphase excitation. This arrangement makes the heart-shaped pattern of each complementary source element alternately point to either side of the array axis, so that the synthesized radiation beamwidth is enhanced in the E-plane. Based on the proposed idea, a nine-element line array is designed, fabricated, and tested. Compared with the same-sized referenced SIW slot array with an E-plane half-power beamwidth (HPBW) of only 80°, the proposed complementary source array extends the HPBW to 180°.

Novel Miniaturized All-Metal UWB Magneto-Electric Monopole (MEM) Antenna for Multistandard Applications

We propose a novel miniaturized all-metal ultrawideband (UWB) magneto-electric monopole (MEM) antenna in this communication. The proposed antenna is composed of a half-ellipse electric monopole and a quarter magnetic loop. The half-ellipse electric monopole consists of a half ellipse with a rectangular slot, a loaded patch, and an L-shape ground fed by a coaxial connector. Enhanced robustness to severe surrounding environments and lower loss can be achieved by employing an all-metal structure instead of the structure including dielectric materials. A prototype was fabricated and measured. Results show that the proposed MEM antenna can operate in the frequency band of 2.5-13 GHz even higher frequency with the miniaturized dimensions of 0.25λ×0.24λ×0.17λ that is much smaller than a magneto-electric dipole. A unidirectional wide beam radiation pattern with a 10 dB front to back ratio can be obtained. Moreover, the group delay is analyzed which reveals the antenna with good time domain characteristics. The proposed MEM antenna can be employed as a multifunctional antenna operating for multistandard communication networks in a limited space.

5G beamforming techniques for the coverage of intended directions in modern wireless communication: in-depth review

AbstractThe growing need of the compact and portable antennas with high speed and low latency wireless communication is the present and future demand of the voice over Internet protocol, on-demand bandwidth, and multimedia applications. Fifth-generation (5G) covers certain low-frequency bands under 6 GHz spectrum, and most of the high-frequency bands under 60 GHz. 5G is the part of the millimeter wave spectrum (30–300 GHz) and is introduced to overcome the problem of spectrum shortage due to exponential enhancement of wireless applications in industry, medical, airborne, radar, satellite, and research fields. The International Telecommunication Union's objective of wireless communications promises to provide higher data rates up to 10 Gbps for 5G mobile users and connectivity to the artificial intelligence devices, along with high spectral efficiencies and enhanced coverage. The users for the 5G require around 5 and 50 Gbps of data rates for low and high mobility, respectively. Beamforming in 5G is the modern powerful technique for the coverage of the intended user/direction using the narrow beam width radiation patterns. A brief survey on 5G beamforming techniques, i.e. analog, digital, hybrid, switched, and adaptive etc. and its types, working algorithms, design of compact antennas, gain, and size/type of the substrates is carried out in this paper. The study of the hybrid coupler, branchline coupler, Wilkinson power divider, and Butler matrix in beamforming is required for 5G smart antennas. Different beam widths like ±15, ±35, ±45, and ±55° etc. are produced for the intended directions using a variety of beamforming techniques. From lower to higher frequency band beamforming applications with Roger's Duroid 4003/4350/5880, tectonic, and aluminum oxide dielectric substrates are discussed here. Various beamforming techniques with their merits, demerits, and applications are included in the paper for the knowledge extension of the beamforming antenna designers and research community.

Low Cost Circularly Polarized Antenna for IoT Space Applications

This work presents the use of a three-element radiating structure for circularly polarized Low-Power Wide Area Network (LP-WAN) communication with space. The proposed structure has a 72 mm × 72 mm × 12 mm compact size with Right-Handed Circular Polarization (RHCP) and a 120∘ wide beamwidth radiation pattern. Printed on low-cost FR4 Epoxy substrate, a feeding network circuit based on Quasi Lumped Quadrature Coupler (QLQC), it achieves a −0.6 dB insertion loss and a very compact size. The final structure has a 69% total efficiency and a 3.14 dBic realized gain.

2-D Wide-Angle Scanning Phased Array With Hybrid Patch Mode Technique

In this letter, a microstrip patch hybrid mode technique is introduced to design a 2-D wide-angle scanning planar phased array. The proposed element consists of a circular patch and four rectangular parasitic patches distributed around the circular patch. In order to obtain wider radiation beamwidth (BW) in two orthogonal azimuth planes, the TM11 mode of the circular patch and the zeroth-order resonant mode of the parasitic rectangular patches are separately excited. Experimental results show that the proposed element can obtain 3 dB BW more than 156° in the two orthogonal azimuth planes. Moreover, an 8 × 8 planar phased array formed by this element can realize wide-angle scanning in a range of about ±65° in the two orthogonal azimuth planes. In the above scanning range, the sidelobe levels of the phased array are always less than −7.8 dB, the scanning gain fluctuation is less than ±1.73 dB, and the main polarizations on the two orthogonal planes are both θ -polarized. In addition, the phased array has a simple structure, a low profile, and convenient fabrication.

Dual-Band Single-Layer Microstrip Patch Antenna With Enhanced Bandwidth and Beamwidth Based on Reshaped Multiresonant Modes

A dual-band single-layer microstrip patch antenna (MPA) with simultaneous improvement in impedance bandwidth and radiation beamwidth is proposed in this communication. The performances of the MPA are implemented by resonating its radiative TM10 and TM12 modes at the lower and upper bands, respectively. Initially, the far-zone radiated fields of the MPA working in the TM10 mode are theoretically investigated. It demonstrates that its E-plane half-power beamwidth (HPBW) in the lower band is significantly widened by removing the array factor between dual equivalent slots. After that, the MPA working in TM12 mode is deeply studied and analyzed. The results depict that its wide E-plane HPBW and low H-plane sidelobe level (SLL) in the upper band could be obtained by reshaping radiation patterns of its improved TM12 mode via the shorting pins. Additionally, a linear slot is cut on the core radiator so as to achieve a good impedance matching. With these arrangements, the E-plane HPBW, H-plane SLL, and impedance bandwidth of this designed MPA can be simultaneously enhanced in the dual bands. Finally, the proposed antenna is fabricated and measured. The experimental results show that the antenna has gained an improved bandwidth ( $\vert S_{11}\vert –10 dB) ranging from 3.45 to 3.77 GHz and 5.75 to 6.04 GHz with two attenuation poles. Most importantly, the HPBW of its E-plane radiation pattern is successfully widened to around 135° over these dual operating bands. Moreover, the high H-plane SLL of the antenna is decreased to about −10 dB in the upper band.

Sinusoidally modulated leaky wave antenna based on cylindrical graphene waveguide

Based on the cylindrical graphene waveguide, the concept and analysis of a leaky wave antenna (LWA) at terahertz band are presented. The proposed structure overcomes the limitations of planar LWA characteristics, such as radiation efficiency and beam width. The values of attenuation and leakage constants can lead to the maximum radiation efficiency and beam width in the planar LWA equal to about 20% and 57°, but in cylindrical LWA equal to about 50% and 12°, respectively. The leaky wave is excited by a sinusoidally modulated graphene surface. A sinusoidally modulated reactance surface (SMRS) allows for a nearly independent control of the phase and leakage constants and thus adjusts the scan angle and radiation efficiency simultaneously. An SMRS was first realized by applying various bias voltages to different gating pads underneath the graphene sheet. Another desirable feature of an antenna is the high value of input impedance, so it can easily be matched to a photomixer.