Broadside Beam Research Articles

Design and optimization of dielectric resonator based MIMO antenna with beam tilting at mm-wave for enhanced 5G communication using machine learning

In this paper, a dual-port ceramic-based multiple-input multiple-output (MIMO) antenna is designed for operation at mm-wave frequencies. The design incorporates a partially reflecting surface (PRS) positioned above the dual-port antenna to facilitate beam tilting. Additionally, various machine learning (ML) algorithms are utilized to optimize the unit cell length and the distance between the Dielectric Resonator Antenna (DRA) and the PRS, thereby achieving the desired beam tilting characteristics. The ceramic element is excited through an aperture, which generates the HEM11δ mode in the cylindrical dielectric resonator antenna (CDRA). The proposed antenna demonstrates excellent port isolation, exceeding 35 dB, and operates effectively within the 25.9–27.4 GHz frequency range. The PRS enables a broadside beam tilt of ±30 degrees, incorporating pattern diversity into the design. These characteristics make the proposed antenna an ideal candidate for mm-wave vehicle-to-vehicle and 5G communication systems.

Low-profile Dual-polarized Filtering Antenna with Improved Gain and Impedance Bandwidth using Characteristic Mode Analysis

A low-profile dual-polarized filtering microstrip patch antenna (MPA) with improved gain and bandwidth is realized without requirement of filtering circuit. Herein, the characteristic mode analysis (CMA) method is adopted to analyze the antenna performances. Initially, the resonant modes of the MPA are deeply analyzed, which indicates that its resonant frequencies of CM1 and CM3 could be moved close to each other by loading slots and shorting pins, thus broadening the impedance bandwidth. Then, the influence of the slots on radiation patterns of the antenna is further studied. The results demonstrate that the non-broadside radiation beam of its CM1 could be reshaped as the broadside beam, and the sidelobe level of its CM3 could be reduced by cutting the slots, leading to the improved gain. After that, the effect of the pins on the gain-response is investigated, It shows that the gain nulls of the MPA could be controlled at both lower and upper bands, especially for the non-filtering scheme. Finally, the proposed dual-polarized antenna is fabricated and tested. The results prove that its impedance bandwidth reaches to about 7.4% with a low-profile of about 0.038 free-space wavelength. Besides, a stable enhanced gain of around 10 dBi is achieved over the operating band.

Intelligent metasurface based antenna with pattern and beam reconfigurability for internet of things applications

The Internet of Things (IoT) devices are distributed randomly in the environment, antennas with multiple switched beams are needed to unlock the full potential of communication systems. This paper presents an intelligent metasurface (IMS) based pattern and beam reconfigurable antenna for indoor as well as outdoor IoT applications including V2X and 5 G Small Cell. The IMS based antenna system consists of a wideband monopole and a programable IMS acting as a reflector. The single–layered metasurface is comprised of 4×4 square ring-shaped unit, where each unit cell can be controlled by a pair of four diodes. Due to the separate control of each unit cell, the shape and size of the reflector can be controlled, resulting in different radiation patterns. The system offers various radiation patterns, starting from omni–directional to broadside, with single or dual beams, along with beam–steering both in elevation and azimuth plane. The antenna system offers a peak gain up to 8.89 dBi with an operational bandwidth of 4.95–7.6 GHz. To validate the design concept, the system is fabricated and tested. A microcontroller is utilized for the switching IMS configuration. The high agreement between simulated and measured results, combined with the low profile, high gain, pattern–beam reconfigurability make the proposed antenna a suitable candidate for the indoor IoT devices along with outdoor application not limited to V2X communication systems as well as for small cell in smart cities.

Exploring the Beam Squint Effects on Reflectarray Performance: A Comprehensive Analysis of the Specular and Scattered Reflection of the Unit Cell.

In this article, the phenomena of beam deviation in reflectarray is discussed. The radiation pattern of the unit cell, which plays a vital role in shaping the beam of the reflectarray, is analyzed by considering undesired specular and scattered reflections. These unwanted reflections adversely affect the pattern of the single unit cell, thereby reducing the overall performance of the reflectarray. To conduct our investigations, three cases of reflectarray-i.e., (i) a center-fed with broadside beam (Case-I), (ii) a center-fed with the beam at 30° (Case-II), and (iii) off-center-fed with the beam at 30° reciprocal to feed position with reference to the broadside direction (Case-III)-are simulated. Different degrees of beam deviation are analyzed in each reflectarray by assessing the radiation pattern of a single element. The simulation results shows that maximum of 0°, 3.4°, and 0.54° beam squint across the bandwidth found in Case-I, Case-II, and Case-III, respectively; this leads to aperture efficiencies of 31.2%, 11.9%, and 31.2%, respectively. The significance of specular reflections is further confirmed by half (left half and right half) aperture analysis of Case-II. This involves simulating the half-plane aperture illuminated by horn antenna, resulting in a distinct beam angle at the same frequency. However, deviations of -4.71 to +4.1 for the left half aperture and -1.82 to +1.1 for the right half aperture are noticed. Although the analysis specifically focuses on the three cases of the reflectarray, the proposed methodology is applicable to any type of reflectarray. The study presented in this work provides an important insight into the practical aspects of reflectarray operation, particularly in terms of quantifying undesirable effects that are normally overlooked in the design of this class of arrays. To achieve a good performance, a new design of the dielectric loaded horn feed is proposed. This design approach is both simple and applicable to any reflectarray, with the added benefit of maintaining a low profile for the RA. Moreover, this work holds significant potential for remote sensing satellite systems as beam deviation can adversely impact data collection accuracy and compromise observation precision, resulting in distorted images, reduced data quality, and overall hindrance to the system's performance in capturing reliable information.

Low-profile meander metaline antenna for dual-band circularly polarized broadside beam formation

Low-profile meander metaline antenna for dual-band circularly polarized broadside beam formation

Broadband inhomogeneous lens with conical radiation pattern

This manuscript presents a lens antenna with simultaneous broadside and conical beams. The lens is designed for the Ku band using the ray inserting method. The proposed conical radiation pattern is broadband due to good matching with the source and surroundings. The simulation is conducted using the CST microwave studio solver. Instead of complex antenna shapes used in other works, a simple circular patch ring and RF connector are used as the lens feed to generate broadside and omnidirectional conical patterns, respectively. To validate the performance of the designed lens and its two-port feed antenna, the lens structure is realized and fabricated using the 3D printing method. Polyethylene terephthalate glycol (PETG) plastic material is utilized for constructing the lens in this work. The electromagnetic characteristics of PETG in the Ku band are accurately measured. The results of simulations and experiments demonstrate the good performance of the designed lens over a wide frequency bandwidth. The advantage of this designed structure over other works is its high gain and broad bandwidth.

Power Pattern Synthesis With Peripherally Excited Phased Arrays

Peripherally excited phased arrays have been demonstrated as an effective way to realize some aspects of phased array performance with a simple design and reduced cost. This work develops a method to realize shaped beams with peripherally excited arrays by controlling the relative magnitude and phase of the antenna’s peripheral sources. Through a simple model of fields in a parallel-plate waveguide, a linear system of equations can be defined and solved to find the peripheral source excitations that best approximate a desired field pattern. This model is used to solve for a uniform broadside beam, and yields a higher aperture illumination efficiency than a broadside beam obtained from an equal-amplitude excitation. A cosecant beam is also synthesized, showing good agreement with the goal beam pattern. The linear system of equations can be easily integrated into other beam synthesis techniques for increased design flexibility. A particle swarm optimization is used to solve for controlled side lobe-levels, flat-top and multi-beam patterns. Beams realized with full-wave simulation show good agreement with the ideal and predicted beams.

Circular Polarization Annular Leaky-Wave Antenna with Conical and Broadside Beams

In order to properly cover different scenarios, radiation patterns of antennas should be accordingly designed. However, most antennas are unable to provide either broadside beams or designable conical beams, which are the typically used radiation patterns for radio coverage, based on one single-structure format through adjusting parameters before fabrication. In this paper, a planar circular polarized (CP) annular leaky-wave antenna (LWA) is proposed, which is realized on an annular substrate-integrated waveguide (SIW). A broadside beam or a conical beam could be easily obtained through fabricating the LWA with different structural parameters. The operating frequency is 5.75 GHz. The LWA allows only the −1st spatial harmonic to radiate, while the fundamental wave and other spatial harmonics are suppressed in slow wave mode. In order to validate the design effectiveness, two examples for broadside beam and conical beam radiation are fabricated and measured. The measurement results show good agreement with the simulation results. The broadside beam LWA shows a gain of 9.75 dBic and the conical beam LWA with a beam angle of 13° has a gain of 7.93 dBic. The proposed LWA presents promising radiation performance and is a good candidate for wireless communication applications.

Ka-Band High-Efficiency Leaky-Wave Broadside Array Antenna Based on Dielectric Image Lines

Based on a novel perturbation structure combining square hole and metal strip, a Ka-band high-efficiency dielectric image line (DIL) leaky-wave antenna (LWA) array with broadside beam is proposed in this paper. Compared with the conventional periodic unit, a larger control range for the radiation capacity is realized, which is applied to the design of 20× 8 DIL array with uniform illumination. Moreover, due to the low losses of the DIL and the waveguide feeding network, the high efficiency performance has been achieved. The measured maximum gain is 28.24 dBi at 35 GHz, which corresponds to the radiation efficiency and aperture efficiency of 77.69% and 54.39%, respectively. The stable and available broadside radiation pattern have been achieved in the frequency range of 34.4GHz-35.4GHz. The advantages of high efficiency and low manufacturing cost of the proposed antenna make it an excellent candidate for mm-wave applications.

A Wideband Multibeam Pillbox Antenna Based on Differentially Fed Leaky-Wave Array

In this letter, a compact wideband multibeam pillbox antenna is proposed based on differential feeding technology. The proposed design focus on extending the operating frequency bandwidth of the leaky-wave antenna (LWA) array with a fixed broadside beam, since the bandwidths of the existing pillbox antennas are always limited by the radiators, especially considering the standard printed circuit board technology with limited layers. To overcome this limitation, a differentially fed LWA is used as the radiator. The two subarrays of the LWAs are excited with oppositely propagating waves through a coupled slot, generating two oppositely directed beams whose combination can produce a fixed broadside beam over a wide operating bandwidth. A 14-element LWA array is fabricated with a pillbox beamforming network (BFN) to verify its design theory. The simple feeding structure of the LWA makes the LWA array can be stacked on the top of the pillbox BFN, achieving antenna miniaturization. The measured results show that the proposed antenna can achieve the −10 dB impedance matched bandwidth from 14.0 to 16.0 GHz and seven beams with ±34° beam scanning range. The broadside beam has a gain variation range of 16.8–20.2 dB over the operating band.

Universal and Non-Iterative Design Method for In-Phase Radiation of Microstrip Traveling-Wave Series-Fed Antenna Arrays

Microstrip traveling-wave series-fed antenna arrays (MTSAAs) have been popularly developed for radar systems in the millimeter-waveband. Because the antennas are connected and fed in series in MTSAA, in-phase radiation of the antenna elements with properly tapered amplitude for achieving a broadside beam with a low sidelobe level (SLL) is challenging. Although the reported series-fed patch and comb-line arrays accomplished the goal, design equations for the optimum distances between antenna elements in the series-fed array do not guarantee in-phase radiation due to the mutual coupling in array structures. Therefore, optimization of the distances in the array using full-wave simulations is inevitable. In this article, we propose the first universal and non-iterative design equation that compensates for the phase offset generated in patch and comb-line MTSAAs and successfully found optimum distances for broadside beams with low SLLs without optimization. Finally, we fabricated both MTSAAs with ten elements operating at 76.5 GHz and demonstrated almost 13 dB boresight gain and low SLLs near −18 dB without a beam tilt.

Fundamental/harmonics beam control using 1-bit space time-modulated plasma DMA

This paper investigates a space-time modulated digital metamaterial array (DMA) based on reconfigurable plasma ionization. The DMA consists of 8 × 8 unit-cell elements with total dimensions of 120 × 120 × 3.2 mm3. Each unit-cell consists of a ring container filled with argon gas and is backed with a grounded dielectric substrate. The argon gas is ionized into a plasma state through metallic electrodes. The logic state of the unit cell is controlled via the changing of the plasma frequency, {omega }_{p}. The value of {omega }_{p}=6times {10}^{11}mathrm{ rad}/mathrm{sec} represents logic “0”, and {omega }_{p}=8times {10}^{11} mathrm{rad}/mathrm{sec} represents logic “bit 1”. The periodic time switching of the plasma ionization controls the radiation at the fundamental and harmonic frequencies. The on-time instants and on-time durations control the number of radiated beams, their directions, amplitudes, and side-lobe levels. Different time-switching sequences are investigated for beam steering, dual-sum beams, broadside beams, end-fire beams, multi-beams, and fan-shaped beams for wireless communications applications. The DMA was investigated under different switching sequences for phase-modulation and amplitude-modulation schemes. A full-wave simulation CST Microwave Studio simulator is used to analyze the proposed DMA and the results are compared with ideal point sources array excited with the same switching sequences.

Multi-Feed Metasurface Antennas: Direct Numerical Design and Experimental Validations

This paper provides new designs and realizations of leaky-wave (LW) metasurface (MTS) antennas fed at multiple points. The design technique is based on the direct integral-equation solution by the Method of Moments (MoM). The unknown is no longer the current distribution, but the impedance profile itself. The method can be used to generate any shaped radiation pattern in amplitude, phase, and polarization, provided that the antenna area and the feeder illumination are consistent with the shape of the desired radiation pattern. The algorithm can also be used to design multi-functional antennas (multibeam, multiband, dual-polarizion, etc). While multiple feeds are traditionally used to implement multiple fonctionnalities, they may also be required for the efficient generation of a single shaped beam, thus leading to a higher surface-wave (SW) to LW conversion efficiency. The present paper shows for the first time, two realizations of MTS design with the integral equation formalism, which require the usage of multiple feeds: a circularly polarized sectoral conical beam and a dual-polarized broadside beam MTS antenna. The good comparison between measurements and numerical predictions shows the effectiveness of the design method.

Circularly Polarized Broadside Beam Radiated From a Large, Low-Profile Metaloop Antenna

The area within a loop antenna can be used for inserting additional components (such as mounting hardware) if this does not cause the antenna characteristics to degrade. This article discusses a circularly polarized (CP) metaloop antenna that has a loop circumference of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C} _{\mathrm {LOOP}}= 1 \lambda _{\text {g}}= n\lambda _{0}$ </tex-math></inline-formula> with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n&gt;1$ </tex-math></inline-formula> , thereby creating a large area within the loop, where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{\text {g}}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$= 2~\pi /\beta $ </tex-math></inline-formula> ) and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$= 2~\pi /k_{0}$ </tex-math></inline-formula> ) are the guide wavelength of the current on the loop and the free-space wavelength, respectively. Values for the propagation phase constant within the range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-1 &lt; \beta /k_{0} &lt; 0$ </tex-math></inline-formula> are used in this article. It is found that metaloop antennas for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n = 3$ </tex-math></inline-formula> , 4, and 5 generate a CP broadside beam (axial beam) with gain bandwidths (GBWs) of approximately 6%, 5%, and 4%, respectively. The VSWR across the GBWs is less than two and the axial ratio is less than 3 dB. The radiation efficiencies for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n=3$ </tex-math></inline-formula> , 4, and 5 are approximately 48%, 69%, and 83%, respectively. When a conducting disk (as a generalization for the presence of additional components) is inserted into these metaloop antennas, the antenna characteristics are not degraded until the disk and the metaloop are in close proximity (proximity coupling occurs).

3D Printed Directive Beam-Steering Antenna Based on Gradient Index Flat Lens With an Integrated Polarizer for Dual Circular Polarization at W-Band

In this communication, the design of a circularly polarized (CP) perforated gradient index (GRIN) flat lens antenna with directive beam-steering properties is presented for millimeter-wave applications at W-band (75–95 GHz). The dielectric lens, fed by an open-ended square waveguide (SWG) located in the lens focal plane, enhances the radiation in a particular direction, generating a high-directivity beam with planar wavefront. The integration of a dielectric polarizer with the lens allows the conversion from a linearly polarized (LP) incident wave to a CP-emitted wave over the whole bandwidth. Horizontally and vertically polarized waves, achieved by the excitation of the fundamental SWG TE01 and TE10 modes are transformed into left-hand CP and right-hand CP waves, respectively. A ±30° scan range in both azimuth and elevation planes is demonstrated for the whole frequency range, attained by displacing the feed along the focal plane of the lens. Lens and polarizer are manufactured as a single piece by stereolithography (SLA) 3-D printing technology with Form 3 Formlabs 3-D-printer. Measured results show maximum measured directivity values that range from 23.5 to 23.8 dB, a remarkable circular polarization purity as a wide axial ratio bandwidth of 20.58% (< 3 dB), from 77.5 to 95 GHz, is achieved for the principal beam steers and an aperture efficiency for broadside beam direction between 90.32% and 57.34% in the frequency band of interest.

A Low-Cost and Low-Profile Electronically Programmable Bit Array Antenna for Two-Dimensional Wide-Angle Beam Steering

An electronically programmable bit array antenna (PBAA) is designed with a low profile ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.09\lambda _{0}$ </tex-math></inline-formula> at 11 GHz) and 2-D wide-angle beam steering. The planar PBAA is composed of 8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times8$ </tex-math></inline-formula> elements, and each of them can be individually addressed through the meticulously designed dc bias. By controlling two PIN diodes and four varactor diodes embedded, the PBAA element provides a maximum phase shift of 337.5° and 16 (4 bit) phase coding states with a 22.5° regular interval. The design is verified through simulations and measurements. The experimental results of the fabricated sample exhibit a broadside gain of 16 dBi, corresponding to the radiation efficiency of 33.1%, and 3 dB gain bandwidth of 11.8%. The sidelobe and cross-polarization levels of the broadside beam are below −19.6 and −30 dB, respectively. Moreover, the main beam is capable of scanning in the range of ±60° <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$ </tex-math></inline-formula> ±40°, and the gain fluctuations in E- and H-planes are less than 3.6 and 3 dB, respectively. The design provides flexible 2-D beam-scanning capability while being low cost, low profile, low complexity, and low power consumption, which will benefit various applications with sensing and wireless communication through electromagnetic (EM) waves.

A Planar 4-Bit Reconfigurable Antenna Array Based on the Design Philosophy of Information Metasurfaces

Inspired by the design philosophy of information metasurfaces based on the digital coding concept, a planar 4-bit reconfigurable antenna array with low profile of 0.15 λ 0 (where λ 0 is the wavelength) is presented. The array is based on a digital coding radiation element consisting of a 1-bit magnetoelectric (ME) dipole and a miniaturized reflection-type phase shifter (RTPS). The proposed 1-bit ME dipole can provide two digital states of “0” and “1” (with 0° and 180° phase responses) over a wide frequency band by individually exciting its two symmetrical feeding ports. The designed RTPS is able to realize a relative phase shift of 173°. By digitally quantizing its phase in the range of 157.5°, additional eight digital states at intervals of 22.5° are obtained. To achieve low sidelobe levels, a 1:16 power divider based on the Taylor line source method is employed to feed the array. A prototype of the proposed 4-bit antenna array has been fabricated and tested, and the experimental results are in good agreement with the simulations. Scanning beams within a ±45° range were measured with a maximum realized gain of 13.4 dBi at 12 GHz. The sidelobe and cross-polarization levels are below –14.3 and –23 dB, respectively. Furthermore, the beam pointing error is within 0.8°, and the 3-dB gain bandwidth of the broadside beam is 25%. Due to its outstanding performance, the array holds potential for significant applications in radar and wireless communication systems.

Wideband Polarization Agile Dielectric Resonator Antenna With Reconfigurable Broadside and Conical Beams

A new broadside and conical beam reconfigurable dielectric resonator antenna (DRA) with three orthogonal linear polarizations (LPs) and two orthogonal circular polarizations (CPs) agility is presented. It consists of a quad-strip-fed DRA element and a reconfigurable feeding network. First, the DRA element is designed to make unidirectional <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm{HEM}}_{11 \delta }$ </tex-math></inline-formula> mode and omnidirectional <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm{TM}}_{01 \delta }$ </tex-math></inline-formula> mode operate in the same wide band by tactfully removing a concentric annular column from its interior. Furthermore, a center-loaded metal post helps to improve the impedance matching of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\mathrm{TM}}_{01 \delta }$ </tex-math></inline-formula> resonance significantly. Afterward, the switchable feed network is designed to implement diverse phase distributions of four output ports, i.e., providing the quad-port in-phase excitation, dual-port differential excitations, and quad-port sequentially rotated phase excitation strategies for a vertical LP, ±45° slant horizontal LPs, and two CPs, respectively. Finally, a fully functional prototype is designed, fabricated, and measured to validate the design. The measured results show that the overlapping impedance bandwidth of 36.8% for all the states and the axial-ratio bandwidth of 33.8% for the CPs are obtained.

Millimeter-Wave Slot-Based Cavity Antennas With Flexibly-Chosen Linear Polarization

Slot-based cavity antennas are hailed as promising candidates for millimeter-wave applications. Nevertheless, the linear-polarization (LP) angle of their broadside main beam is limited by the slots etched on the cavity’s top surface. In this work, an innovative technique is developed to significantly improve the selection flexibility of their LP inclination angle. It is attained by an integration of a single-layer, closely spaced C-shaped patch surface. A TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">710</sub> -mode slot-based cavity antenna is employed as the base configuration, which radiates a broadside beam with its LP along <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\phi = 90^{\circ }$ </tex-math></inline-formula> . To effectively predict and monitor the polarization conversion of the surface-integrated TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">710</sub> -mode cavity antenna, an analysis method using a unit cavity extracted from its original cavity antenna is presented. A subsequent surface-integrated system with the specified 45° LP was then simulated, fabricated, and measured. The measured results validate that a 45° LP state is achieved with an operating bandwidth from 33.3 to 36.5 GHz. Further investigation is conducted to flexibly choose the LP direction from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\phi = 15^{\circ }$ </tex-math></inline-formula> to 165°. Two more examples with the fabricated antenna prototypes successfully radiate the specified <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\phi = 15^{\circ }$ </tex-math></inline-formula> and 75° LP beams, respectively. This near-field polarization conversion surface can be generalized to cavities with different resonant modes.

Compact planar ultra‐wideband pattern diversity antenna

AbstractA two‐port planar ultra‐wideband (UWB) pattern diversity antenna is proposed in this letter. The design consists of an array of two rotated identical monopole antennas and two feeding ports with 0° in‐phase and 180° out‐of‐phase excitations. The single monopole antenna includes a circular patch, a rectangular truncated ground plane and a fork‐shaped feeding structure. In this antenna, a modified partial common ground plane is used to enhance the input matching, increase the isolation between antenna elements and improve the desired radiations. The measured results show an |S11| &lt; −10 dB bandwidth ranging from 2 to over 20GHz, with conical and broadside beams, high efficiency, and good isolation across the entire UWB band. Also, the proposed antenna exhibits a smaller footprint, larger bandwidth, and more straightforward design compared with the existing designs. To the best of authors’ knowledge, all these characteristics have never been presented in previously reported UWB pattern diversity antennas.