Polarization Agility Research Articles

The Leaky-Wave Perspective for Array-Fed Fabry–Perot Cavity and Bull’s-Eye Antennas

Two-dimensional leaky-wave antennas (LWAs) are a class of planar, traveling-wave radiators with attractive features of a low profile, ease of feeding, frequency reconfigurability of the radiation pattern, and polarization agility. Their use in conjunction with array feeders has been the subject of various investigations in recent decades, thanks to the additional degrees of freedom provided by the presence of multiple independent sources. Here, we provide a review of some of the most recent and promising array-fed two-dimensional (2-D) LWAs, selecting a couple of the most significant structures in application, namely Fabry–Perot cavity antennas and bull’s-eye antennas, and discussing some of their recently proposed advanced features.

Differentially Fed, 1-D Phased-Array Antenna-on-Display Featuring Wideband and Polarization Agility for Millimeter-Wave Wireless Applications

Differentially Fed, 1-D Phased-Array Antenna-on-Display Featuring Wideband and Polarization Agility for Millimeter-Wave Wireless Applications

Circular polarization-agile and beam switching enabled reconfigurable cavity-backed antenna

In this paper, a circular polarization-agile and beam switching enabled reconfigurable cavity-backed antenna having the ability to steer its radiation beam in different directions is presented. The antenna consists of two E-shaped driven patches, a tunable phase shifter integrated with PIN diodes for pattern switching and four switchable feeding probes for implementing polarization agility. The proposed antenna can simultaneously change its polarization and pattern. Beam switching and polarization agility are independently controlled by altering the OFF-ON states of diodes loaded on the feed network and switchable feeding probes. For validity of the proposed concept, the antenna prototype is fabricated and tested. The proposed antenna has measured impedance bandwidth (S11 < -10 dB) and 3 dB axial ratio bandwidths of 23% and 17.4% respectively for all states over the frequency range 4.7–5.6 GHz. The measured and simulation results show that the antenna can scan up to ± 30° with five reconfigurable beams and two polarizations states for each reconfigurable beam.

Reconfigurable Full-Metal Circularly-Polarized Cavity-Backed Slot Antenna and Array With Frequency and Polarization Agility

In this brief, reconfigurable circularly-polarized (CP) cavity-backed slot antenna (CBSA) and antenna array with frequency and polarization agility are proposed. Two degenerate modes TE101 and TE011 are respectively perturbed by the metal posts along y-axis (named as MP-1) and x-axis (named as MP-2), and independent frequency tuning is obtained. Then, two crossed slots are placed on the top wall to radiate the electromagnetic energy of TE101 and TE011 modes, respectively. In this context, circular polarization can be realized by setting different lengths of MP-1 and MP-2. Besides, reconfigurable polarization between left-hand and right-hand circular polarization can be realized by exchanging the lengths of MP-1 and MP-2. Meanwhile, reconfigurable operating frequency can be realized by simultaneously increasing or decreasing the lengths of MP-1 and MP-2. In addition, a reconfigurable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4{\times }4$ </tex-math></inline-formula> CP array without introducing power dividers and without increasing the number of tuning metal posts is further investigated. Finally, the reconfigurable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4{\times }4$ </tex-math></inline-formula> CP array is fabricated and tested. Reconfigurable frequency, reconfigurable polarization, high total efficiency, and stable radiation pattern are simultaneously obtained. Good agreement between measured and simulated results well validates the proposed design concept.

A Quad-Polarization Reconfigurable Fixed-Frequency Beam-Scanning Leaky-Wave Antenna Based on the Holographic Method for Millimeter-Wave Application

A quad-polarization reconfigurable fixed-frequency beam-scanning leaky-wave antenna (LWA) operating at millimeter-wave Ka-band is presented in this article. A low-loss groove gap waveguide (GGW) structure is employed for low-loss transmission and feeding, above which there locates a metal-covered superstrate. Two rows of inclined slots etched on the metal cover in a staggered arrangement operate as the radiated sources. A modified holographic method is presented, and the hologram can be manipulated by switching the states between “ON” and “OFF” of the p-i-n diodes, and hence the fixed-frequency beam-scanning property with polarization agility of four different polarization states can be realized, including horizontal polarization (HP), vertical polarization (VP), left-handed circular polarization (LHCP), and right-handed circular polarization (RHCP). Besides, measured results of the fabricated antenna are given to verify its performance. The measured peak gains at 30 GHz reach 11.3 dBi in the HP state, 13.0 dBi in the VP state, 11.5 dBic in the LHCP state, and 11.8 dBic in the RHCP state, respectively, with a beam-scanning range of 100° (from −50° to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mathrm{50}^{\circ }$ </tex-math></inline-formula> ), showing good agreement with the simulated results.

Investigation of Multi-Band Reconfigurable Triangular Microstrip Antenna on Magnetic YIG Substrate

Reconfigurable antennas based on magnetised ferrite substrate and electronic components present a remarkable interest for nowadays antennas. The present research contribution deals to investigate an efficient multiband tuneable triangular microstrip antenna with acceptable characteristics, able to operate from 2.6 GHz to 5.8 GHz requiring frequency and polarization agility by dual reconfigurability using a YIG (Yttrium Iron Garnet) substrate and PIN diode. Different magnetic bias fields were applied to the proposed antenna for ON and OFF states. The obtained results and analysis demonstrate the efficiency of magnetic frequency tuning and a high stability of the radiated field, the antenna bandwidth can reach 1300 MHz for ON state, and a maximum tuning range close to 550 MHz is observed. The proposed antenna design exhibits a linear polarization and stable E and H–plane radiation pattern performance at resonance frequencies over the operating bands. These characteristics make the antenna suitable for multiband wireless communications requiring frequency agility.

Electronically Steerable Antennas for Future Heterogeneous Communication Networks: Review and Perspectives

Satellite, fifth generation (5G), and sixth generation (6G) mobile communication systems operating at micro- and millimeter wave frequencies are an essential pillar in advanced network architectures for high-throughput low latency services. The decisive factors for this current development were the significant technological advances accomplished over the last two decades, which meanwhile enable highly integrated, feature-rich, and cost-effective realizations of complete phased array transceiver topologies. Motivated through the today's trend for heterogeneous constellation types to provide truly global coverage, this contribution reviews the current state-of-the-art of electronically steerable antennas for terrestrial and non-terrestrial communication systems up to 100 GHz. First, the potential benefits and limitations of the most relevant technologies are contrasted and put into context with recent system architectures for adaptive beamforming. Their operating principles along with various experimental implementation and achievements providing advanced capabilities such as multi-band/multi-beam operation, polarization agility, and wide-angle scanning are thoroughly presented. Particular emphasis is laid on the review of direct radiating arrays, quasi-optical antenna configurations, and metasurface-based antennas.

Design of Frequency and Polarization Agile Patch Antenna for Wireless Communications

In this paper, a compact frequency and polarization agile patch antenna is presented. The antenna comprises a square patch with truncated corners along with a triangular slot etched at the center of the patch. Pin diodes are used to bridge the gap between the truncated corners and center triangular region with a radiating square patch. By appropriately biasing the pin diodes the antenna achieves frequency and polarization diversity. The antenna achieves five distinct states with three linear polarization (LP) states operating at three different frequencies and two circular polarization (LHCP/RHCP) states operating at the same frequency. The antenna gives a −10 dB impedance bandwidth of 95 MHz (1.825–1.92 GHz) in the GSM band for LP state 1, 115 MHz (2.365–2.48 GHz) in the ISM band for LP state 2, 145 MHz (2.08–2.225 GHz) in UMTS band for LP state 3, 100 MHz (2.1–2.2 GHz) UMTS band for CP state 4 and 5. The antenna attains a measured peak gain of ∼4.8 dBi at LP states and ∼4.54 dBi at CP states in its operating band.

Polarization Agile Beam Steering by Subarray Antenna Module Design to Compensate Wide-Angle Polarization Discrepancy of User Equipment Antenna Radiations at mmW Frequencies

An antenna-in-module (AiM) architecture at millimeter-wave frequencies for a base transceiver system (BTS) is developed for electromagnetic (EM) radiation with an agile polarization tunable capability. This may reduce the polarization mismatch to a user equipment (UE) antenna, where the mismatch becomes severe in wide-angle scans. The AiM first implements a dual-polarization feature on its antenna elements and then integrates active radio frequency (RF) phase shifters and power amplifiers/attenuators to provide dynamically adjustable weightings. Considering the received fields of a UE antenna, the weightings of the AiM antennas are appropriately tuned to obtain the maximum signal strength from the UE antenna. In this article, the theoretical concept and the antenna architecture are presented. Full-wave simulations using HFSS and the measurement results of the AiM prototype are presented to validate its feasibility.

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.

A compact TM03 mode penta‐polarization agile MSA for interference mitigation in 5G ultra‐dense point to point environment

Signal interference in the recent 5G ultra-dense environment is becoming severe due to the co-existence of large RF nodes operating in the constrained spectrum. In this article, a polarization agile approach for the designing of an RF system is studied to mitigate interference issues besides the communication and signal processing approach. A compact single-fed single layer penta-polarization agile higher-order microstrip patch is analyzed probably for the first time in the literature. The proposed antenna possesses a very low profile of less than 0.01 λ (λ free-space wavelength). Reconfigurable orthogonal feeding with switches is connected with the horizontal and vertical patch edges. Subsequently, these are excited separately and simultaneously using switchable PIN diodes and appropriate bias networks to realize horizontal, vertical, and 45° slant polarization states. Successively, diagonal patch corners are truncated to initiate right and left-hand circular polarizations. Slots are etched on specific orientation of currents on the patch surface to improve side-lobe levels. A prototype is analyzed, simulated, and fabricated at TM03 mode and operating at 5.8 GHz band with penta-polarization agility. A consistent 11 dBi realized broadside gain is measured covering the 10 dB reflection loss and 3 dB axial ratio bandwidth in both the principal planes.

Dual polarized designs of square microstrip antenna for GSM and LTE applications

SummaryTo obtain the polarization agility in wireless applications, the dual polarized wideband or multi‐band antennas are required. In this paper, modified designs of square microstrip antenna by employing overlap offset parasitic patches are proposed for the dual polarized wideband and multi‐band response. Due to the optimum spacing in between the fundamental TM1045 and TM01135 modes along with TM11 mode, on a total substrate thickness of 0.075λg, the proposed design yields bandwidth of more than 550 MHz (&gt;50%), exhibiting the dual polarized characteristics. A similar design is presented on a thinner suspended substrate. Here, on the substrate thickness of 0.035λg, it yields impedance matching at higher order TM20 mode, which along with TM1045, TM01135, and TM11 modes exhibits triple band response. An impedance bandwidth of 3.4%, 17%, and 4.7% is realized in the three bands with a broadside gain of more than 6 dBi. The proposed design satisfies the requirements of GSM 810/GSM900/LTE applications. In each design, simulated results have been experimentally verified that show close agreement.

A Polarization and Beam Steering Reconfigurable Cavity-Backed Magneto-Electric Dipole Antenna Array Using Reflection-Type Phase Shifter

This article introduces a reconfigurable cavity-backed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\,\,\times4$ </tex-math></inline-formula> magneto-electric (ME) dipole antenna array with agile polarization and steerable beam features for both linear and circular polarizations (CPs). The proposed ME dipole element backed by a cavity can reduce the mutual coupling and enhance the scanning performance of the antenna array. To achieve continuous beam-scanning ability, reflection-type phase shifters are designed with varactor diodes and integrated with the feeding network. The polarization agility is determined by embedding two switchable cross strips into the ME dipole element. By manipulating the states of the two switchable cross strips through dc bias controls, three different polarization states including linear polarization (LP), left-hand CP (LHCP), and right-hand CP (RHCP) can be realized. For verification, a prototype of the antenna array was fabricated and measured. A good agreement between the simulation and the measurement is obtained, thus validating the multiple reconfigurable capability of the antenna array in polarization and radiation pattern. The measured results demonstrate that the beam can be scanned continuously in a range between ±40° for the three polarization states. Meanwhile, the measured overlapped bandwidth for the reflection coefficient ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \text{S}_{11}\vert \le -10$ </tex-math></inline-formula> dB) and the 3 dB axial ratio (AR) is from 2.0 to 2.4 GHz for all states.

A Wideband Subwavelength-Thick Circularly Polarized Discrete Lens Using Dielectric-Coated Polarization-Twisting ME-Dipole Elements

This letter presents a circularly polarized (CP) discrete lens with large operating bandwidth and optimized thickness. A wideband polarization-twisting unit cell, which enables the polarization agility of the lens at a pixel level, is developed using the magnetoelectric-dipole-based transmissive element. By comprehensively utilizing the rotation freedom of the probes at the transmitting and the receiving layers as well as incorporating additional dielectric-coating layer, an over-2-bit CP discrete lens is achieved, demonstrating a wide axial ratio (AR) bandwidth, an improved antenna gain, and a well-controlled lens thickness. A maximum gain of 21.5 dBic and an overlapped 3 dB gain and AR bandwidth of 47% are experimentally achieved with the designed 0.66-λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> -thick, 256-element discrete lens.

Polarization-Agile Circular Polarized Antenna Based on Proximity Feeding Technique

In this letter, the design and experimental validation of polarization-agile circular polarized antenna are presented. The antenna is comprised of a patch antenna with truncated slits and two proximity feedlines. The antenna produces a vertical linear polarized wave when it is fed by a proximity feedline. Horizontal linear polarized wave is then generated by applying a potential difference between two proximity feedlines. The quadrature phase difference between two orthogonal polarized waves is created by adding truncated slits into the patch antenna. By swapping the polarity of the proximity feedlines, polarization sense can be changed. The distributed circuit model is presented to describe the working mechanism of the antenna. Patch antenna with circular polarization agility is then validated through passive-type and active-type switching circuits. The measured axial ratio bandwidth is 4.085% (100 MHz), and the fractional impedance bandwidth is greater than 7% for the left-handed and right-handed circular polarized radiations.

Dual polarized triple wideband circular microstrip antenna for GSM and satellite applications

Dual polarized triple frequency wideband design of circular microstrip antenna using the combination of slots and stub is proposed. This triple wideband response is explored by using a thinner substrate in the air suspended configuration that enables the input impedance matching at various higher order resonant modes together with the fundamental mode. Amongst different variations, modifications in terms of the slots and stubs degenerates and optimizes the spacing in between the fundamental and higher order modes, which leads to dual polarized wideband response. On air suspended FR4 substrate with thickness of 0.055λg, optimized single patch configuration yields dual polarized triple wideband response at 856, 1177, and 1783 MHz respectively giving frequency ratio of 1:1.37:2.0. It yields impedance bandwidth of 8.4%, 11.5%, and 11.4% at the three frequencies with respective broadside gain of 7.4, 6.5, and 3.5 dBi. The proposed configuration yields frequency and polarization agility satisfying the requirements of GSM850/navigation satellite/GSM 1800 applications.

Agile multi-beam front-end for 5G mm-wave measurements

AbstractThe 5th generation new radio (5G NR) standards create both enormous challenges and potential to address the spatio-spectral-temporal agility of wireless transmission. In the framework of a research unit at TU Ilmenau, various concepts were studied, including both approaches toward integrated circuits and distributed receiver front-ends (FEs). We report here on the latter approach, aiming at the proof-of-principle of the constituting FEs suitable for later modular extension. A millimeter-wave agile multi-beam FE with an integrated 4 by 1 antenna array for 5G wireless communications was designed, manufactured, and verified by measurements. The polarization is continuously electronically adjustable and the directions of signal reception are steerable by setting digital phase shifters. On purpose, these functions were realized by analog circuits, and digital signal processing was not applied. The agile polarization is created inside the analog, real-time capable FE in a novel manner and any external circuitry is omitted. The microstrip patch antenna array integrated into this module necessitated elaborate measurements within the scope of FE characterization, as the analog circuit and antenna form a single entity and cannot be assessed separately. Link measurements with broadband signals were successfully performed and analyzed in detail to determine the error vector magnitude contributions of the FE.

A Reconfigurable 1 × 4 Circularly Polarized Patch Array Antenna With Frequency, Radiation Pattern, and Polarization Agility

In this communication, the design and experimental verification of a reconfigurable 1 ×4 circularly polarized (CP) patch array antenna with frequency, radiation pattern, and polarization agility are reported. An orthohexagonal patch element antenna with three groups of parasitic patch and varactor diode is adopted to enable frequency and polarization reconfiguration. By properly adjusting the dc voltage applied on the three groups of varactor diode, the operating frequency can be tuned continuously, and the polarization can be switched simultaneously between left-handed CP (LHCP) and right-handed CP (RHCP). Four switchable feeding probes integrated with a designed single-pole four-throw (SPFT) switch are used to feed the element antenna for achieving different initial phase. Hence, by properly switching feeding probes for the four elements, the radiation beam of the array antenna can be dynamically reconfigured among five different beam states. To verify the proposed concept, a full functional prototype was fabricated and characterized for four different frequency bands with all polarization and beam states. A good agreement between the simulation and measurement is obtained, thus validating the multiple reconfigurable capability of the array antenna in frequency, pattern, and polarization.

A Frequency and Polarization Agile Disc Monopole Wearable Antenna for Medical Applications

A Frequency and Polarization Agile Disc Monopole Wearable Antenna for Medical Applications

Development of Enabling Technologies for Ku-Band Airborne SATCOM Phased-Arrays

In the paper the development of a fully electronic transmit-receive phased-array antenna system in Ku-band for aircraft communications via satellite is presented. Particular emphasis has been placed in the improvement of the following key elements: a dual-polarization self-diplexing radiating element, a transmit/receive active module with full polarization agility based on a digital vector modulator and a SiGe multinode MMIC. The optimized antenna elements enable a significant improvement towards the realization of a future affordable commercial product for satellite communications.