Cross-polarization Discrimination Research Articles

ВИСОКОЕФЕКТИВНИЙ ХВИЛЕВОДНИЙ ПОЛЯРИЗАТОР ДЛЯ СУПУТНИКОВИХ ІНФОРМАЦІЙНИХ СИСТЕМ

У сучасних супутникових інформаційних системах та безпровідних системах передачі даних широко використовують сигнали із коловими поляризаціями. Сигнали цього типу вимагають застосування спеціальних антенних систем із поляризаційним обробленням. Такий підхід дає можливість удвічі зекономити частотні ресурси, які є обмеженими. У результаті збільшується інформаційна ємність каналів передачі інформації в супутникових та інших інформаційних системах. Базовим елементом антенних систем із коловими поляризаціями є поляризатор. Такий пристрій здійснює перетворення електромагнітних хвиль із круговою поляризацією в лінійно поляризовані хвилі або навпаки. Використання поляризатора та ортомодового перетворювача в антенних системах забезпечує перетворення поляризації сигналів із одночасною передачею їх до розв’язаних хвилеводних каналів. Стаття містить результати аналізу та оптимізації нового високоефективного хвилеводного поляризатора для супутникових інформаційних систем. Конструкція розробленого поляризатора складається із хвилеводу квадратного перерізу з чотирма діафрагмами. Виконано оптимізацію поляризатора для його застосування в робочому діапазоні частот від 10,7 ГГц до 12,8 ГГц. Проаналізовано й оптимізовано фазові, поляризаційні характеристики та характеристики узгодження із застосуванням чисельного методу скінченного інтегрування. Розроблений хвилеводний поляризатор із чотирма діафрагмами забезпечує диференційний фазовий зсув 90° ± 3,5°, коефіцієнт стійної хвилі з напругою, меншою 1,24, коефіцієнт еліптичності, менший 0,53 дБ, кросполяризаційну розв’язку, вищу 30,3 дБ. Таким чином, створений новий поляризатор на основі квадратного хвилеводу з чотирма діафрагмами забезпечує якісну роботу в усьому робочому Ku-діапазоні частот 10,7–12,8 ГГц. Пристрій може широко використовуватися в сучасних антенних системах із поляризаційним обробленням сигналів у телекомунікаційних, радіолокаційних і супутникових інформаційних системах.

3D Printing of a Monolithic K/Ka-Band Dual-Circular Polarization Antenna-Feeding Network

In this paper, a Ka/K-band antenna-feeding network in dual-circular polarization is reported. The design of the system was carried out in view of its monolithic manufacturing through selective laser melting in AlSi10Mg alloy. As a proof-of-concept for satellite telecommunication multi-beam applications, the feeding network operates in the K band (19.25, 20.75) GHz and in the Ka band (27.0, 29.0) GHz. The system provides four rectangular-waveguide ports and a common dual-polarized circular-waveguide port to be connected to the feed horn. The prototype exhibits measured values of in-band return loss better than 28 dB and a port-to-port isolation better than 19 dB (in polarization) and 50 dB (in frequency). The cross-polar discrimination is higher than 20 dB. In this regard, an elliptical-waveguide line was specifically designed and manufactured to recover a value higher than 30 dB in both frequency bands. The line can be easily integrated in the feed horn to be connected to the feeding-network thanks the ease of customization provided by 3D printing. The insertion losses are lower than 0.5 and 0.2 dB in the K and Ka bands, respectively. The weight of the prototype is approximately 130 g.

Millimeter-Wave Propagation Measurement and Modeling in Indoor Corridor and Stairwell at 26 and 38 GHz

Accurate propagation characteristics are essential for future indoor millimeter-wave (mmWave) small cell network planning. This paper presents propagation measurements at 26 GHz and 38 GHz which are important candidate bands for fifth generation mmWave communication. Measurements are conducted in an indoor corridor, as well as a stairwell whose mmWave channel is seldom investigated before. In these measurements, an omnidirectional biconical antenna is used as transmitter and a steerable directional horn antenna is used as receiver. The directional and omnidirectional path loss exponents, shadow factors, cross-polarization discrimination ratios and root-mean-square delay spreads are analyzed for both line-of-sight and non-line-of-sight scenarios in both co-polarization and cross-polarization, and these characteristics are compared for different frequencies and environments. It is found obvious depolarization phenomenon in non-line-of-sight scenario for higher frequency. Compared to the corridor, the stairwell has larger path loss exponents and root-mean-square delay spreads, and the depolarization is also more evident in stairwell. The results in this paper are beneficial to building efficient and robust indoor mmWave communication systems.

A Low-Profile Hybrid-Fed Dual-Polarized Antenna with High Isolation and High Cross-Polar Discrimination

This work presents a wideband hybrid-fed ±45o linear dual-polarized patch antenna design for sub- 6 GHz 5G base stations. Two polarizations are created by a slot-coupling with rectangular H-slot (+45) and a capacitive coupling with modified L-probe (−45). Antenna exhibits wideband −10 dB impedance bandwidths of 40.7% and 35.6% for slot-fed and probe-fed ports, respectively. Due to the special design of suspended stacked patches with hybrid-fed excitations, high port isolation ( 38 dB) are achieved. Symmetric and directional radiation patterns with stable gain are obtained in E and H planes for each polarization. Compared to its bandwidth, antenna is low-profile (10.6 mm) with front-to-back ratio greater than 22 dB. Simulations and experimental results are reported and discussed.

Design of Wideband Linearly Polarized 3-Bit Transmit-Array Antenna With Polarization Rotation Unit Cell

The millimeter-wave (mm-wave) band is expected to be the optimal solution for future wireless communication systems as it provides a wide bandwidth, which enhancing data transmission rate. Therefore, high-directive antennas, principal elements for mm-wave wireless communications, are used at the mm-wave band as they can overcome the negative effect of high path losses. A transmit-array antenna (TA) operates at the mm-wave band (around 28 GHz) with high aperture efficiency, high gain, wide bandwidth, and low-profile TA surface has been designed. Basically, the aperture efficiency of the TA depends on the unit cell (UC) characteristics, and feed antenna radiation pattern. Therefore, the UC elements designed based on capacitive differential feeding and true time delay techniques, as a result the designed UC has a wide bandwidth with a stable broadside radiation pattern, high cross-polarization discrimination and a full phase range (0-360°) and a maximum element loss of 0.5 dB. Moreover, the designed UC rotates the polarization of linearly polarized electromagnetic (EM) wave to its orthogonal direction with high efficiency, a polarization conversion ratio higher than 0.9 is achieved within the operating frequency band. The used techniques to design the proposed UC have a significant effect on TA antenna performance, in terms of gain and bandwidth. The TA antenna surface and the feeding antenna have been designed and fabricated. The maximum gain is 31.15 dBi. The 1 dB gain bandwidth is 12.7% while the 3 dB gain bandwidth is 21% around 28 GHz. The aperture efficiency is better than 50% and the cross-polarization level is less than -37 dB, on the frequency range from 25 to 31.5 GHz.

Low-Profile Dual-Polarized Isoflux Antennas for Space Applications

Design, realization, and measurements of an X-band antenna for data downlink (DDL) from low Earth orbit (LEO) satellites are presented. This antenna has an isoflux radiation pattern and operates in dual circular polarization with cross-polar discrimination (XPD) higher than 18 dB on the operational bandwidth. Two solutions are first proposed: one realized by a metasurface with circular strips printed on a dielectric slab and another realized by concentric metallic corrugations. Starting from a basic scattering mechanism of a self-complementary ring-type metasurface excited by a perfectly polarized source, both these antennas are designed by optimizing an equivalent anisotropic impedance surface excited by a short hat feed. The corrugated antenna is realized and measured, confirming that the performances are compliant with the requirements for next-generation DDL antennas.

Ultrathin Subterahertz Half-Wave Plate With High Conversion Efficiency Based on Zigzag Metasurface

In this communication, an ultrathin transmissive half-wave plate (HWP) based on a bi-layered zigzag metasurface operating at the lower frequency edge of the terahertz (THz) spectrum is numerically and experimentally studied. The thickness of HWP is only $100~\mu \text{m}$ and less than $\lambda $ /20 at the operation frequency, and it achieves an amplitude transmission efficiency over 90% and a cross-polarization discrimination around 30 dB within a fractional bandwidth near 9%. A detailed analysis of the device robustness with respect to layer misalignments is carried out by designing and fabricating two additional devices with the maximum possible shift between layers along both transverse directions. The results show that the device is extremely robust relative to a misalignment along $x$ and exhibits a frequency shift with misalignments along $y$ , while maintaining in all cases an excellent performance as a HWP. The communication ends with a final study to ascertain a physical mechanism that explains the robustness of the device in regard to misalignments. These results complement and extend the reach of metasurfaces in the emerging THz band.

High Isolation and Low Cross-Polarization of Low-Profile Dual-Polarized Antennas via Metasurface Mode Optimization

A low-profile dual-polarized metasurface antenna with high isolation and low cross-polarization is proposed in this communication. The proposed metasurface consists of an array of $4\times 4$ patches. Through characteristic mode analysis (CMA), a pair of degenerate modes is identified to achieve the desired radiation features. By modifying the patches of the metasurface, the strongest mode current distributions of the two modes are moved from the center to the edge of the metasurface. One feed port can efficiently excite only one particular mode, and the other mode cannot be excited simultaneously. Each of the modes are differentially fed using two Y-shaped microstrip lines via two slots. As a result, both high isolation and low cross-polarization can be obtained. The simulation and experimental results show that the proposed antenna achieves not only a low profile of $0.05\lambda _{0}$ (where $\lambda _{0}$ is the free-space wavelength at the center resonant frequency) but also a broad impedance bandwidth of 36% and a high isolation of 53 dB. In particular, the enhanced cross-polarization discrimination (XPD) is lower than −40 dB at the broadside, lower than −33 dB within ±30° of the main lobe, and lower than −28 dB within ±60° of the main lobe.

Experimentally Analyzing Diverse Antenna Placements and Orientations for UAV Communications

A vast array of potential applications is emerging for drones and other devices to collaborate from disaster relief and search and rescue missions to smart agriculture and IoT systems. As drones move across multiple altitudes, they must have the ability to communicate across any direction in a three-dimensional (3D) space. However, due to the heterogeneous nature of the drone body and its interaction with the mounted antennas, different antenna positions on the drone can result in variations in the radiation pattern. While there have been a fair number of airborne communication works, few consider the role that antenna positioning has on the resulting transmission along the azimuth and elevation planes. In this work, we study the effects of the drone body and various antenna placements on the radiation pattern and fading of drone-based channels. Through systematic anechoic chamber and in-field measurements, we show that the drone body alters the radiation pattern of the mounted antennas, rendering the common assumption of a constant azimuth radiation pattern invalid. In addition, the body increases polarization mixing of drone-based channels, resulting in significant degradation of the cross-polarization discrimination (XPD). Hence, we propose using effective radiation pattern and XPD values instead of relying on measurements and/or assumptions that disregard drone-antenna interaction. We then analyze the shadowing and losses associated with the drone body for many antenna setups at various elevation angles and show that when mounted on the opposite side from the ground transmitter, shadowing increases with relatively-higher drone elevations. To account for these body-induced effects, we introduce rotational loss that results in better prediction results of the large-scale fading behavior compared to conventional models that neglect these body effects. Then, we analyze the small-scale fading for various antenna setups and show that the Rician K-factor is strongly dependent on elevation for polarization-matched vertical links, while it is approximately flat for cross-polarized links. To do so, we conduct a set of drone-to-drone (DtD) experiments at high altitudes with no surrounding reflectors and compare results to those obtained by our ground-to-drone (GtD) measurements. We find that, while at low elevations the ground can reduce the K-factor by 10 dB, at higher elevations, small-scale fading is dominated by the antennas, not the ground.

High port‐to‐port isolation dual circularly polarised microstrip patch antenna with multifunction DGS

A two-port planar dual circularly polarised microstrip patch antenna is presented. The designed antenna has two groups of patches, each for transmission and reception. In one such group, only the central patch with truncated opposite corners is probe-fed whereas the surrounding patches act as parasitic patches for bandwidth and gain enhancement. A defected ground structure (DGS) consisting 4 units of complementary square spiral resonators is used to enhance the port-to-port isolation as well as the axial ratio (AR) bandwidth. Based on the measured data of the fabricated prototype, the antenna is seen to have an impedance bandwidth of 900 MHz with the centre frequency of . Moreover, the AR bandwidth is measured to be 600 MHz at , whereas the peak gain within this band is found to be ranging from 6.8 to 7.9 dBic. It is also noted that the AR bandwidth lies entirely within the impedance bandwidth and the cross-polarisation discrimination is 20 dB in the boresight direction.

Wideband and Low Cross-Polarization Transmitarray Using 1 Bit Magnetoelectric Dipole Elements

The application of magnetoelectric (ME) dipole to achieve wideband and low cross-polarization transmitarray design is presented in this article. First, a novel meandering-probe-fed ME dipole that exhibits a wideband matching, central feeding configuration, and symmetrical antenna structure is developed. These preferred features are borrowed to address the narrowband and potential element-displacement issues in 1 bit transmitarray element design. Numerical simulations of the proposed 1 bit ME-dipole transmitarray element show a wide 1 dB insertion-loss bandwidth of 47% and a low cross-polarization level of −40 dB. Measured results of the transmitarray designed using the proposed ME-dipole elements indicate an operating bandwidth of 47% and a cross-polarization discrimination (XPD) around 35 dB. In addition, a dual-layer phase compensation scheme for cross-polarization synthesis is described. The effectiveness of this method is demonstrated with a cross-polarization cancelation scheme that further improves the measured XPD to 40 dB. The proposed transmitarrays show advantages of remarkable bandwidth, low cross-polarization, and comparatively high aperture efficiency over most reported 1 bit designs.

Low‐profile dual‐polarised metasurface‐enabled antenna array for base‐station applications

This Letter presents a dual linearly polarised microstrip antenna for base station applications. Firstly, a dual-polarised metasurface-based antenna element employing differential feeding technology is proposed. The proposed antenna element achieves a simulated bandwidth of 11.6% for |S 11 | < −15 dB, mutual coupling better than 30 dB, and the cross-polarisation discrimination level over 35 dB. Secondly, based on the antenna element, a 3 × 3 antenna array is eventually presented, which was fabricated and characterised. The measured bandwidth is 12% for |S 11 | < −10 dB, and the port-isolation is over 25 dB. The superiorities of low-profile and high port isolation indicate that the proposed design is a promising candidate for sub-6G base-station applications.

A Broadband Low-Profile Dual-Linearly Polarized Dipole-Driven Metasurface Antenna

A low-profile broadband metasurface antenna (MSA) with dual-linear polarization is developed. The developed MSA mainly consists of a 4 × 4 grid-slotted patch array, two pairs of orthogonally printed feeding dipole strips, two vertically grounded and orthogonally placed microstrip Γ-shaped feeding structures, and an intact ground plane. It is demonstrated that the strip-excited MSA excites a leaky wave mode, a surface wave mode, and a dipole mode to provide a wide operational bandwidth. The prototype, with an overall size of 0.65 λ0 × 0.65 λ0 × 0.07 λ0 (λ0 is the wavelength in free space at the center operating frequency) was fabricated and measured. Three modes with broadside radiation patterns for each port are simultaneously excited to create a wide impedance bandwidth 36% with the average gain value 9.3 dBi. Moreover, the port-to-port isolation and the cross-polarization discrimination (XPD) are, respectively, higher than 26 and 25 dB.

Millimeter-Wave Dual-Polarized Differentially Fed 2-D Multibeam Patch Antenna Array

In this article, a novel millimeter-wave dual-polarized 2-D multibeam antenna array incorporating differentially fed antenna elements is proposed to achieve high cross-polarization discrimination (XPD) when the beams scan to the maximal pointing angles. The antenna element is composed of an SIW cavity with four shorted patches placed inside, and it is differentially excited for dual-polarization by a pair of feeding strips and transverse slots beneath the patches. Differential excitation is realized by a power divider designed on two laminate layers. Two Butler matrices placed perpendicularly with each other in different laminates are employed to generate four tilted beams with dual-polarization. A $2\times 2$ dual-polarized 2-D multibeam antenna array working at 28 GHz is designed, fabricated, and measured. The operation bandwidth of the antenna is 26.8–29.2 GHz. The improvement in the XPD is experimentally demonstrated by far-field measurement. When the beams scan to 30° off the boresight, the measured XPDs are 28 dB at the center frequency and higher than 25 dB over the operation bandwidth, which confirms that the cross-polarized radiation in the 2-D multibeam antenna array is suppressed by using the differential-feeding technique. The measured gain is in the range from 7.6 to 10.5 dBi.

Implementation of Single Band Dual-Polarized for Satellite Communication using MISO System

MISO (Multiple-Input Single-Output) similar architecture of most terrestrial wireless network networks instead of more and more scientists striving to apply MISO technology to satellite technology, it can be used to achieve a lower rate of application bit error and risk of complications, while managing increased power boost technology. In mitigating the phenomenon increasingly crowded networks, sites, and increasingly strained sources and frequency of orbital interacting. That channel electricity, bit error rate, and single-band dual-polarized probabilities of MISO outage communication systems are evaluated in the paper. In the first step, when the XPD (Cross-Polarization Discrimination) antenna in a certain organism is greater than 1. With the XPD change, the channel throughput increases in scale linearly. Second, under BPSK modulation, it analyses the bit error rate BER of the specification. The design incorporates a sufficiently low (BER) when the SNR is substantial; analysis of the frequency of outage of a distributed MISO system demonstrated when the signal to noise ratio (SNR) is massive, the handset would maintain the prospect of an outage low enough. Assessment of the spectral range of satellite communication, in the analysis process, the criteria of the rice channel are applied to the channel, review excluding certain traits of the dual-polarized satellite MISO. The public would provide great feedback for the productivity of the future of MISO satellite technology. In a previous paper, the author designed a channel modeling dual-band for satellite communication using the MIMO technique. Using this technique, the system cannot achieve greater performance and at the same time using a dual-band will decrease the system's capability. To decrease the above issues, the paper introduces a new method called the MISO system. Using the MISO technique, the system can gain high performance and the system will get greater bandwidth, BER, and SNR. The advantage of using single-band dual-polarized is, uplink and a downlink frequency of the satellite can be calculated very easily and accurately.

A Dual-Polarized Planar Antenna Array Differentially-Fed by Orthomode Transducer

This article presents a new design of a differentially fed substrate integrated planar antenna array with dual-polarization. Compared with the traditional dual-polarized antenna arrays, the proposed array antenna has the advantages of simple configuration, high cross-polarization discrimination (XPD), and high gain. The 2×2-element subarray design with a via-loaded crossover structure is used, which reduces the complexity of the array antenna. The operation bandwidth is improved by generating three resonances in the subarray. An 8×8 antenna array is designed, prototyped, and tested to exemplify its potential applications in large dual-polarized antenna arrays. A planar orthomode transducer is used to achieve differential excitation for the antenna array. The measured results show that the proposed antenna array has an impedance bandwidth of 19.2-20.7 GHz for |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB and port isolation higher than 20 dB. The array antenna exhibits a high XPD of 43 dB and a flat gain of about 22.2 dBi within the bandwidth.

Broadband Dual-Polarized Loop Cross-Dipole Antenna for 5G Base Station Applications

A broadband dual-polarized base station antenna is proposed in this paper. The antenna consists of loop cross-dipoles, Y-shaped coupling feeding lines, and a metal box reflector. An equivalent circuit model including a signal flow diagram is established to analyze the mechanism of the proposed antenna in detail. Moreover, the Y-shaped coupling feeding lines are introduced to control the coupling with the antenna to achieve broadband and good impedance matching. The prototype of the antenna is fabricated and measured. The measured results show that the antenna with simple structures can operate at the band of 3.2–5.22 GHz (48%) with high port-to-port isolation (35 dB) and stable gain (9 ± 1 dBi). The measured results show good agreement with simulated results, especially in cross-polarization discrimination ratio (&gt;27 dB) and the half power beam width (61° ± 3° at the E-plane, 68° ± 3° at the H-plane). In summary, the proposed antenna could be a good candidate for 5G sub-6 GHz base station applications.

A Bandwidth-Enhanced Cavity-Backed Slot Array Antenna for mmWave Fixed-Beam Applications

A bandwidth-enhanced $8\times 8$ cavity-backed slot array antenna for fixed beam applications is presented. The antenna consists of four $2\times 2$ subarrays fed by ridge gap waveguide and a modified bow-tie coupling slot in the cavity layer. The proposed bow-tie coupling slot provides additional $\text{10}\%$ impedance bandwidth as compared to the traditional rectangular coupling slot. The fabricated prototype demonstrates an $|S_{11}|\leq -10\,$ dB fractional impedance bandwidth and a $3\,$ dB gain-drop bandwidth of approximately $\text{28}\%$ and $\text{25}\%$ , respectively, with peak gain of $26.4\,$ dBi, aperture efficiency $>\text{60}\%$ and cross-polar discrimination $>40\,$ dB. Measurements show good agreement with simulations. Moreover, we show the impact of the dimensions and shape of the cavity coupling slot on the bandwidth enhancement. The bandwidth enhancement is explained by the double-ridge slot behavior of the bow-tie coupling slot, which shows a more wideband behavior than the traditional rectangular coupling slot behaving like a cross section of a waveguide.

Rectangular DRA Array for 24 GHz ISM-Band Applications

A planar array antenna consisting of 6 units of rectangular dielectric resonators fed by means of novel microstrip lines through aperture coupling is presented. The structure is designed in such a way that two different modes are excited in the array elements that yield a high bandwidth and gain. Based on the experimental results, the antenna is seen to have an impedance bandwidth of 6.98% centered at 24.09 GHz. Furthermore, the antenna gain is seen to lie between 7 and 9.5 dBi within its entire bandwidth, whereas the cross-polarization discrimination is better than 45 dB in the boresight. These features, along with its low-profile structure, make this antenna a suitable candidate for usage in short-range radars, wireless sensor nodes, and other sensors for the 24 GHz Industrial, Scientific, and Medical (ISM) band.

Experimental Study on the Impact of Antenna Characteristics on Non-Stationary V2I Channel Parameters in Tunnels

This paper analyses the experimentally-assessed dual-polarized (DP) mobile channel in a tunnel environment at 1.35 GHz under traffic conditions. We investigate the impact of antenna polarization and radiation pattern on the non-stationary vehicle-to-infrastructure (V2I) channel. Basic channel evaluation metrics are examined including path gain, co-polarization ratio (CPR), and cross-polarization discrimination (XPD). In addition, the stationarity region is estimated using the channel correlation function approach, and used to calculate the time-varying delay and Doppler power profiles. Statistical models are presented for parameters like CPR, XPD, RMS delay and Doppler spreads, where the lognormal distribution provides the best fit. The polarization and the opening angle of the antennas into the propagation channel are found to strongly influence the observed non-stationarity of the channel. They impact the degree of multipath richness that is captured, thus providing different path gain, delay and Doppler spreads. Based on our analysis, the directional antenna with vertical polarization provides the longest stationarity time of 400 ms at 90 km/h, as well as the highest path gain and lowest dispersion. Furthermore, the DP channel capacity is calculated and its dependence on different normalization approaches is investigated. We propose a more accurate normalization for the DP channels that takes the conservation of energy into account. Moreover, the subchannels correlation coefficients are determined. While the condition number is found to be low on average, the correlation results show high correlation among the DP subchannels. As conclusion, we show how the CPR and XPD play the main role in providing multiplexing gain for DP tunnel channels.