Cross-polarization Level Research Articles

A Low-Profile, Triple-Band, and Wideband Antenna Using Dual-Band AMC.

When a wideband antenna is backed by an artificial magnetic conductor (AMC) reflector, the bandwidth is reduced. With the optimization of the shape of the AMC it is possible to exhibit multiband behavior, but the problem becomes complex if the bands are also intended to be wide. In this study, a methodology that exploits both the expected in-band and out-of-band behaviors of a dual-band AMC was used to design a low-profile, triple-band, and wideband directive antenna. The methodology was validated with a prototype suitable for the European standards of 4G/5G and Wi-Fi 2.4/5/6E, operating within the following bands: 2.4-2.7 GHz, 3.4-3.8 GHz, and 5.17-6.45 GHz. The measured results showed respective peak values of 8.0, 9.1, and 10.5 dBi for the broadside realized gain, front-to-back ratios larger than 19 dB, cross-polarized levels lower than -18 dB, and stable half-power beamwidths within each band. Furthermore, 3 dB gain bandwidths of 34.4%, 19.7%, and 31.0% were also measured.

A Single-Layered Broadband Reflectarray Employing 0.15-Wavelength Elements

A single-layered broadband reflectarray antenna employing 0.15-wavelength elements is proposed and investigated in this letter. The unit cell is constituted by a ring patch inserted with an interior concave arm and arranged in a grid size of 4.5 mm × 4.5 mm, corresponding to only 0.15 wavelength at 10 GHz. Despite such a small grid spacing, a linear phase close to 360° can still be obtained by changing the height of the embedded concave arm, without adjusting the external ring size. A planar reflectarray antenna composed of 2116 unit cells is designed, manufactured, and tested. According to the measured results, the 1 dB gain bandwidth of the reflectarray antenna is 29%, while the peak aperture efficiency is 66%. Besides, satisfactory sidelobe and cross-polarization levels are also achieved. These promising features show a good overall performance of the proposed array and also successfully demonstrate the feasibility of employing 0.15-wavelength element for wideband reflectarray designs.

Closely-Spaced Half-Ring Patch Antenna Pair With Enhanced Isolation, Reduced Cross Polarization, and Consistent Beam

This letter proposes a copolarized and closely-spaced half-ring patch antenna pair (HRPAP) with loading of stubs and shorting pins for isolation enhancement and cross-polarization reduction. By inserting two stubs and adjusting gaps between the HRPAP, consistent resonant frequency, and equal quality factor of the odd and even modes can be simultaneously obtained, which contributes to high isolation of the HRPAP over a wide frequency range. Furthermore, four shorting pins are elaborately loaded so as to weaken the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> -oriented current component of the HRPAP, by which the cross-polarization level in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -plane is significantly reduced. Finally, the proposed HRPAP is fabricated and measured. Both the simulated and experimental results show that the antenna has achieved an isolation level over 30 dB, cross-polarization reduction of about 8.8 dB, and consistent radiation patterns.

Analysis of Cross-Polarized Field by Panel Misalignment Errors in a Deployable Reflector Antenna

This paper analyzes the generation mechanism of a cross-polarized field resulting from panel misalignment errors in a solid-surface deployable antenna. Misalignment of the panel in a deployable antenna results in path length error and rotation of the unit normal vector on the reflector surface. However, in terms of the analysis of cross-polarization (cross-pol) generation, rotational error is a more significant factor. In the aperture field, the distributions of cross-pol components are calculated to identify the polarization characteristics of the radiated field. For uniform misalignment, the peak-to-cross polarization (XPOL) is found to be smaller than -50 dB for misalignment angles less than 3°. Furthermore, when the panels are non-uniformly misaligned with a sinusoidal distribution, the cross-pol level depends on the angular position of the maximum misalignment.

A Single-Layer Circularly Polarized Reflectarray Antenna with High Aperture Efficiency for Microwave Power Transmission

In this article, a single-layer circularly polarized reflectarray antenna (RA) with a linearly polarized feed is proposed for microwave power transmission. The unit cell of the reflectarray is composed of a rectangular patch surrounded by four groups of E-shaped structures, which feature a very low level of cross-polarization. Simulation results demonstrate that the phase of its reflection coefficient can be tuned continuously in a range of 500° by adjusting the lengths of the E-shaped structures. In response to a normally incident plane wave, the phase values of the reflection coefficient associated with two orthogonal linear polarization directions of the reflected wave can be tuned independently, which makes it possible to convert a linearly polarized incident wave to a circularly polarized beam. A reflectarray with 15 × 15 unit cells is fabricated and tested. The measurement results demonstrate a 3-dB axial ratio bandwidth of more than 2 GHz around the center frequency of 5.8 GHz. The measured gain value of the fabricated reflectarray is 25.4 dBi, corresponding to an aperture efficiency of 52.5%.

A Half-Mode Cavity Backed Hybrid Array Antenna Using Substrate Integrated Waveguide (SIW) Technology

This article proposes a hybrid array antenna where a cavity-backed antenna is used jointly with a patch antenna using half-mode substrate integrated waveguide technology (HMSIW) to reduce antenna size. This hybrid structure consists of a flexible Rogers RO4003C substrate ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\epsilon_{{r}} =3.55$ </tex-math></inline-formula> ) showing linearly polarized TE101 mode where the cross-polarization level (XPL) is less than −12 dBi. An inset feed has been utilized to excite the main cavity resonator, and later by proximity coupling, the parasitic patch is also excited in TE101 mode. By further dividing the outer patch, four new cases of antenna have emerged, and comprehensive investigations on their parameters based on simulation have been presented. It paints an upgrade of the antenna’s performance. As per simulations, further dividing of the patch helps to bring out positive changes in the antenna’s performance by escalating gain, bandwidth (BW), and efficiencies while also lessening XPL, sidelobe levels (SLLs), and associated loss up to a satisfying level. The proposed antenna is then fabricated and experimentally validated in its theoretical analysis. A couple of experimentally validated parameters make this fabricated sample suitable for wireless application and maintain good agreement with numerical simulation. CST Microwave Studio and HFSS carried out the associated numerical simulation.

Design of micro-strip patch antenna for C – band applications

This paper presents the design of a horizontal slot micro-strip Patch antenna with a dual slot inset feed mechanism. The antenna is resonating at 4.28 GHz, with reflection coefficient of -16.32 dB, and a Bandwidth of 1 GHz. Rogers RT580 dielectric is used as substrate having relative permittivity of 2.2 and tan δ value of 0.0009. The gain of the antenna is 6.46 dBi and the cross-polarization levels are reduced to -16.4 dB. The micro-strip antenna can be used for C Band applications such as satellite communication between ground station and satellite.

Hexagonal-Triangular Combinatorial Structure Based Dual-Band Circularly Polarized Patch Antenna for GAGAN Receivers

A multilayer gap-coupled dual band hexagonal microstrip patch antenna is presented for GPS Aided GEO Augmented Navigation (GAGAN) receivers. GAGAN is developed by AAI (Airport Authority of India) and ISRO (Indian Space Research Organization) exclusively for aviation purposes with the GPS frequencies L5 (1176.45 MHz) and L1 (1575.42 MHz). The proposed GAGAN antenna has three trapezoidal and four equilateral triangular patch resonators configured to form a gap-coupled hexagonal patch on the top layer and seven equilateral triangular patches with slots in between to form the middle layer. Both the layers are fed by a single coax feed to achieve a dual band compact microstrip antenna of size 55 mm x 55 mm x 3.2 mm. Instead of designing the hexagonal antenna conventionally from a circular patch antenna, the sides of the equilateral triangular patch are truncated to obtain the proposed compact hexagonal antenna as the triangular antenna occupies less area when compared to circular or square patches for a fixed frequency. To bring in novelty with improved performance, the combinatorial structured configuration has been explored through step-by-step optimization. The aspects of GAGAN requirements like circular polarization with a single input, dual band operation and high gain with gain flatness are achieved with this compact structured antenna when compared to square and circular patch antennas. The combinatorial structures such as perturbation and truncation introduced in the patches are responsible for exciting two near-degenerate orthogonal modes producing circular polarization (CP). A cross slot etched in the center patch results in gain enhancement with a gain above 3.2 dBi over a bandwidth of 20 MHz in both the bands. Five shorting pins are added to achieve high impedance matching and good CP with an axial ratio (AR) below 2 dB. The simulated and measured results are found to be in good agreement with greater than 20 MHz operational bandwidth exhibiting CP with an omni-directional radiation pattern having high cross polar levels of -22 dB. The size reduction achieved in the proposed design is 56.79% when compared to the conventional hexagonal patch antenna. The measured 10 dB impedance bandwidth is 2.7% and 2.1% for L5 and L1 bands respectively with a 3 dB AR bandwidth of 2.3% for L5 and 2.0% for L1, satisfying GAGAN requirements.

Wideband Substrate Integrated Cavity-Backed Dielectric Resonator Antenna at Sub-6-GHz Band

The design and implementation of a wideband single-mode dielectric resonator antenna (DRA) with a substrate integrated cavity-backed structure is presented in this paper. Two short-circuited striplines with differential feeding are placed inside the substrate integrated cavity (SIC) for pure mode excitation of the DRA, providing stable radiation characteristics, and low cross polarization levels. The cavity is coupled to the cylindrical DRA through an annular slot. The fundamental <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 of the DRA is excited over a wide frequency band, as a result of the similar field distribution created on the coupling annular slot by two modes inside the cavity. Measurement results show a maximum gain of 8.2 dBi at 5.45 GHz. The gain is 7.8 dBi at the center frequency of 5.15 GHz and its 1-dB bandwidth is 23%. The measured 10-dB return loss bandwidth is 26% (centered at 5.15 GHz) which is the highest among the previously reported works based on cavity-backed DRAs and single-mode excited DRAs. The measured co-polarization and cross-polarization gain difference at the boresight direction is more than 26 dB. This antenna element can be used to cover a wide range of wireless standards in wireless access point and applications due to its stable wide band performance.

Design, Modeling and Analysis of Low Cross Polarization Level Low Radar Cross Section Conformal Ultra Wideband Absorber based on Resistive Metasurface

Design, Modeling and Analysis of Low Cross Polarization Level Low Radar Cross Section Conformal Ultra Wideband Absorber based on Resistive Metasurface

Wideband and Dual-Polarized Crossed Dipole Antenna Design Using Substrate-Integrated Coax

A wideband and dual-polarized dipole antenna design technique is presented. The proposed antenna employs two sets of dipole elements in orthogonal configuration and separated by a dielectric layer. The dipole elements are excited with two separate substrate-integrated-coaxial feeds to achieve high port-to-port isolation and the overall antenna stackup is enclosed in a substrate-integrated-waveguide (SIW) cavity. To validate the proposed substrate-integrated-coaxial fed dual-polarized antenna design method, a prototype antenna was fabricated using standard multilayer printed circuit board (PCB) manufacturing technologies to operate in the Ku-band. The measured and simulated results exhibit that the designed antenna has a wide impedance bandwidth of less than -10dB reflection coefficients at 10.28-14.8GHz and the port-to-port isolation between the two orthogonally polarized dipole antenna ports is greater than 20dB at most frequencies, making it suitable for many applications such as satellite communications. The antenna has a relatively stable gain pattern with a gain value of 5.5-6.5dBi and a low cross-polarization level (<16dB) over the operating frequency range.

Compact Shared-Aperture Dual-Band Dual-Circularly-Polarized Waveguide Antenna Array Operating at K/Ka-Band

In this article, a compact shared-aperture dual-band dual-circularly polarized waveguide antenna array is presented to achieve high gain and wide bandwidth in full-duplex satellite communication at K/Ka-band. The designed antenna array can simultaneously operate at 20 GHz band with right-hand circular polarization (RHCP) radiation and 30 GHz band with left-hand circular polarization (LHCP) radiation. The array is composed of circular polarization (CP) waveguide antenna elements and full-corporate feed networks. The ridged spectrum polarizer is inserted in the square waveguide to form CP radiation in a stepped waveguide antenna element. The sequential rotation technique is adopted in feed networks to further improve CP axial ratio (AR) performance and bandwidth. The prototype of the proposed 4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times4$ </tex-math></inline-formula> antenna array is fabricated and measured for demonstration. Experimental results show that the overlapped bandwidth in terms of reflection coefficients less than −10 dB and AR lower than 2 dB is 18–22 GHz for RHCP radiation in K-band, and the corresponding bandwidth for LHCP radiation in Ka-band is 28–32 GHz. The measured cross-polarization levels are better than 25.82 dB at 20 GHz and 20.25 dB at 30 GHz, and the measured peak gains at K/Ka-band are 23.94 and 26.87 dBic, respectively.

A Polarization Reconfigurable 3D Printed Dual Integrated Quadrifilar Helix Antenna Array Embedded Within a Cylindrical Dielectric Mesh

This article presents a polarization reconfigurable dual integrated quadrifilar helix antenna array that is embedded within a cylindrical-shaped mesh of dielectric material. The entire structure is 3-D-printed and equipped with grooves to support the eight radiating elements and accordingly enforce the helical pitch and orientation. The dual antenna array, acting as one, features double fractional bandwidth (i.e., 30%) while exhibiting polarization reconfigurability by switching between left-handed and right-handed circular polarization states. More specifically, the proposed structure operates over the span of frequencies between 1.7 and 2.3 GHz while ensuring a circularly polarized behavior. The polarization reconfigurability is obtained by changing the phase excitation of the eight helical arms. Accordingly, a dedicated feeding network is proposed to achieve the required phase reconfiguration. A prototype is fabricated and tested as a proof of concept, where the measured results agree well with the simulated data. The 3-D-printed fabricated prototype reconfigures its circularly polarized behavior over the entire operating bandwidth with a maximum measured realized gain of 6.4 dBic, an axial ratio that varies between 0.5 and 2.5 dB, and cross-polarization levels of at least 20 dB along the direction of maximum radiation.

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 Low-Profile Dual-Polarized Magneto-Electric Dipole Antenna for 5G Applications

A low-profile dual-polarized magneto-electric dipole (MED) is presented in this communication. The low profile was achieved using meander slots on the vertical magneto dipole, reducing the antenna height to 0.15λ0, where λ0 is the wavelength of the center frequency. Relatively, the proposed MED structure is easier to process and more stable than the traditional low-profile MED structure. The broadband performance for 5G Applications was realized based on MED structure, and the dual-polarization structure has wider coverage area and lower multipath transmission losses. Moreover, the orthogonal feeding structure provides a satisfying isolation between two ports. To verify the simulation results, a prototype of the proposed antenna was fabricated and measured. The results show that the overlapped operating frequency bandwidth with |S11| ≤ −10 dB, |S12| ≤ −20 dB was 36.8% from 3.1 GHz to 4.5 GHz, the peak gain reached 10.2 dBi, and the average gain exceeded 8.5 dBi. The measured 3 dB beamwidth with more than 44 degrees beamwidth was realized in both E-plane and H-plane. In addition, cross-polarization levels below −22 dB that covered the above frequency band were achieved. Compared with other MED antennas, in addition to broadband and high gain, the proposed antenna has the advantages of a low profile, easy processing, and low cost, which make it a competitive candidate for 5G applications.

A 3D-Printed DRA Shared-Aperture Array for Low Cost Millimeter-Wave Applications

In this article, a K-/Ka-band shared-aperture array with high isolation is proposed using 3D-printed dielectric resonator antennas (DRAs). The design procedure with DRAs enables flexibility while implementing shared-aperture arrays. Furthermore, DRAs as nonmetallic radiators are attractive for millimeter-wave (mm-wave) applications due to the absence of ohmic loss. In addition, 3D-printing technology facilitates the design of complex shapes with high-dimensional accuracy. The K- and Ka-bands DRAs are orthogonally oriented to provide improved isolation and cross-polarization level. Meanwhile, the corresponding feeding networks are implemented using the substrate integrated coaxial line (SICL) and the substrate integrated waveguide (SIW). Thus, further isolation improvement is provided by using two different feeding mechanisms for the K- and Ka-bands radiators. Moreover, the SICL network is shared with the SIW wall to efficiently utilize the feeding aperture. As a proof-of-concept, the 3D-printed shared DRAs are designed and fabricated. The standard printed circuit board (PCB) technology is used for the fabrication of the antenna boards. The measurement data agree with the simulations, realizing high isolation and cross-polarization level. The proposed array features low profile, ease of integration, and wideband operation, which makes it viable candidate for mm-wave applications.

Design and Implementation of Ku-Band High Directionality Antenna

In this article, a Ku-band high directivity antenna is designed, which consists of a radiation waveguide section, a mode conversion section, and a coaxial waveguide conversion section. In this article, the theoretical calculation process of antenna components is summarized and supplemented. The calculation method between key technical indexes and structural parameters is established. The key technical parameters of the antenna, including input return loss, half-power beamwidth, gain, and cross-polarization level, are studied and explored. The radiation performance of the antenna can be further improved by optimizing the structural parameters. Finite-element analysis and COMSOL simulation software are used to study. In order to reduce antenna reflection, a method of equal-Q impedance transformation is proposed for rectangular and circular waveguide converters and coaxial waveguide converters. Finally, the proposed feed antenna is processed and verified, and the measured results are in good agreement with the simulation results.

Broadband Cross-Slotted Patch Antenna for 5G Millimeter-Wave Applications Based on Characteristic Mode Analysis

This article proposes a wideband differentially fed dual-polarized magnetoelectric (ME) dipole for millimeter-wave (mm-Wave) applications. Various electric and magnetic characteristic modes of a slotted patch antenna are investigated and utilized effectively to create a stable broadside radiation pattern, covering fifth-generation (5G) frequency bands from 24.25 to 40 GHz. To implement this, the lifted ground (LGND) concept is applied to achieve a 57.1% impedance bandwidth for a single antenna element. In addition, the three resonances of the antenna can be manipulated independently. The use of differential feeding allows more than 36 dB of port-to-port isolation across the entire operating band. The measured gains of the single element and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times $ </tex-math></inline-formula> 2 array are 8.4 and 13.4 dBi, respectively. Also, the measured results indicate symmetrical E- and H-plane radiation patterns and cross-polarization levels lower than −26 dB. With the favorable electrical performance, compact size, simple structure, and low-cost fabrication, the proposed ME dipole is a promising candidate for mm-Wave Antenna-in-Package (AiP) applications.

A One-bit Transmit Phased Array with Spatial Excitation for Sub-6 GHz Wireless Systems

Introduction. Due to the increasing number of users, growing rates of data transmission, and rapid advancement of the Internet of Things, the parameter of channel capacity is acquiring greater importance in modern communication systems. In wireless communication systems, capacity limitation occurs due to a low signal-to-noise ratio, one reason for which consists in high losses associated with the propagation of electromagnetic waves. These losses can be compensated using high-gain antenna systems, such as metasurfaces, transmitarrays, or reflectarrays.Aim. Development and research of a one-bit transmit phased antenna array with spatial excitation for use in wireless communication networks across sub-6 GHz frequencies. The issues of reducing the insertion losses associated with the cell geometry and control components are discussed. Account is taken of the parasitic parameters of p–i–ndiodes used as control elements for phase adjustment in a unit cell. Methods for suppressing cross-polarization in a unit cell with the purpose of reducing insertion losses are studied.Materials and methods. The characteristics of unit cells in a transmit antenna array were studied by numerical electrodynamic modeling in the CST Microwave Studio computer-aided design system. The obtained results were confirmed by an experimental study of samples.Results. A unique design of a unit cell comprising the main element of a transmitarray was proposed. On its basis, a transmitarray was designed and manufactured, whose measurements proved the level of insertion losses to be lower than 1.5 dB in the operating frequency band of 210 MHz (3.6 %). The level of cross-polarization was found to be lower than 24 dB, and the gain attenuation did not exceed 2.5 dB in the range of beam deflection from 45° to -45°.Conclusion. The design simplicity, low losses, and acceptable cross-polarization levels of the developed one-bit transmit phased antenna array with spatial excitation confirm its feasibility for modern communication systems.

A Wideband Folded Dipole Antenna with an Improved Cross-Polarization Level for Millimeter-Wave Applications

A low-profile planar millimeter-wave (MMW) folded dipole antenna fed by substrate integrated waveguide (SIW) is proposed in this letter. By etching the gaps at the proper position of 1.5λ dipole, an additional resonant mode is generated. Accordingly, the working bandwidth is greatly broadened. In addition, by appropriately adjusting the length of the dual-side parallel strip line (DSPSL), the radiated electric fields generated by the aperture of the feeding SIW and the connecting metallic vias of the folded dipole are designed with an out-of-phase potential. Hence, the cross-polarization of the presented folded dipole antenna is improved as well. As a demonstration, a prototype is fabricated and measured. The experimental results exhibit that the proposed folded dipole has a −10 dB impedance bandwidth of 58.5% (from 30.3 GHz to 53.7 GHz), a gain of around 5 dBi with more than 120 degrees beamwidth in H-plane, and a cross-polarization levels below −15 dB, covering the working frequency band. Compared with the up-to-date planar dipole antenna, the proposed folded dipole achieves the widest working bandwidth and low cross-polarization level. The proposed antenna can be used as the terminal antenna of the MMW communication system.