Polarized Antenna Array Research Articles

Antena Susun Berpolarisasi Sirkular dengan Menggunakan Distribusi Daya Dolph Tschebycheff (Circularly Polarized Array Antenna Using Dolph Tschebycheff Power Distribution)

This paper discusses the design and realization of circularly polarized array antenna using Dolph Tschebycheff power distribution. The advantages of implementing circular polarization yield the array antenna suitable for outdoor communication system and can minimize the Faraday effect. The Dolph Tschebycheff power distribution is used to suppress the side lobe of array antenna. The proposed array antenna, which is intended to operate at the frequency of 5.3 GHz, consists of five square patch elements with seven diagonal slots upon each element to enhance the bandwidth and to produce the circular polarization. The array antenna is designed and realized using two layers of FR-4 epoxy dielectric substrate with the dimension of 119 mm × 44.1 mm and the thickness of 0.8 mm for each dielectric substrate. Each patch element is fed using a proximity coupling technique excited through a 50 Ω SMA connector. The measurement results show the bandwidth of 720 MHz, the side lobe level of 12.39 dB, the gain of more than 6 dBi around the frequency of 5.3 GHz, and the 3 dB axial ratio bandwidth of 200 MHz. It seems that the realized array antenna could produce wide bandwidth, low side lobe level, and circular polarization, so that it is suitable for WLAN application.

Analysis and design of novel wideband and high efficiency millimeter-wave antenna arrays for 60-GHz applications

A type of millimeter-wave antenna array with flexible design is proposed for a variety of applications at 60 GHz. The antenna array can be adjusted to be linearly or circularly polarized by simply changing the radiation part of the antenna array. High gain, wideband, and high radiation efficiency characteristics can be achieved by adopting a low insertion loss feeding network and broadband antenna elements. For the linearly polarized antenna array, simulation results show that the impedance bandwidth of the 2×2 antenna subarray reaches 21.6%, while the maximum gain achieves 15.1 dBi and has a fluctuation of less than 0.4 dBi within the working bandwidth. Simulation results of the 8×8 linearly polarized antenna array show a bandwidth of 21.6% and a gain of (26.1±1) dBi with an antenna efficiency of more than 80%. For the 8×8 circularly polarized antenna array, simulation results show that an impedance bandwidth of 18.2% and an axial ratio (AR) bandwidth of 13.3% are obtained. Gain and efficiency of up to 27.6 dBi and 80% are achieved, respectively. A prototype of antenna array is fabricated, and results are compared and analyzed.

Simulation and Calculation of Sum Beam Feeding Phase in 8-Element Sequential Rotating Circularly Polarized Antenna Array

Abstract The beam forming network is a key component of the realization and difference function of the single-pulse antenna array. Obtaining the amplitude and phase information of each port of the network is the premise of designing the beam forming network. This paper gives and calculates the feed phase expression of the generated and beam in the 8-element sequential rotating circularly polarized antenna array. The circular polarization components and axial ratio characteristics of the φ=0°, φ=45° and φ=90° planes are calculated by left-hand and port feeding. The results show that the pure circularly polarized wave is obtained in the direction of θ=0° when the φ=0° surface is left-handed and the port is fed. The circular polarization of the antenna is good when the angle is smaller than θ=0°. It shows that the antenna unit obtains a circularly polarized wave after adopting the sequential rotation technique; the circular polarization characteristic on the φ=45° plane and the φ=90° plane is consistent with the φ=0° plane.

8 × 2-Element 60-GHz-Band Circularly Polarized Post-Wall Waveguide Slot Array Antenna Loaded With Dipoles

In this paper, an 8 × 2-element 60-GHz band circularly polarized post-wall waveguide slot array antenna loaded with dipoles is proposed. The antenna is composed of a feeding circuit, radiating slots on radiating waveguides, and dipoles for polarization conversion. By integrating the feeding circuit and the radiating waveguides into a single dielectric layer, the total number of dielectric layers is reduced to two which greatly increases ease of mass production. The feeding circuit divides power into two and feeds the two radiating waveguides from their center. 8 × 2 radiating elements are composed of a slot and a dipole placed on the radiating waveguides. The elements are designed by standing-wave excitation. The antenna is fabricated by printed circuit board technology and its dimensions are 44.5 × 20.0 × 2.16 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The measured results show a 2.1-dB axial ratio, 15.6-dBi gain, and 57.2% efficiency at 61.5 GHz. The proposed antenna realizes a circular polarized array antenna with the minimum number of dielectric layers and electric performance comparable to conventional antennas.

Challenges and Limitations of the Cross-Polarization Suppression in Dual-Polarization Antenna Arrays Using Identical Subarrays

In this article, challenges and limitations of using cross-polarization suppression methods for dual-linear polarization antenna arrays are presented. A simple probe-fed patch antenna and high-performance, dual-polarized hybrid-fed patch antennas are used for this article. The image feed method is used for improving the cross-polarization level and increasing the geometrical symmetry of a very large phased array antenna. It is shown that decomposing the antenna radiation pattern to its even and odd components for calculating $2\times $ 2-element subarray radiation pattern has fundamental limitations and none of four different $2\times $ 2-element and $4\times $ 4-element subarray configurations will entirely suppress the sidelobe issue of configured arrays. The accuracy of using embedded element pattern for calculating the radiation pattern of very large array antennas with identical subarrays is studied, and an accurate procedure for predicting array antenna radiation pattern is proposed. The appearance of undesired sidelobes has been examined, and optimal design for mitigating the sidelobe issue associated with the large array of identical subarrays with image configuration is presented.

Array Antenna Gain Enhancement With the Poynting Streamline Method

Streamlines of the Poynting vector field connect antenna figures of merit with the energy flow characteristics near a receiving antenna. Poynting streamlines properties and absorption aperture of antenna under different load conditions have been studied in this letter. Based on its Poynting streamline characteristics, the short-circuit dipole can be used as a parasitic element to direct the flow of energy, increase the absorption aperture, and enhance the gain of the array. Numerical examples show that this strategy can not only enhance the gain of dipole array, but also improve the gain of circularly polarized antenna array without deteriorating the axial ratio. Poynting streamline-based methods augment commonly used radiation-mode antenna analysis techniques by providing an intuitive and visual way to guide the design of antenna arrays.

Transmitter polarization optimization for space-time adaptive processing with diversely polarized antenna array

This paper considers the performance optimization of space-time adaptive processing (STAP) based on a diversely polarized antenna (DPA) array. A transmitter polarization design to enhance the detection performance is proposed. Accounting for the special structure of the polarization signal, we formulate the problem as a quasi-convex form based on the block majorization-minimization (MM) principle and solve it in an iterative framework. Compared with several existing methods, the proposed method has a quasi-convex form and can achieve better clutter suppression performance. We analyze the performance of conventional STAP and polarization-STAP (PSTAP), which indicates that the polarization diversity can help improve the performance of STAP for targets with low velocities, especially stationary ones. Simulations are conducted for validating the proposed methods and demonstrating their high performance.

Dual-Band Dual Circularly Polarized Antenna Array Using FSS-Integrated Polarization Rotation AMC Ground for Vehicle Satellite Communications

This paper presents a new dual-band dual circularly polarized (CP) high gain patch antenna array for vehicle satellite communications. The array consists of 16 linearly polarized dual-band elements backed with a new frequency-selective-surface (FSS)-integrated polarization rotation ground. The polarization rotation ground is located underneath the array, which not only acts as a reflector to increase the array boresight gain but also enables the array's dual CP radiation. The electromagnetic (EM) waves reflected by the ground retard either 90° or 270° with respect to the EM waves of the array directly radiated to the upper sphere at two frequency bands, leading to the dual-band dual CP radiation. This is totally different from many of the former counterparts which are based on either the perturbation on the stacked patch or external feeding network. Measured results show the −10-dB impedance bandwidth is from 7.8 to more than 8.5-GHz for X-band and from 14 to 15.3-GHz for Ku-band. The 3-dB axial ratio bandwidth is from 8.15 to 8.35-GHz for the lower band (right-hand CP) and from 14.2 to 14.8-GHz for the higher band (left-hand CP), respectively.

W-Band LTCC Circularly Polarized Antenna Array With Mixed U-Type Substrate Integrated Waveguide and Ridge Gap Waveguide Feeding Networks

In this letter, a low-temperature co-fired ceramic (LTCC) substrate integrated 8 × 8 circularly polarized (CP) antenna array is proposed for the wideband and high-gain W-band antenna-in-package application. By introducing the planar L-probe together with the original coupling probe, the E-fields in the substrate-integrated-waveguide (SIW) cavity are changed, and additional E-field components with a 90° phase difference are produced. Then, a CP antenna array is obtained. To reduce the losses in the feeding network, the gap waveguide technology is utilized with the SIW technology, as a mixed feeding network. To validate the proposed CP antenna array design, an 8 × 8 CP antenna array is fabricated by the LTCC technology and measured. Measured results show that the LTCC CP antenna array obtains a gain of 22.3 dBi, and its axial-ratio (AR) bandwidth is from 89 to 98.5 GHz for AR <; 3 dB. Besides, good agreements of the radiation patterns between the simulations and measurements are achieved within the operational frequency range.

Novel Low-RCS Circularly Polarized Antenna Arrays via Frequency-Selective Absorber

New electromagnetic (EM) structures are demonstrated to realize low-radar-cross section (RCS) antennas by making effective use of frequency-selective absorber (FSA). According to the well-known reciprocity principle, the twolayered FSA can be considered as an actual receiving antenna and then transformed to a circularly polarized (CP) antenna. At the radiation state, a truncated patch resonator on the bottom layer is fed by a coaxial probe so as to produce CP wave, and it further excites the slots on the upper layer, resulting in its radiation toward free space, and when the antenna at the stealth state, the detective incident wave can be effectively absorbed outside the radiation band, thus achieving RCS reduction. The design strategies are then explained and verified with the aid of the corresponding equivalent circuit models. Two examples of 2 × 2 and 4 × 4 antenna arrays were designed to validate the flexibilities of the proposed design method. Finally, the 4 × 4 antenna array was fabricated and measured, and reasonable agreement is achieved.

Shaped-Beam Circularly Polarized Antenna Array of Linear Elements for Satellite and SAR Applications

A circularly polarized planar antenna array consisting of linearly polarized elements is proposed for satellite and synthetic aperture radar applications. The individual linearly polarized elements are arranged in a linear or planar array form with the feed relations of the elements is adjusted to produce circularly polarized radiation. A subarray element of four λ/2 dipoles arranged in a planar cross form is proposed as a sub-element of the high gain arrays. Ten of these subarrays are arranged in a linear form to produce high gain circularly polarized radiation. The particle swarm optimization algorithm has been used in a new manner to reduce the computation time and producing reasonable results at the same time. This has been implemented by applying the PSO algorithm on two perpendicular linear arrays of point sources, without the need to apply the PSO to calculate the amplitudes and phases for the entire elements of the planar array. For 10 × 10 subarray elements arranged in a square planar form, an isoflux beam is generated in the range plane to realize 16° beamwidth radiation pattern with circular polarization. Also, another planar array of a cosecant squared beam is produced using the same array size in the range plane. The beam is flat-topped in the other perpendicular azimuth plane for both the isoflux and cosecant-squared shaped beams.

A Wideband Circularly Polarized Array Antenna With Compact and High-Efficiency Feeding Network

A wideband circularly polarized (CP) waveguide array antenna is proposed in this article. The proposed array antenna consists of four antipodally ridged elements and a compact feeding network with two orthogonal septa inserted to a stepped cavity. Both the components are wideband and they can work independently or together. The proposed topology gives a good solution to feed a $2 \times 2$ waveguide subarray which is the basis of large-scale arrays. It exhibits a larger working bandwidth than the array antennas fed by high-order mode cavities. A prototype is fabricated using 3-D printing and milling technologies. Measured results demonstrate a bandwidth of 40.3% from 9.9 to 14.9 GHz, in terms of the reflection coefficients less than −15 dB and the axial ratios smaller than 3 dB. An expanded $8 \times 8$ CP array antenna is explored based on the proposed $2 \times 2$ subarray to show the potentials of our design, and a total efficiency over 78% within a bandwidth of 38.7% is obtained by simulation.

Circularly Polarized Antenna Array With Low RCS Using Metasurface-Inspired Antenna Units

In this work, a circularly polarized (CP) antenna array with low radar cross section property based on CP metasurface-inspired antenna units is proposed. The polarization conversion metasurface is utilized as the radiator of the antenna. The in-band and out-of-band scattering of the antenna array under normal incidence is reduced by the chessboard configuration of the antenna units. Meanwhile, good radiation characteristics are realized by utilizing the sequentially rotated feeding network. The antenna prototype is fabricated and measured. The measured results show good agreement with simulated results.

Compact, High Directivity, Omnidirectional Circularly Polarized Antenna Array

A compact omnidirectional circularly polarized (OCP) antenna system is reported, which achieves high directivity and operates with the 2.4 GHz WLAN band. It is formed by cascading several stages of electric (metallic strips) and magnetic (loops) radiators into a highly compact array. Two OCP antenna array designs are developed to demonstrate the approach and their resulting high directivities. First, a four-stage OCP antenna array is presented. It consists of three electric radiators (E-radiators) and four magnetic radiators (M-radiators) arranged in collinear formation. A prototype was realized by mechanically fabricating the folded copper loops. Measurements confirm that this compact cost-effective design generates OCP fields that have a 5.1 dBic peak LHCP realized gain in its horizontal plane. The overlapped impedance and AR bandwidth cover 130 MHz from 2.34 to 2.47 GHz. Second, a six-stage OCP antenna array with helical loops is implemented to further increase the directivity. Its prototype was realized with all-metal 3-D printing technology. Six stages of bar and helical loop radiators form five E-radiators and six M-radiators. This highly compact OCP array achieves a measured maximum realized gain of 7.1 dBic with a 110 MHz operational bandwidth that covers 2.37-2.48 GHz.

Compact Self-Diplexing Dual-Band Dual-Sense Circularly Polarized Array Antenna With Closely Spaced Operating Frequencies

A novel self-diplexing aperture-shared dual-band dual-sense circularly polarized (CP) antenna array is proposed for transmitting/receiving (Tx/Rx) applications in X-band satellite communication systems. The antenna is capable of receiving the left-handed CP (LHCP) signals in the low band while transmitting the right-handed CP (RHCP) signals in the high band. First, a dual-port cavity-fed linearly polarized (LP) patch antenna with high isolation is developed as the element of the array. The element is composed of a slotted patch, a U-slot loaded substrate integrated cavity (SIC), and two groups of split-ring resonators (SRRs). The LHCP and RHCP operations are achieved by employing two sequentially rotated feeding networks which are isolated by a ground plane. To reduce the mutual coupling between the radiators, narrow slots are etched out in the center of the patches. Importantly, the sharing of patches at different bands (i.e., common aperture) enables a compact footprint to be achieved for the array, which is beneficial for suppressing undesirable grating lobes due to the reduced interelement spacing. The measured results of a fabricated prototype agree well with the simulations, showing an impedance bandwidth of 7.2–7.75 GHz (7.85–8.4 GHz), 3 dB axial ratio (AR) bandwidth of 7.4–7.7 GHz (7.95–8.32 GHz), and gain of 14 dBic (14.2 dBic) at the low band (high band). The channel isolation is over 27 dB and the sidelobe levels are below −15 dB in both bands. The demonstrated low-profile dual-band, dual-sense CP antenna array can be a good candidate for satellite communication.

Interference mitigation using a dual‐polarized antenna array in a real environment

This paper presents a new approach to interference mitigation. We propose to equip a Global Navigation Satellite System (GNSS) receiver with a diversely polarized antenna array in order to combine signal processing in the spatial and polarization domains in a novel way. The new algorithm is evaluated using measurement data, and results show significant improvement in receiver robustness against interferences when the dual-polarization approach is used. Two specific benefits come to light. First, the carrier-to-noise-density ratios of the line-of-sight components are improved since the receiver can make use of the power present on the left-hand circularly polarized (LHCP) channels because of non-ideal polarization purity of the antenna, resulting in better receiver computed position, velocity, and time (PVT) solutions. Second, interference mitigation becomes more effective because of the possibility of filtering in the polarization domain and the additional number of available degrees of freedom, increasing receiver robustness and enabling tracking and PVT in severe interference scenarios.

Through‐wall microwave imaging system using circularly polarised spiral antenna array

A new three-dimensional through-wall imaging (TWI) system is implemented for short range sensing. The system is equipped with a circularly polarised antenna array to improve image quality and reduce the wall artefacts. It consists of an array of 19 antennas positioned hexagonally. The array delivers half-space radiation with wideband performance, necessary for imaging applications. A differential tomographic imaging algorithm is developed to create through-wall images via both coherent and non-coherent processes. The imaging system has some advantages to traditional synthetic aperture radar approaches and other linear fixed aperture systems. It has a modular structure, uses both co-polarised and cross-polarised waves, capable of sensing conductive objects hidden behind dielectric layers (wall). The experimental results confirm that the new TWI system can create images of conductive objects hidden behind a dielectric wall clearly.

Millimeter-Wave Circularly Polarized Array Antenna Using Substrate-Integrated Gap Waveguide Sequentially Rotating Phase Feed

A substrate-integrated gap waveguide (SIGW) sequentially rotating phase (SRP)-fed 2 × 2 circularly polarized (CP) patch antenna array is presented for the wideband millimeter-wave application. The antenna element is composed of a truncated square patch, SIGW feedline with three layers of printed circuit board (PCB), and another layer of PCB with an air hole for supporting radiation patch. Each radiation patch is driven by an underneath coupling slot etched on SIGW. A wide axial-ratio (AR) bandwidth is achieved by deploying a 2 × 2 SIGW SRP feed network. Moreover, simple calculation expressions of the characteristic impedance and guide wavelength of SIGW are given for the design of SRP feed network. The fabricated prototype shows an impedance bandwidth of 25.6% covering 22.2–28.8 GHz, 3 dB AR bandwidth of 19% from 22.8 to 27.6 GHz, and peak gain of 11.53 dBic.

A Broadband Wide-Beam Circularly Polarized Antenna Array for Urban Macrocell Base Stations

An eight-element broadband wide-beam circularly polarized (CP) antenna array is developed for mobile wireless communications. The CP antenna element consists of two rectangular loops with gaps for circular polarization and parasitic elements for bandwidth enhancement. A wide beamwidth is achieved in the horizontal plane because the CP antenna elements have a narrow cross section in the plane. The CP antenna array also has higher isolation between antenna elements than a linear polarized (LP) array with the same element space, which is due to the polarization mismatch caused by the currents in the CP antenna elements. The eight-element CP antenna array achieves a bandwidth of 40% (1.7–2.55 GHz) for return loss >15 dB and a bandwidth of 47% (1.67–2.7 GHz) for axial ratio (AR) < 3 dB. The half-power beamwidth and the 3 dB AR beamwidth in the horizontal plane are ~65° ± 8° and approximately 100°, respectively. The antenna gain for the array is about 17 dBi. The CP antenna array is suitable for applications in urban macrocell base stations.

Printed RGW Circularly Polarized Differential Feeding Antenna Array for 5G Communications

In this paper, a differential feeding circularly polarized antenna array implemented with printed ridge gap waveguide technology for millimeter-wave applications is proposed. The differential feeding power divider is designed based on aperture coupling to achieve a stable 180° phase imbalance over 20% operating bandwidth at 30 GHz with sufficient matching level. This power divider is deployed to excite and test the proposed differential feeding antenna. The proposed antenna is formed by a rectangular aperture having a circular-shaped polarizer consisting of patch surrounded by an open-end ring, which is differentially fed. This polarizer is deployed to achieve a circular polarization radiation through a 10 % frequency bandwidth. A high-gain antenna array is implemented by extending the aperture size to have four radiating elements. The antenna array is fabricated, where the experimental results verify a −10 dB impedance bandwidth from 27.7 to 32.4 GHz (15.6%). Moreover, a 3 dB axial ratio bandwidth over 10 % is achieved, which is sufficient enough to cover the operating bandwidth of potential 5G applications at 30 GHz. The fabricated prototype achieves a 3 dB gain of 14 dB, with low cross polarization and a radiation efficiency higher than 84% over the whole operating frequency bandwidth.