Dual-polarized Array Research Articles

Research on dual-polarized circular waveguide antenna fed by L-shaped probes

This paper researched a kind of dual-polarized and cylindrical waveguide antenna fed by two L-shaped probes at the antenna bottom. The designed antenna was composed of two orthogonal L-shaped coaxial probes and a cylindrical waveguide cavity. The two orthogonal field structures were excited and the dual-polarized radiation mode was formed. The feeding cables of two polarization ports went through the bottom of the cylindrical cavity and were connected with the microwave adaptors. The bottom feeding structure was suitable to constitute a planar antenna array. The electromagnetic simulation and optimization design of the proposed antenna were carried out by using the full wave electromagnetic simulation technique, and the simulation results showed that the isolation between two polarization ports were more than 20dB within the frequency range of 4.8–5.4GHz. At the center frequency, the cross-polarization levels of radiation pattern were lower than −21dB at the boresights and the beam width of radiation patterns at E-plane and H-plane were more than 70° for two polarization ports. The designed antenna in this paper was fabricated and measured. The measurement results indicated that the designed antenna achieved anticipated radiation performances and design effectiveness of the dual-polarized antenna in this paper was proved. The dual-polarized and cylindrical waveguide antenna is suitable for some application fields such as dual-polarized array radar. The research results in this paper can provide a technical basis for the practical engineering application.

Mutual Coupling Reduction Using Meta-Structures for Wideband, Dual-Polarized, and High-Density Patch Arrays

A mutual coupling reduction strategy that employs meta-structures is introduced for wideband, dual-polarized, high-density, planar, and patch antenna arrays. The meta-structures consist of two types of resonators: grounded capacitively loaded loops (GCLLs) and $\pi$ -shaped elements. By incorporating the meta-structures into the array configuration, the isolation levels between adjacent radiating elements in both the E- and H-planes orientations are improved by as much as 7.15 dB. The surface current distribution behaviors of the array with only the GCLLs and with only the $\pi$ -shaped elements are investigated thoroughly to explain the mutual coupling reduction mechanisms. A proof-of-concept array was constructed and tests were performed that validate the reported design principles and simulation results.

Harmonic suppression of a dual-polarized microstrip array by using microstrip stubs

A compact dual-polarized two-element microstrip antenna array has been designed at 3.5 GHz frequency band and the higher order modes up to second harmonics have been successfully suppressed for two orthogonal modes. Two pairs of microstrip stubs of electrical lengths λg1/4 (λg1 = wavelength of 1st harmonic signal) and λg2/8 (λg2 = wavelength of 2nd harmonic signal) respectively have been integrated with the microstrip feed line and two harmonics and a sub-harmonic of the fundamental mode have been reduced. The design offers a port isolation of more than 23 dB over the operating band and the measured bandwidths of the two polarizations of 250 and 275 MHz, respectively, are reported. Simulated and measured results show that the harmonic components exist at 7.05 GHz (1st harmonic, TM20), 10.45 GHz (2nd harmonic, TM30) and also a sub-harmonics at 5.5 GHz (TM12 of the fundamental frequency have been successfully suppressed. The harmonic properties of microstrip antenna with and without stubs have been studied and the result indicates that the harmonic components of the array for two orthogonal polarizations have been well eliminated because of the effect of the tuning stubs. To validate the concept the prototypes were fabricated, tested and compared with the simulated results.

Low-Cost X/Ku/Ka-Band Dual-Polarized Array With Shared Aperture

This paper presents a novel tri-band (X/Ku/Ka-band) planar antenna array with dual polarizations and shared aperture. Compared with traditional dual-polarized arrays, the proposed array has advantages of low cost, low profile, and high integration. Three types of antennas resonating at different frequencies, including the perforated patch, stacked patch, and slim crosspatch, are innovatively interleaved in the same aperture. The crosspatch fed by proximity coupling is presented as Ku-band element for its advantages of compact size, high isolation, and pure polarization. The techniques such as series feed and reverse feed are utilized to implement the six feed networks in a compact size with reduced cross polarizations. Measured results agree well with the simulations, showing three operation bands at X-, Ku-, and Ka-bands with the bandwidths of 3.6%, 6.7%, and 5.3%, respectively. The antenna also exhibits excellent radiation performance with the cross-polarization discrimination over 25 dB at the three bands. To the best of the author’s knowledge, this is the first shared-aperture X/Ku/Ka-band dual-polarized antenna array reported, which is useful for potential synthetic aperture radar applications.

A Miniaturized Linear Wideband Phased Array with Dual-Polarization

ABSTRACTIn this article, a novel miniaturized dual-polarized linear wideband phased array (1 × 16) that operated from 0.45 to 2.5 GHz (5.5:1) is introduced. Although the design of the proposed array is based on the tightly coupled dipoles arrays (TCDA) concept, the proposed array is more difficult to design than the traditional TCDA. Conventionally, the dual-polarized TCDA is usually shown as a square or rectangle planar array for pursuing good performance by using the couplings between the elements. However, to a linear dual-polarized TCDA, only one element is set in the direction of the vertical polarization (V-polarization) or horizontal polarization (H-polarization). No periodicity and no couplings between the elements can be utilized to keep the performance of wide bandwidth. In order to solve this problem and keep the performance in this polarization, the shapes of the element and the ground are designed carefully. The proposed array is designed as a linear array, in which there are 16 unit cells and each unit cell consists of only one horizontal polarized (H-polarized) element and one V-polarized element (1 × 1). The array achieves a low total profile (0.13λlow). The array exhibits a measured active VSWR < 3.0 at broadside and VSWR < 3.3 at = 45° in the azimuth plane. Agreement with simulations presented in this article reveals the feasibility of the design.

A Shared-Aperture Dual-Band Dual-Polarized Filtering-Antenna-Array With Improved Frequency Response

In this paper, a novel dual-band dual-polarized array antenna with low frequency ratio and integrated filtering characteristics is proposed. By employing a dual-mode stub-loaded resonator (SLR) to feed and tune with two patches, the two feed networks for each polarization can be combined, resulting in the reduction of the feed networks and the input ports. In addition, owing to the native dual resonant features of the SLR, the proposed antenna exhibits second-order filtering characteristics with improved bandwidth and out-of-band rejections. The antenna is synthesized and the design methodology is explained. The coupling coefficients between the SLR and the patches are investigated. To verify the design concept, a C-/X-band element and a $2 \times 2$ array are optimized and prototyped. Measured results agree well with the simulations, showing good performance in terms of bandwidth, filtering, harmonic suppression, and radiation at both bands. Such an integrated array design can be used to simplify the feed of a reflector antenna. To prove the concept, a paraboloid reflector fed by the proposed array is conceived and measured directivities of 24.6 dBi (24.7 dBi) and 28.6 dBi (29.2 dBi) for the X-polarization (Y-polarization) are obtained for the low- and high-band operations, respectively.

Electromagnetic Simulation and Alignment of Dual-Polarized Array Antennas in Multi-Mission Phased Array Radars

Electromagnetic (EM) simulation of dual-polarized antennas is necessary for precise initial alignments, calibration and performance predictions of multi-function phased array radar systems. To achieve the required flexibility and scalability, a novel Finite-Difference Time-Domain (FDTD) solution is developed for rectangular, cylindrical and non-orthogonal coordinate systems to simulate various types of array antenna manifolds. Scalable array pattern predictions and beam generations are obtained by combining the FDTD simulation solutions with the Near-Field (NF) chamber measurements. The effectiveness and accuracy of this approach are validated by comparing different simulations and comparing simulations with measurements.

Design of a printed non‐planar dual‐polarised log‐periodic dipole array

An efficient and low cost approach to realise a non-planar dual-polarised log-periodic dipole array antenna (LPDA) using printed circuit board technology is proposed which achieves a high bandwidth and operational frequency. The proposed antenna utilises a very short transition from a coaxial cable to a balanced four-conductor transmission line to realise an ultra-wide bandwidth balun and input impedance matching. An analysis of the utilised four-conductor transmission line alongside its comparison to two-conductor transmission line of a planar LPDA is also presented. Two prototypes of the antenna operating over the frequency ranges of 1–13 GHz and 1–18 GHz were designed, fabricated, and tested. An average gain of 6.7 dBi is obtained. Measured voltage standing wave ratio, cross-polarisation and front-to-back ratio of both prototypes are better than 2.6, −14, and 22 dB respectively.

Statistical Method With Dual-Polarized MIMO Array for Target Discrimination

Controlling the polarization information in transmit waveforms based on the property of the target scattering matrix provides better performance than transmitting waveforms with fixed polarizations. In this letter, we propose a radar scheme called dual-polarized MIMO array, and study the target discrimination method under the active-decoys scenario with the proposed radar system. The polarization diversity is employed in transmit antennas and receive antennas. We transform the target discrimination problem into a binary hypothesis problem and design the Neyman-Pearson discriminator by statistical analysis. Otherwise, the discrimination performances for the true target and the false target are analyzed. Using numerical simulations, we demonstrate that optimal design of the transmitter and receiver polarizations provides improved discrimination performance over the radar with only horizontally and vertically polarized transmit antennas.

A Broadband Dual-Polarized Dual-OAM-Mode Antenna Array for OAM Communication

The generation of multimode orbital angular momentum (OAM) carrying beams has attracted more and more attention. A broadband dual-polarized dual-OAM-mode uniform circular array is proposed in this letter. The proposed antenna array, which consists of a broadband dual-polarized bow-tie dipole array and a broadband phase-shifting feeding network, can be used to generate OAM mode −1 and OAM mode 1 beams from 2.1 to 2.7 GHz (a bandwidth of 25%) for each of two polarizations. Four orthogonal channels can be provided by the proposed antenna array. A 2.5-m broadband OAM link is built. The measured crosstalk between the mode matched channels and the mode mismatched channels is less than −12 dB at 2.1, 2.4, and 2.7 GHz. Four different data streams are transmitted simultaneously by the proposed array with a bit error rate less than 4.2×10-3 at 2.1, 2.4, and 2.7 GHz.

Low Cross-Polarization Vivaldi Arrays

This paper introduces a Vivaldi-type ultra-wideband antenna array with low cross-polarization, termed the Sliced Notch Antenna (SNA) array. High cross-polarization when scanning in the non-principal planes has long been a problem in Vivaldi arrays without a universal solution. In this paper, we shed light on the root cause of this long-standing issue, clarifying that a high ratio of vertical-to-horizontal current potentials along the upper radiator fin is primarily responsible for elevated cross-polarization (and not strictly the element profile). This finding therein motivates the main technical innovation in the present work—a simple reconfiguration of the upper Vivaldi fin into a series of coupled conductor segments to effectively control the aforementioned current ratio for significant reductions in cross-polarization, without reducing element profile or considerably hindering the excellent match and radiation efficiency of the original Vivaldi. Theory and design methodology for the SNA array are formulated, and followed by a concise set of design guidelines that are applied to reconfigure a representative 10:1 Vivaldi element into an SNA for practical reference, exhibiting a 20 dB reduction in peak cross-polarization ratio. This paper considers the case of single-polarized arrays as a first introduction to the SNA, though the method has been verified to work equally well (if not better) in dual-polarized arrays.

Design of Wideband and Dual Polarized Cavity Antenna Planar Array

A $6 \times 6$ wideband antenna array with ±45° dual polarizations is proposed. To achieve good radiation efficiency, cavity antenna is used in this work as the basic element. Feeding probes and strip line feeding networks are printed on general PCB substrate. The feeding circuits for exciting different polarizations are stacked and multilayer substrate step structure is used. Here, strip line to downward SMA connector transitions is also designed, which aids in integrating the proposed array with T/R modules located below and extending it to larger phased array. The antenna array is fabricated and measured. Simulated and measured impedance and radiation performances are also given and compared. The proposed antenna arrays show wide bandwidth of 30% from 10.9 to 14.8 GHz, and isolation of higher than 33 dB is also exhibited across the bandwidth. Furthermore, symmetrical patterns and cross-polarizations of below −25 dB are also demonstrated.

Eight-Port Orthogonally Dual-Polarized Antenna Array for 5G Smartphone Applications

A dual-polarized hybrid eight-antenna array operating in the 2.6-GHz band (2550–2650 MHz) for 5G communication multi-input multi-output (MIMO) operation in the smartphone is presented. The proposed hybrid antenna array elements are symmetrically placed along the long edges of the smartphone, and they are composed of two different four-antenna array types (C-shaped coupled-fed and L-shaped monopole slot) that exhibit orthogonal polarization. Therefore, coupling between the two antenna array types can be reduced, and the MIMO system performances are enhanced. A prototype of the proposed eight-antenna array is manufactured and measured. A good impedance matching (10 dB return loss or better), desirable cross-polarization discrimination (better than 15 dB), and an acceptable isolation (better than 12.5 dB) are obtained. Envelope correlation coefficient and channel capacity are also calculated to evaluate the MIMO performances of the proposed antenna array.

Wideband Dual-Polarized and Dual-Monopulse Compact Array for SAR System Integration Applications

A wideband dual-polarized and dual-monopulse array with highly self-compact configuration is proposed for synthetic aperture radar (SAR) applications. To investigate the monopulse performances, a monopulse comparator network integrated with a 16 $\times$ 32 antenna array is designed to form a complete monopulse array. In order to realize the complicated monopulse array and avoid the disadvantages from conventional machining methods in manufacturing waveguide structures, a 3-D metal-direct-printing technique is adopted in this work to obtain better mechanical and electrical performances. Experimental results show that the monopulse array can operate in a wide bandwidth of 12.5% in the Ku-band. Port isolation and polarization isolation better than 30 and 45 dB are achieved, respectively. Furthermore, satisfactory monopulse performances in sum- and difference-patterns are also obtained in the wideband. In particular, a high efficiency of 95% is achieved at the center frequency of the sum-patterns, validating the design feasibility and merit of the 3-D printing technique in SAR applications.

A 6:1 Bandwidth, Low-Profile, Dual-Polarized Ring Array of Spiral Antennas With Connecting Arms

In an earlier work, the design of a 2:1 bandwidth dual-polarized phased array of Archimedean spiral antennas with cavity was presented. The reflection coefficient, circular polarization, and grating lobes goals were obtained independently in the design process. The low end of the final bandwidth was constrained to the frequency cutoff of the spiral antenna, at the low end of its bandwidth. In this communication, an extension of the bandwidth of the array is achieved by connecting the spiral antennas of the array. Hence, with the same size, the bandwidth is enlarged almost three times (a total of 6:1). The measurements confirm the simulations. The array can scan up to $\theta=30^\circ$ keeping a low reflection coefficient, good right- and left-hand circular polarization, low-sidelobe levels, and using a low-profile cavity.

Characterization of a Dual-Polarized Connected-Dipole Array for Ku-Band Mobile Terminals

In this paper, we present the characterization of a Ku-band connected-dipole array for mobile Satcom application. The prototype array consists of $2 \times 256$ dipole radiators arranged in a square grid, to form $16 \times 16$ dual-polarized cells. It has been designed to operate over a wideband ranging from 10.7 to 14.5 GHz (30%), accommodating in a single antenna both the transmit (14.0 to 14.5 GHz) and the receive (10.70 to 12.75 GHz) bands for the application. The array has been characterized in terms of active reflection (AR) and radiation patterns. Dedicated test support equipment (TSE) has been developed and used to test the array radiation characteristics. Over the frequency range of operation, the array maintains good matching (ensuring system gain to noise temperature better than 8 dB/K) and good radiation performance while scanning as far as 60° in all the azimuth planes. The cross-polarization suppression is better than 15 dB within most of the scan range and reaches 10 dB for the extreme scan angles in the diagonal plane.

A 94-GHz Dual-Polarized Microstrip Mesh Array Antenna in LTCC Technology

This letter reports a microstrip mesh array antenna in a low temperature co-fired ceramic (LTCC) technology for 94-GHz applications. The microstrip mesh array antenna enlarges the system polarization diversity with the capability of being utilized to support the simultaneous reception in two orthogonal polarizations, as well as transmission in either polarization. The proposed design is composed of two grid arrays in two orthogonal directions, where matching stubs are specially designed to compensate the alteration of input impedance due to the direct coupling of the complementary array of another polarization. The dual linearly polarized microstrip mesh array antenna achieved a measured maximum realized gain of 13.3 dBi at 93.6 GHz, a 10-dB impedance bandwidth of 6.91%, and 3-dB gain bandwidth of 1.70% at 94 GHz as a one-port antenna.

Multimode Resonator-Fed Dual-Polarized Antenna Array With Enhanced Bandwidth and Selectivity

A novel design concept of multimode filtering antenna, which is realized by integrating a multimode resonator and an antenna, has been applied to the design of dual-polarized antenna arrays for achieving a compact size and high performance in terms of broad bandwidth, high-frequency selectivity and out-of-band rejection. To verify the concept, a $2 \times 2$ array at C-band is designed and fabricated. The stub-loaded resonator (SLR) is employed as the feed of the antenna. The resonant characteristics of SLR and patch as well as the coupling between them are presented. The method of designing the integrated resonator-patch module is explained. This integrated design not only removes the need for separated filters and traditional ${50}{\text - }{\Omega }$ interfaces but also improves the frequency response of the module. A comparison with the traditional patch array has been made, showing that the proposed design has a more compact size, wider bandwidth, better frequency selectivity, and out-of-band rejection. Such low-profile light weight broadband dual-polarized arrays are useful for space-borne synthetic aperture radar (SAR) and wireless communication applications. The simulated and measured results agree well, demonstrating a good performance in terms of impedance bandwidth, frequency selectivity, isolation, radiation pattern, and antenna gain.

Design and realization of a novel nonplanar dual-polarized log-periodic dipole array for 1-13 GHz

A feasible and low cost approach to implement a nonplanar dual-polarized log-periodic dipole array antenna using printed circuit board (PCB) technology is proposed. The proposed antenna utilizes a very short transition from a coaxial cable to a balanced twin-lead transmission line to realize an ultrawide bandwidth balun, and has two distinct scaling factor values for high and low frequency elements. A prototype of the antenna operating over the frequency range of 1–13 GHz was designed, fabricated, and tested. An average gain of 7 dBi is obtained. Measured VSWR, cross-polarization and front-to-back ratio are better than 2.6, −16 dB, and 22 dB, respectively.

Support vector machine classification of woody patches in New Zealand from synthetic aperture radar and optical data, with LiDAR training

A light detection and ranging canopy height model (CHM) was used as training data for a segment-based classification of woody patches. The classifier is accurate (∼92%) and suitable for use at the national scale. Height thresholds and percentage cover of vegetation from the CHM were used to produce larger quantities of reliable training data compared to other, mostly point or plot-based, ground-truthing approaches. It was found that the regional-scale differentiation between woody and nonwoody vegetation might be achieved by a combination of L-band dual-polarized Phased Array type L-band synthetic aperture radar data (HV) with multispectral optical data that include a short-wave infrared band. The application of a support vector machine algorithm to these data proved successful. The versatility of these algorithms regarding the discrimination function and their ability to solve classification problems with multiple output classes were critical factors for success. The identified and classified woody patches constitute a valuable addition and enhancement of the national land cover database.