Showing papers by "Guifu Zhang published in 2020"

A Crossed Dipole Phased Array Antenna Architecture With Enhanced Polarization and Isolation Characteristics

Abstract: A dual-polarized planar phased array antenna with enhanced polarization and isolation characteristics for multifunction applications is presented. A bent crossed dipole is selected as the element of the array antenna. The bend angle is optimized to widen the E-plane active element pattern of the dipole resulting in a pair of matched co-polar patterns. Contrary to common patch array antennas, this design does not require a continuous grounded substrate. This diminishes the surface wave propagation along the ground plane. Efficient techniques, applied to the element design, isolate the two polarizations from each other. Higher than 40 dB port isolation is achieved within the entire frequency range of 2.7–3.0 GHz in principal plane scanning. In order to preserve the symmetry of the array antenna, a mirrored arrangement in both orthogonal directions is applied to the array configuration. This enhances the co- to cross-polarization levels to better than 45 dB in scanning up to ±45° in the principal planes. The proposed phased array antenna with enhanced polarization purity can potentially improve polarimetric performance.

Dual-Polarized Perpendicularly Fed Balanced Feed Antenna With High Polarization Purity

Abstract: The design and analysis of a high-performance dual-polarized perpendicularly fed microstrip patch antenna are presented. The planar balanced feeding technique has been evolved to a highly isolated nonplanar method for exciting a dual-polarized microstrip patch antenna. Reducing the number of parallel dielectric and ground plane layers improves the isolation between polarization and increases the antenna scan capability. The simulation and measurement results of the proposed antenna are presented. The proposed antenna possesses high-performance electromagnetic characteristics. Input isolation of better than 52 dB between orthogonal polarizations in the entire frequency band of 2.7–2.9 GHz and cross-polarization level of better than $-$ 32 dB have been achieved in the measured results.

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

Abstract: 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.