基于小间距低耦合阵元的微带天线阵设计

Design of Microstrip Antenna Array Based on Mutual Coupling Reduction between Very Closely Spaced Patch Antennas

设计微带天线阵时,减小阵元间距会导致阵元间耦合增加,从而导致增益下降(在考虑口径增益减小的基础上进一步下降)。针对该问题,提出一种减弱小间距阵元间耦合的新方法,即通过在地板上蚀刻两条共面波导,引入新的幅度可调的耦合去抵消原有耦合,从而实现减小阵元间耦合的目的。该方法将邻边间距为0.024λ_0(λ_0是自由波长,中心间距约0.38λ_0)的阵元之间的隔离度(|S_(21)|)从6.1dB提高到21dB以上,改善了阵元的辐射特性,使每个阵元的辐射方向图接近单个贴片的辐射方向图。为验证有效性,本文基于该方法设计了一副二元微带天线阵,并对其进行测试,与等口径面的二元阵比较,增益提高了约1.2dBi,与等增益的二元阵比较,面积减少了约10.2%,且副瓣电平有较大改善。

When designing microstrip antenna array, reducing the space between array elements can lead to mutual coupling increasing, which decreases the gain of antenna. In this letter, an efficient mutual coupling reduction method is in- troduced for very closely spaced microstrip antennas. Through two simple coplanar waveguide （CPW） neutralization lines on the ground plane, the field inside the first element is guided to second element creating another path for mutual coupling, the phase and amplitude of which may be varied to neutralize the original existing mutual coupling between the elements. More than 21dB isolation （ [$21 I ） is achieved with a very close distance of about 0. 024λ0（ edge-to-edge distanceλ0, is free space wavelength） and 0.38 （center-to-center distance）. Radiation characteristic of array element is improved, the radiation pat- tern of which is close to radiation pattern of a single patch. In order to validate the propose method, a two-element array based on it is designed and measured. Compared to a two-element array with the same size, the gain of the proposed array is improved by 1.2dBi and compared to a two-element array with the same gain, the size is decreased by 10.2% as well as a obvious improvement of side lobe.