A New Method for Linear Antenna Array Design
Yang WANG1, Jinming DONG2,
1 RF Lab (Hong Kong) Limited, Room 414, 4/F., International Plaza, 20 Sheung Yuet Road, Kowloon Bay, Kowloon, Hong Kong,China
2 Electronic Engineering Department, Beihang University, 37 Xueyuan Road, Beijing 100083, China
Email: yang_t_wang@hotmail.com.
The inherent relation between the linear antenna array and the finite impulse response filter of digital signal processing is revealed and the least square linear-phase finite impulse response filter design method is introduced for the linear antenna array to obtain a similar main lobe width of uniform linear antenna array but much lower sidelobe level.
Introduction: The linear antenna array (LAA) is a widely used for airborne target detection. The main efforts are focusing on reducing its sidelobe level while trying to keep the main lobe being narrow. In addition, the phase control concept was introduced to allow the LAA scanning, and the uniform linear antenna array (ULAA) is always the research platform [1]. From the LAA phase point of view, the ULAA is just the finite impulse response (FIR) filter of digital signal processing (DSP) [2] with the rectangle window function (RWF). Beside RWF, there are many high-performance ones available for LAA design. However, the availability of low sidelobe level is at the price of the wider main lobe for the window functions based LLA. A more effective FIR filter design method called least-square linear-phase design can be employed for the LLA design to balance the tradeoff between the low sidelobe level and narrow main lobe.
The relation between LLA and FIR Filer: The LAA can be shown as Fig.1. The distance d between the adjacent elements is \(\lambda/2\), where λ is the wavelength; and the incident angle is\(\theta\). So, the phase difference between the adjacent elements is kdcos\(\theta\), where k is 2\(\pi\)/\(\lambda\).