Design concepts for broadband antenna arrays with constant half-power beamwidth

This paper reports on the design of broadband antenna arrays with constant half-power beamwidth (HPBW). The proposed concept is based on non-uniformly spaced and non-uniformly-fed radiating elements using frequency-selective feeding networks. As opposed to conventional feeding schemes, it facilitates the realization of constant HPBW within two octaves of bandwidth. For proof-of-concept demonstration purposes, the radiation characteristics of a five-element array are studied for frequencies between 1–4 GHz. The proposed frequency-selective feeding scheme allows for HPBW of 45°±2° and HPBW variation of 9.3 % to be obtained within the entire 1–4 GHz range.