Frequency-Scanning Array Based on Dual-Band Filters With Wide Scanning Range and Flat Gain

A novel frequency-scanning antenna array using dual-band bandpass filters (BPFs) as phase-modulation components is proposed. First, the phase performances of BPFs with different orders are found to be proper to construct the feed network of frequency-scanning array with positive scanning angles. Second, the phase performance of the second passband is utilized and skillfully designed with 180° phase jump, targeting at the negative scanning angles. Third, the qualitative design of a set of dual-band BPFs which is exactly matched with required phase performance is put forward. Moreover, the dual-band antenna element with stable beamwidth and gain in two bands is designed. Consequently, a frequency-scanning array with wide scanning range and flat gain is obtained. For validation, a four-element frequency-scanning array is designed and measured with scanning range of ±60° and gain fluctuation of only 0.95 dB.