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(degrees) 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(degrees) and gain fluctuation of only 0.95 dB.