A design of a series-fed antenna array without beam deterioration using miniaturized bandpass filters (BPFs) is proposed. The BPFs are connected behind branches of series feed network (SFN) to compensate the varied phase slope of paths, resulting in constant phase difference between elements across the bandwidth. Hence, the beam deterioration versus frequency is removed. The closed-form equations of the phase slopes for BPFs are deduced, and thus they can be designed quantitatively for phase slope balancing. The proposed SFN has advantages of compactness, simplicity, and low loss. For validation, an 8-element antenna array is designed and measured. The gain and sidelobe level are 12.2-12.39 dBi and 11.67-12.65 dB within the bandwidth of 5.2-5.8 GHz. As comparison, the gain and sidelobe level are 12.85-13.77 dBi and 7.18-12.75 dB using conventional feed network. Therefore, the designed antenna array has stable radiation pattern including beam direction, sidelobe level, and gain.
"Series-Fed Antenna Array Without Beam Deterioration Using Miniaturized Bandpass Filters for Phase-Slope Balancing," Progress In Electromagnetics Research M,
Vol. 121, 27-37, 2023. doi:10.2528/PIERM23021702
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