A Novel Wideband Reflectionless Filtering Patch Antenna
Shuai Gao,
Zhongbao Wang,
Hongmei Liu and
Shao-Jun Fang
In this paper, a novel wideband reflectionless filtering patch antenna is proposed. The antenna consists of a filtering patch and an absorption network. The filtering patch includes an E-shaped radiator and two T-shaped radiators. The E-shaped radiator introduces a radiation null, which greatly improves lower-band edge selectivity. The T-shaped radiators introduce an additional radiation null, effectively increasing the filtering performance in the upper stopband. For the absorption network, a quarter-wavelength coupled-line section with two 200-ohm resistors and four short-circuited three-quarter-wavelength transmission lines are used to achieve reflectionless characteristics. To demonstrate the design, an antenna prototype with a center frequency of 3.5 GHz is fabricated and measured. Measurement results manifest that the input reflectionless bandwidth is 63.5% from 2.56 to 4.94 GHz with an antenna gain of 5.8 dBi. At 3.02 and 3.91 GHz, two radiation nulls are also obtained. The lower and upper stopband suppression levels are 18.1 and 14.5 dB, respectively.