A high selectivity planar filtering quasi‐Yagi antenna

Abstract

A high selectivity planar filtering quasi-Yagi antenna employing the codesign of bandpass filter (BPF) and antenna is investigated in this article. A stubloaded resonator (SLR) and a half-wavelength resonator are utilized as the feeding network to excite the driven dipole of the quasi-Yagi antenna. The length of the driven dipole is about half-wavelength, which can be equivalent to the last stage resonator of BPF, achieving a good filtering gain response. To improve the frequency selectivity, an elaborate balun structure is utilized, and a transmission zero (TZ) on the lower side of the passband is acquired.Together with the TZ introduced by the SLR at the upper edge, the antenna can achieve a sharp band-skirt. An antenna prototype is fabricated and measured, showing a wide bandwidth up to 19.1% (from 3.1 to 3.76 GHz) with a flat gain response in band, an antenna peak gain of 4.85 dBi and a peak efficiency of À0.6 dB.

Designing a Compact Filtering Quasi-Yagi Antenna with Multiple Radiation Nulls Using Embedded Resistor-Loaded Arms

“…Some methods for designing a filtering quasi-Yagi antenna were reported. One method is cascading the filtering structure before the quasi-Yagi antenna, where the filtering structures, such as the bandpass filtering structure [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ], the bandstop filtering structure [ 12 ], and the filtering balun [ 13 , 14 , 15 , 16 , 17 ], determine the filtering response. Nevertheless, the filtering structures increase the whole size, especially in the endfire direction, and additional loss is inevitable.…”