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

In this paper, a compact quasi-Yagi antenna with embedded resistor-loaded arms is proposed to obtain filtering response four radiation nulls. The achieve two additional nulls caused by reverse currents and absorb the unwanted out-of-band resonant points brought themselves. director close driver provides point null opposite between director. Compared other antennas, one can size along endfire direction. For demonstration, balun-integrated prototype covering 5G band N78 (3.3–3.8 GHz) designed direction (without ground) of 0.13 λ0 (λ0 wavelength in free space at center frequency), measured results show 10 dB impedance-matching bandwidth 22.9% (3.21–4.04 GHz), nulls, peak gain 4.73 dBi.