A broadband filtering quasi‐YAGI antenna with wide stopband

Abstract

This article presents a novel filtering quasi‐Yagi antenna with ultra‐wide passband and ultra‐wide stopband. By employing an antipodal connection between the dipole arms and the feedline, the profitable modes of the dipole can be excited and controlled to produce a wide operating band. Without increasing the antenna size, the elaborately arranged parasitic elements and the band‐stop element can realize the filter‐like response with sharp roll‐off rates and high out‐of‐band suppression levels. Measured results show that passband and stopband can be improved to 2.65–6.05 GHz (78.2%) and 6.3–13.3 GHz (up to 3.1 f0, f0 is the center frequency of the antenna), respectively. Radiations keep stable across the passband. The measured in‐band average gain is ∼ 4.4 dBi, whereas the out‐of‐band radiation suppression is more than 20.2 dB.

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

“…Nevertheless, the filtering structures increase the whole size, especially in the endfire direction, and additional loss is inevitable. Adding the parasitic structure into the quasi-Yagi antenna is another method for creating a filtering quasi-Yagi antenna, for example, inserting a double-sided parallel-strip line (DSPSL) filter between the driver and the reflector to enhance the frequency selectivity [ 18 ], which adds a parasitic structure between the driver and director to produce two radiation nulls [ 19 , 20 ]. Although the size of the antenna is not increased when introducing the filtering response, the size along the endfire direction is still large to maintain the performance.…”