A Microstrip Magnetic Dipole Yagi–Uda Antenna Employing Vertical I-Shaped Resonators as Parasitic Elements

摘要

A low-profile planar Yagi-Uda antenna with exact endfire radiation and vertical polarization is presented in this paper. The concept is the combination of an aperture element and a novel vertical I-shaped resonator (VISR). The aperture acts as the driven antenna, which can be equivalent of a virtual magnetic dipole. The VISR array constructed with VISR unit cell is employed as a director or a reflector element depending on the resonant frequency of the unit cell, which consists of two identical rectangular metal conductors printed on both sides of a substrate and their electrical connection using via holes. Two prototype antennas are then designed, fabricated, and measured to test the validity of the operating principle. Antenna I with one director and one reflector achieves an endfire realized gain of 9.9-10.3 dBi and a front-to-back ratio (FBR) of more than 17.4 dB across 6.36-6.70 GHz. With four directors and one reflector, an endfire realized gain of 12.9-13.6 dBi and an FBR of more than 17.9 dB are accomplished by antenna II across 6.38-6.71 GHz. Moreover, a sensitivity analysis is implemented for the proposed antennas. Simulated results show that the standard PCB process is a reliable method for antenna fabrication.