Radiation characteristics of microstrip fed Yagis placed on a rectangular dielectric plate of finite dimensions.

摘要

Printed Yagi or microstrip-fed Yagi Uda antennas placed on dielectric plates of finite dimensions are a natural evolution of wire Yagis. Due to recent developments in the area of wireless communication systems these antennas can be useful as they are compatible with microstrip circuitry used in microwave devices. The basic antenna concept involves printed dipole antenna element fed by a microstrip line to a balun transition. This antenna system is actually a two-element Yagi with a ground plane acting as a reflecting element and the dipole being the feeding element. The concept can be extended to lengthened or thickened dielectric plates with or without the inclusion of the parasitics. Such antennas enjoy good impedance bandwidth and low levels of cross polarization.; Directors prevent the higher order mode(s) from radiating thus narrowing the beam and increasing the directivity. Similar results can be achieved with longer plates although they are not able to prevent the higher order mode(s) from radiating as well as the parasitics do; patterns do however enjoy lower sidelobes. (Abstract shortened by UMI.)