Studies of CPW-fed equilateral triangular-ring slot antennas and triangular-ring slot coupled patch antennas

Designs of coplanar waveguide (CPW)-fed equilateral triangular-ring slot antennas with tuning-stub and triangular-ring slot coupled patch antennas are proposed and experimentally investigated. The impedance matching of the resonant frequency can be obtained only by adjusting the tuning-stub length for the proposed triangular-ring slot antenna with tuning-stub. For the design of ring-slot coupled patch antenna, slightly changing the patch size causes the tunable frequency-ratio f/sub 2//f/sub 1/ between the first two operating frequencies to fall in the range of about 1.1-1.42. Details of the proposed designs are investigated by experimental as well as theoretical studies.

I. Introduction

Ring SLOT antennas have been analyzed and designed for wireless communication systems. It is found that the perimeter of the slot ring is equivalent to about one and a half guided wavelengths of the first operating frequency of the conventional coplanar waveguide (CPW)-fed ring slot antennas [1], and about one guided wavelength for microstrip feedline at proper tuning-stub length [2]. In addition, the length of a conventional dipole slot antenna is about a half guided wavelength with a capacitive type feed, and about one guided wavelength for inductive type feed. In this study, a tuning-stub will be introduced to a conventional CPW-fed triangular-ring slot antenna for lowering the first operating frequency. The proposed and conventional slot-ring antennas are constructed by adding the same slot at two ends of the modified dipole slot antenna with capacitive and inductive type feed, respectively. Thus, it is expected that the resonant frequency of the proposed slot-ring antenna is lower than that of the conventional slot-ring antenna. A conventional CPW-fed triangular-ring slot antenna will be fabricated for comparison.