A modified equilateral-triangular-ring microstrip antenna for circular polarization

This paper presents a new design of a probe-fed circularly polarized equilateral-triangular-ring (ETR) microstrip antenna. In this design, the ETR patch is modified to have a truncated tip and a Y-shaped conducting strip of equal arm lengths centered in the pitch center and connected to the three tips of the patch. With the proper size of the truncated tip, the splitting of the fundamental resonant mode of the modified ETR microstrip antenna into two near-degenerate orthogonal modes for circular polarization (CP) radiation can be achieved by using a single probe feed located in the Y-shaped conducting strip. In addition to the good CP radiation obtained, the proposed modified ETR microstrip antenna can perform CP radiation with a reduced antenna size as compared to a regular circularly polarized equilateral-triangular microstrip antenna at a fixed operating frequency. (C) 1999 John Wiley & Sons, Inc.