Accession Number : ADP004616

Title :   Circularly Polarized Microstrip Antennas,

Corporate Author : ILLINOIS UNIV AT URBANA ELECTROMAGNETICS LAB

Personal Author(s) : Lo,Y. T. ; Engst,B. ; Lee,R. Q. H.

Report Date : JAN 1985

Pagination or Media Count : 22

Abstract : It is well known that a simple microstrip antenna can be made to radiate EM waves of any polarization, in particular, the circular polarization (CP) without any phasing network and power divider. A simple but surprisingly accurate theory for this family of antennas has been developed and reported in the 1979 Antenna Applications Symposium. However, the CP bandwidth, (CPBW) namely the bandwidth in which the axial ratio (AR) is less than a certain specified value, say 3 dB, is very small. For example, for a nearly square patch made of 1/16 in. thick Rexolite 2200 and designed to operate at 800 MHz, the CP bandwidth is only about 0.3%. Most of those experimental designs were made for a feed placed along the diagonal of the patch. But the theory shows that there are practically infinitely many possible designs with different feed locations. The purpose of this paper are: first to clear up the speculation that other designs might give a wider bandwidth, and second to show an effective method for broadening the bandwidth. (Author)

Descriptors :   *ANTENNA ARRAYS, *STRIP TRANSMISSION LINES, POLARIZATION, PHASED ARRAYS, POWER DIVIDERS, ELECTROMAGNETIC RADIATION, BANDWIDTH

Distribution Statement : APPROVED FOR PUBLIC RELEASE