Smv. Iyer et al., OPTIMIZATION OF SUBSTRATE DIELECTRIC AND MODE OF MICROSTRIP RING ANTENNA FOR HIGH-EFFICIENCY AND DIRECTIVITY, Microwave and optical technology letters, 6(9), 1993, pp. 541-545
Theoretical formulation using the Green's function in conjunction with
the reflection coefficient matrix approach (instead of potentials) is
used for calculations of fields of microstrip ring antennas. Differen
t TM modes are studied using the magnetic cavity wall model for obtain
ing ring sheet currents. The results show that the ring antenna is sup
erior to disk and rectangular patch antennas and has optimized perform
ance for the TM12 mode, with a substrate dielectric constant of 6 with
high gain, broad lobe width and no side lobes. The better performance
at higher epsilon(r) may be of importance for array synthesis in MMIC
. The theoretical approach used is simpler for calculation and is easi
ly extendable to other situations and higher substrate thicknesses.