OPTIMIZATION OF SUBSTRATE DIELECTRIC AND MODE OF MICROSTRIP RING ANTENNA FOR HIGH-EFFICIENCY AND DIRECTIVITY

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.