FULL-WAVE ANALYSIS OF A DISK-LOADED SPHERICAL ANNULAR-RING MICROSTRIPANTENNA

In this article we analyze the effect of the disk loading on the chara cteristics of a spherical annular-ring microstrip antenna. The antenna is excited by a coaxial probe. The theoretical treatment is based on a full-wave analysis and a moment-method calculation. Numerical result s of the resonant frequency, input impedance, voltage standing-wave ra tio (VSWR), and radiation characteristics are presented. It is shown t hat the impedance bandwidth of the spherical annular-ring microstrip a ntenna can be broadened by adding a parasitic disk parch. Compared to the single annular-ring patch case, the spherical annular-ring microst rip antenna with a parasitic disk patch has larger minor lobes and lar ger cross-polarization radiation. (C) 1996 John Wiley & Sons, Inc.