Parasitic Metal Loading to Purify the Higher-Order Mode of a Cylindrical Dielectric Resonator Antenna

Abstract

The paper shows that a metallic strip placed at certain planes of a Cylindrical Dielectric Resonator Antenna (CDRA) improves the purity of the co-polarized fields of its Higher Order Mode (HOM) when excited by a microstrip line. The metallic boundary suppresses the spurious field components of the HOM which are responsible for a distorted radiation pattern. A directivity of about –30 dB in the broadside direction and about 5.5 dB at ±500 elevation to the broadside has been demonstrated at the HOM frequency of 4.63 GHz. The metal loading also retains the fundamental broadside mode of the CDRA allowing dualband and dual-mode operation.