Effect of Substrate on the Radiation Modes of a Circular Disk Microstrip Antenna

Abstract

The effects of dielectric constant and thickness of substrate on the directional pattern of a circular microstrip disk antenna, excited at higher order modes, is studied theoretically using the stratified dyadic Green s function method based on reflection and transmission matrices. Substrate with dielectric constant ≈ 6 is found to give highest directional gain for 0.1 λ₀ thickness value. It is suggested that the higher order modes such as TM₁₃ mode can be effectively used in antenna arrays by a judicious choice of array synthesis.

Indexing terms:

• Dielectric substrate
• Microstrip disc antenna
• Radiation modes