Transmission line model design formula for microstrip antennas with slots

A technique, based on the transmission line model, for the analysis of a rectangular microstrip antenna, in which more than one slot have been embedded in its non-radiating edges, is presented. Using this method, the number and the dimensions of the slots in a microstrip antenna can be calculated, in order to get a desired lower resonant frequency from a much smaller patch than the initial rectangular one.

1. INTRODUCTION

Microstrip antennas are widely used due to their low profile, light weight and conformal nature. In addition, modem applications demand smaller antenna sizes than the usual of a half wavelength, making the miniaturization process a challenging field. One of the most commonly used methods to miniaturize a microstrip antenna is by increasing its electrical length. This technique can be implemented by embedding slots in the non-radiating edges. In practice, this technique has led to two well known types of microstrip antennas, the H-shaped and the meander patches [1], [2].