Including the Effects of Curvature in the Cavity Model and New Manufacturing Considerations for Cylindrical Microstrip Antennas

Abstract

This letter presents an insightful and significant improvement of the cylindrical cavity model and an experimental methodology to compensate the mechanical bending effects on cylindrical microstrip antennas. In the first part of this letter, by studying analytical and numerical results from a nonradiating resonant rectangular cavity, a new function for the resonant length of the circumferential mode that is governed by the antenna thickness and cylinder radius was determined. In the second part, an experimental methodology is presented to compensate the copper elongation effect due to bending. To validate the proposed techniques, a circularly polarized rectangular microstrip antenna was designed and built to operate at 2.2 GHz with an input impedance of 50 Ω for a metallic cylinder with a radius of 25 cm. The experimental results showed that the new approaches to calculate the circumferential resonant frequency and elongation effect due to bending improved the cylindrical antenna design significantly.