Reduction of Cavity Resonance In Wireless Applications

Abstract

This paper presents a radio-frequency (RF) evanescent-mode cavity resonator for passive wireless sensor applications. The evanescent-mode resonator is composed of a cavity with a center post. The resonant frequency of the resonator is determined by the dimension of the cavity, the gap between top membrane electrode of the cavity, and the center post. I. INTRODUCTION Printed circuit-board design has become quite complicated these days. one reason for this phenomenon is the increase in availability of commercial applications, many of which are wireless in nature. such applications have increased clock and processor speeds, and therefore emit higher frequencies. unfortunately, the higher frequencies often lead to a number of critical challenges for the designer- not the least of which is reducing and eliminating cavity resonance. commercial applications like consumer electronics, notebook computers, wireless lan devices, network servers and switches, wireless antenna systems, and cellular base stations are especially vulnerable to this problem. microwave absorbing now provide designers with a viable method of eliminating both simple and complex cavity resonances. microwave offer a proven method for reducing or eliminating resonance. both magnetically and dielectrically loaded can be used. microwave cavities have certain resonant frequencies that oscillate. microwave-absorbing are a demonstrated, viable method for eliminating both simple and complex cavity resonances. the energy can be attenuated when lossy magnetic or dielectric are introduced into the cavity. however, less-expensive dielectrically loaded foam despite their thickness and conductivity, can also help safeguard circuit boards. either approach can eliminate cavity resonances. II. HEADING S Inside a material matrix. The filler consists of one or more constituents that do most of the absorbing. The matrix material is chosen for its physical properties (temperature resistance, weatherability, etc.). Absorbers are characterized by their electric permittivity and magnetic permeability. The permittivity is a measure of the materials effect on the electric field in the electromagnetic wave and the permeability is a measure of the materials effect on the magnetic component of the wave. The permittivity is complex and is generally written as