A Study of Microstrip Lines on Cordierite Substrate

• Main Authors: Lee-Yee Chen, 陳力毅
• Other Authors: C.C.Wei, C.L.Huang
• Format: Others
• Language: en_US
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/53701559459563985931

碩士 === 國立成功大學 === 電機工程研究所 === 83 === One of the main requirements for a transmission structure to be suitable as a circuit element in microwave integrated circuits( MICs) is that the structure should be planar in configuration.A planar configuration implies that the characteristics of the element can be determined by the dimensions in a single plane. Microstrip line is the most popular transmission line structure that satisfies the requirement of being planar.Ease of fabrication by photolithographic techniques and a good range of impedances and couplings allow it to be used for a wide variety of circuit components.Also, simple transitions to coaxial circuits are feasible.For frequency up to 26 GHz,99.6% alumina substrate (dielectric constant=9.8)has been used by many designers.At higher frequency above 26 GHz,fabrication difficulty becomes significant due to the shorter effective wavelength, which results in the smaller size of the circuit. Since the effective wavelength(and hence the group velocity) is inverse proportional to the square root of the effective dielectric constant,which is closely related to the dielectric constant,a new substrate with lower dielectric constant will solve the problem.Futhermore, the group velocity will also increase when the dielectric constant is reduced. In this work, the cordierite sol-gel glass ceramic powder was used to construct the substrate(dielectric constant : 5-6@1KHz). Basic properties of microstrip lines on cordierite substrate were examined.A comparison to those in alumina substrate is also given. Experiments show that the cordierite substrates have good performance and are suitable for millimetre-wave microstrip designs.