臺灣博碩士論文加值系統

在微波積體電路(MICs)中傳輸構造必備之需求為能夠平面化, 能夠平面化
意味著能夠經由其在平面上所佔尺寸的大小而決定其特性o 微帶線路(
Microstrip lines)因為能夠滿足平面化之要求而且容易以光學石版印刷(
photolithographic)術製造,並且擁有相當良好的阻抗分佈範圍
(impedance range)及耦合條件,已廣泛應用於今日的通訊,雷達,以及電子
防衛系統o對於頻率低於26GHz以下,大部份設計都採用純度99.6%(或
99.7%)的氧化鋁基板(介電常數9.8)o但當頻率高於26GHz以上,因為有效波
長變短使得電路尺寸必需縮小,造成製作上更加困難,又因有效波長與有效
介電常數的根號成反比,因此,低介電常數基板的使用可解決此問題 o再
者,由於介電常數的降低,必能加快傳播速度,減少傳播延遲,達到高速化的
要求o在此研究中,堇青石(cordierite)玻璃粉末被用來製成基板(介電常
數:5-6),並以旋轉器(spinner)製造平坦的微帶線路和接地面,以減少衰減
。微帶線路在基板上的性質也被探討。實驗顯示堇青石基板具有良好的特
性,並且適合毫米波微帶線路設計之要求o

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.