æ–°åž‹é‡‘å±¬å¤©ç·šå¾®å¸¶åŒ¹é å™¨çš„è¨­è¨ˆèˆ‡é–‹ç™¼ - é™¸è»è»å®˜å­¸æ ¡

黃 埔 學 報 第 五 十 三 期 民 國 九 十 六 年
WHAMPOA - An Interdisciplinary Journal 53(2007) 111-114
111
Microstrip Circuitry Impedance Matching Regulator Design for a Simple
Rectangular Metal Radiator in an Antenna
Shen Cherng 1 , Yuan-Tung Cheng 2 , Hsien-Chiao Teng 3
1
Graduate Intitute of Electrical Engineering, Chengshiu University
2
Graduate Intitute of Electronic Engineering, Chengshiu University
3
Department of Electrical Engineering, Chinese Military Academy
Abstract
A microstrip circuit recommended can be used as an impedance matching regulator
for adjusting the VSWR of a loading device. A simple rectangular metal antenna is on the
application of being improved the impedance matching and the antenna gain at specific
operation frequencies. In this article, an equivalent circuit as the result of transmission line
model is proposed.
Key words: SWR , microstrip circuit , equivalent circuit
1. Introduction
Using probing network circuit to
control the function of microstrip antenna
has been discussed a lot [1]. However, the
equivalent circuit created from the
microstrip transmission line model is very
difficult to be constructed due to the
characteristics of the distributed microstrip
elements of the circuit being coupled to the
antenna operated on S band and C band.
The dilemma exists in both Thevenin and
Norton equivalents [2]. We proposed a
circuit with loading device includes two
admittances, one for the load of the
functional microstrip band-pass circuit and
one for the metal radiator [4, 5, 6, 7]. The
microstrip circuit regulates the VSWR to
filter out specific frequency on the bands
and select available operation frequencies.
2. Configuration
Figure 1. shows schematic drawing
of the top view of the proposed microstrip
circuit. The circuit includes three parts
(components), microstrip circuit, connecting
path and a copper metal radiator (metal
antenna). As shown in the figure, the
filter circuit and via path connecting to the
metal radiator can be analyzed by using
transmission line model.
3. Results and Discussion
The proposed antenna is depicted in
Figure 1. The thickness and dielectric
constant of the FR4 plate are indicated d =
0.4 mm, ε
r
= 4.4. Figure 2 depicts the
return loss of the measurement of the
antenna including microstrip strip circuit

112 黃 埔 學 報 第 五 十 三 期 民 國 九 十 六 年
coupled to a major metal radiator as loading
device.
Figure 2. Measurement of the
Return Loss.The impedance
matching of the metal antenna
at 2.85GHz is shown being
improved by coupling to
microstrip circuit regulator
(1)
(A) parameters of the circuit
(B) parameters determined by
neuronet calculation
Figure 1. A microstrip circuit
with loading device.
Figure 3. depicted the prototype of
the design constructed. Figure 4.
demonstrates the field-patterns of the
antenna, including radiator and the
microstrip circuit impedance matching
regulator, that the filter circuit via path being
connected to radiator. The presence of the
forward and backward scattering current
driven by filter circuit delivers the excitation
power via path for the modes of resonances
of the metal radiator. In Figure 5., the gain
of the proposed antenna is depicted. The
filter circuit can improve the impedance
matching and select 2.85 GHz in S band as
well as reducing XPL at elevation plan.
Morover, at other available operating
frequencies, we can observe much better
omnidirectional field pattern and reduced
XPL .(not shown in figure)

Shen Cherng、Yuan Tung Cheng Hsien-Chiao Teng:Microstrip Circuitry Impedance Matching 113
Regulator Design for a Simple Rectangular Metal Radiator in an Antenna
Figure 3. The prototype of the proposed
design constructed
The parameters of the microstrip
lines can be optimized by radial basis
neuronet model. The calculated parameters
are depicted in the following table I.
Figure 5. Gain of the metal antenna
coupling to the proposed microstrip
circuit
Conclusion
Figure 4. The measured radiation
pattern at 2.85GHz
The proposed design of microstrip
filter circuit coupling to metal radiator can
be used to select available frequency-bands
for carrying out specific gain for mobile
system, for instance space shuttle or
WiMAX consideration. Under the
conditions of least XPL, the optional design
of the filter circuit can be performed to
satisfy the specification for the users.
References
Table ( I ) The parameters of the
microstrip lines
unit:mm
(W 1 S 1 ) (W 2 S 2 ) (W 3 S 3 ) (W 4 S 4 ) (W 5 S 5 )
(4,8) (2,1) (6,9) (2,1) (4,8)
[1]. KL Wong, Planar antennas for wireless
communications, Chapter 5~7, John
Wiley & Sons, New York, NY.2003
[2]. JV Bladel, ” On equivalent circuit of a
receiving antenna ,” IEEE Antennas and
Propagation Magazine, vol.44, No.1,
pp164~165, February, 2002
[3]. KL Wong, CH Wu and FS Chang, “A

114 黃 埔 學 報 第 五 十 三 期 民 國 九 十 六 年
compact wideband omnidirectional cross
plate monopole antenna,” Microwave
and Optical Technology Letters, vol.44,
No.6, pp492~494, March 20, 2005
[4]. JP Kim, ”Analysis and equivalent circuit
of aperture-coupled cavity-fed
microstrip patch antenna,” Microwave
and Optical Technology Letters, vol.48,
No.5, pp843~846, May, 2006
[5]. AW Love,” Comment : On equivalent
circuit of a receiving antenna,” IEEE
Antennas and Propagation Magazine,
vol.44, No. 5, pp124~125, October, 2002
[6]. JV Bladel, ” On equivalent circuit of a
receiving antenna ,” IEEE Antennas and
Propagation Magazine, vol.44, No.1,
pp164~165, February, 2002
[7]. TW Chiou and KL Wong, ”Designs of
compact microstrip antennas with a
slotted ground plan,” 2001 IEEE
Antennas Propagat. Soc.Int. Symp. Dig.,
pp732~735
新 型 金 屬 天 線 微 帶 匹 配 器 的 設 計 與 開 發
程 深
1 , 程 遠 東
2 , 鄧 先 巧
3
1
正 修 科 技 大 學 電 機 研 究 所
2
正 修 科 技 大 學 電 子 研 究 所
3
陸 軍 軍 官 學 校 電 機 系
摘 要
利 用 微 帶 線 設 計 濾 波 電 路 , 可 以 用 作 天 線 的 匹 配 器 , 選 擇 想 要 的 操 作 頻 率 與 適 當 的
匹 配 條 件 。 本 篇 論 文 提 出 一 種 簡 單 的 濾 波 電 路 , 可 以 作 為 匹 配 器 , 具 有 良 好 的 選 頻 以
及 調 整 匹 配 SWR 的 功 能 。
關 鍵 字 : SWR, 微 帶 電 路 , 等 效 電 路