Broadband Cross-shaped Microstrip-fed Slot Antenna
A microstrip-fed cavity-backed slot (CBS) antenna is a slot radiator backed by a rectangular cavity and excited by a microstrip feed line. CBS antennas 12,8,24, 23 are promising candidates used. A broadband microstrip-fed slot antenna is proposed for UHF applications. Its measured impedance bandwidth reaches 85.3% for VSWRles3, covering the frequency range from 390 MHz to 970 MHz. A novel microstrip square-ring slot is merged by cross-slot and fed with a U-shaped tuning stub. The proposed antenna has been designed, simulated, optimized, and measured for the broadband operation. The novel antenna promotes gain, impedance bandwidth, and radiation pattern. Most microstrip-fed structures of the printed slot antenna have been used by making the microstrip-fed struc-tures 5 across the center of slot 7, 8. The conventional cen-ter-fed transverse slot antennas have a large value of radiation impedance, so that it is very difficult to match in practice. The antenna is composed of two pairs of SI slots excited by two orthogonal stepped microstrip feedlines. The broadband characteristic is achieved by combining the fundamental and spurious resonances of the SI slot resonators, while the good cross polarization is mainly due to the introduction of the shorting pins.
Design Ideas for Printed and Microstrip Antennas
Note:
Many of the antennas presented below relate to areas in which a wide variety of patents have been granted.
It should not be assumed that because a technique or physical structure is described here it is free of patents or other commercial Intellectual Property.
They are presented here only for information and educational purposes.
-Ground Plane Effect on Printed Antennas
-Planar Antennas Selection Chart
-Basic Microstrip Antenna Shapes
-Basic Printed Slot Antennas with Feed Structures
-Comparison of Microstrip Patch and Slot Antennas
A numerical simulation and an experimental implementation of T-shaped microstrip-fed printed slot array antenna are presented in this paper. The proposed antenna with relative permittivity 4.3 and thickness 1.0mm is analyzed by the finite-difference time-d
tation of T-shaped microstrip-fed printed slot array an-tenna are presented in this paper. The proposed antenna
with relative permittivity 4.3 and thickness 1.0mm is ana-lyzed by the finite-difference time-domain (FDTD) method. The dependence of design parameters on the bandwidth characteristics is investigated. The measured bandwidth of twin-slot array antenna is from 1.37 GHz to 2.388 GHz, which is approximately 53.9 % for return loss less than or equal to -10 dB. The bandwidth of twin-slot is about 1.06 % larger than that of single-slot antenna. The meas-ured results are in good agreement with the FDTD results.
As microwave equipments require low profile and light-weight to assure reliability, an antenna with these characteris-tics is essentially required and a microstrip antenna satisfies such requirement. Microstrip antennas have conformal struc-ture, low cost, and ease of integration with solid-state devices as well as low profile and lightweight. But the microstrip an-tennas have a narrow bandwidth which is about 10-20 %. In the last decade, many researchers have studied the bandwidth widening technique of microstrip antennas [1]-[3]. A popular method is the use of parasitic patches, either in another layer (stacked geometry) [4] or in the same layer (coplanar geome-try). However, the stacked geometry has the disadvantage of increasing the thickness of the antenna, and the coplanar ge-ometry has the disadvantage of increasing the lateral size of the antenna [5]. Most microstrip-fed structures of the printed slot antenna have been used by making the microstrip-fed struc-tures [5] across the center of slot [7], [8]. The conventional cen-ter-fed transverse slot antennas have a large value of radiation impedance, so that it is very difficult to match in practice. To solve these problems, short-tuning and open-tuning stubs which offset from the center of a slot to the end were proposed [9]. Narrow slot width is good for impedance matching [10] but with wide slot width, a special matching circuit at the feed-ing port is needed for good impedance matching.
Broadband Cross-shaped Microstrip-fed Slot Antennas
This paper presents the characteristics of single-slot and twin-slot antennas with T-shaped feed line. A T-shaped micro-strip feed line is proposed to match the input impedance for narrow as well as wide slot antennas. When the T-shaped feed line is used, we can extend the bandwidth in proportion to the slot width. In this case, the proposed antenna leads to the im-
Manuscript received August 18, 2000; revised February 16, 2001.
Broadband Cross-shaped Microstrip-fed Slot Antenna Booster
Yong-Woong Jang is with the Department of Electronic Communication Engineering, Keukdong College, Chungcheongbuk-Do, Korea. (phone:+82 43 881 3317, e-mail: ywchang@telecom.kdc.ac.kr)
Broadband Cross-shaped Microstrip-fed Slot Antenna Tuner
ETRI Journal, Volume 23, Number 1, March 2001 Yong-Woong Jang 33