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• Broadband Cross-shaped Microstrip-fed Slot Antennas
• Broadband Cross-shaped Microstrip-fed Slot Antenna Signal Booster
• Broadband Cross-shaped Microstrip-fed Slot Antenna Tuner

2005 IEEE International Conference on Industrial Technology>287 - 290

Abstract

This CP antenna uses a microstrip-fed rectangular radiator to excite an U-shaped slot. CP wave is generated by two orthogonal E vectors with equal amplitude and 90° phase difference. The broadband CP wave of this antenna is mainly implemented by the U-shaped slot (mode1) and asymmetric feeding structure (mode2). This paper presents a double slot-line–microstrip transition employing a 90° cross over them. Using radial stubs at the crossover between the transmission lines, an insertion loss of less than 1.3 dB was measured (0.65 dB per transition) over the 3–15 GHz range.

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Wang Hong-jian

• Nat. Microwave Remote Sensing Lab., CSSAR, Beijing

Broadband Cross-shaped Microstrip-fed Slot Antennas

Keywords

UHF antennasantenna feedsbroadband antennasfinite difference time-domain analysisgenetic algorithmsmicrostrip antennasslot antennas1.864 to 6.643 GHzFDTDgenetic algorithmfourfold-T-shaped microstrip-fed slotbroadband planar offset antennafinite difference time domainimpedance bandwidthslot patch antennafar-filed patternantennaoffsets

UHF antennasantenna feedsbroadband antennasfinite difference time-domain analysisgenetic algorithmsmicrostrip antennasslot antennas1.864 to 6.643 GHzFDTDgenetic algorithmfourfold-T-shaped microstrip-fed slotbroadband planar offset antennafinite difference time domainimpedance bandwidthslot patch antennafar-filed patternantennaoffsets

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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.

Broadband Cross-shaped Microstrip-fed Slot Antenna Signal Booster

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.

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.

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