Summary
International Symposium on Antennas and Propagation
2009
Session Number:1A1
Session:
Number:1A1-3
Circularly-Polarized Array Antenna using MSA with Asymmetric T-shaped Slit Loads
S. Kampeephat, P. Krachodnok, M. Uthansakul, R. Wongsan,
pp.9-12
Publication Date:2009/10/21
Online ISSN:2188-5079
Summary:
At present, the advance of wireless systems require an increasment in bandwidth and sharing in limited frequency bands, particularly in PDC (Personal Digital Cellular Telecommunication System), PHS (Personal Handy-Phone System), IMT-2000 (International Mobile Telecommunication-2000), and WLAN (Wireless Local Area Network) [1]. The popular antennas for WLAN access point are linear dipole, slot array, and microstrip antenna. These antennas will be usually placed at the wall of rooms or buildings. Several designs of the single feed dual-band Microstrip Antennas (MSAs) have recently been reported. For example, a dual-band circularly polarized aperture-coupled stacked microstrip patches [2], a spur-line filter-embedded nearly square microstrip patch [3], a circular microstrip patch with two pairs of arc-shaped slots [4], a broad-band U-Shaped PLFA with dual band capability for Bluetooth and WLAN [5], and a square MSA inserted with four T-shaped slits at the patch edges or four Y-shaped slits at the patch corners [6]. The lattermost one proposed a reactively-load technique using four T-shaped slit loads on each patch edge symmetrically. It is small size, low cost, low profile, and light weight compared to the work which are presented in [2]-[4]. Nevertheless, its dual bandwidths of 1.17% and 1.05% are not sufficient to be implemented and was not suggested for utilization in any application. Therefore, Wongsan et al. [7] reported an alternative technique providing dual-frequency wider bandwidth MSA using a rectangular patch and modifying the dimensions of four T-shaped slit loads asymmetrically. Moreover, the thickness of FR4 substrate was increased from 1.6 mm to 3.2 mm in order to enlarge the lower and higher bands of this antenna. However, the antenna has low directive gain and asymmetric radiation pattern. To solve their problem, the high directive gain is presented along with a parametric study based on numerical and experimental results [8]. In addition, the radiation patterns are presented for a modification by alternating the slit loads positions on each side of rectangular patches array configuration. In this paper, we present circularly-polarized array antenna using the rectangular patches with asymmetric T-shaped slit loads. The measured results of the input impedance, return loss, and VSWR are also conducted for verification of the simulated results.