This work describes a new single-layer rectangular patch antenna with two pairs of parallel slits designed for dual-band operation. Numerical analyses are presented using the
INTRODUCTIONMicrostrip antennas have been widely used because of their many advantages, such as low profile, compatibility with integrated circuit technology, and conformability to a shaped surface [1, 2]. One of the common methods of feeding a single-layer microstrip antenna is by means of a coaxial probe. When such a method is properly implemented to drive a diagonal-fed nearly square patch antenna, both TM 01 and TM 10 modes are excited and circular polarization is achieved [3]. In this case, the antenna presents a narrow bandwidth. On the other hand, using two feed points at suitable locations, a dual-band linearly polarized antenna can be obtained. However, the linear polarization of the first mode is orthogonal to the polarization of the second one, which may not be acceptable in some applications. Due to this fact, different techniques that present better radiation characteristics have been applied to extend the antenna bandwidth. In [4], a circular patch antenna with embedded reactive loading is studied. A broadband microstrip antenna using genetic algorithm is presented in [5], while an aperture-coupled antenna with parasitic patches stacked on the top of the main element is described in [6]. Recently, it has been shown that wide-band operation can be achieved by using two parallel slits properly designed on a microstrip rectangular patch (E-shaped antenna) [7,8].In this paper, we present a new single-layer rectangular patch antenna with two pairs of parallel slits designed for dual-band
ANTENNA DESIGNAccording to [7,8], the geometry of a wide-band E-shaped antenna consists of a traditional rectangular patch with two parallel slits properly designed in order to expand the bandwidth. Following [9] and using the ENSEMBLE™ CAD tool, an E-shaped antenna with two dielectric layers was primarily designed to cover the frequency range of 1.70 -2.05 GHz, that is, a bandwidth of 18.7% with respect to the center frequency at 1.875 GHz. In this design, the E-shaped patch was printed on a 1.524-mm Arlon CuClad 250 GX dielectric layer ( r ϭ 2.55 Ϯ 0.04 and tg␦ ϭ 0.0022), and a 15.0-mm-thick air layer was positioned between the Arlon substrate and the ground plane, as shown in Figure 1. The length and the width of the slits, as well as the coaxial probe position, were determined in order to achieve a good impedance match in a wide bandwidth. The final patch dimensions and the probe position are given in Figure 1. The simulated results for the VSWR parameter are shown in Figure 2: a bandwidth of 19% considering a VSWR at 1.5:1 was observed. Changes in the dielectric constant, mainly due to substrate tolerance, do not have great effects on the element characteristics because its thickness is thin compared to the air layer under the substrate. Due to the attractive characteristics of the E-shaped antenna, an effort was carried out in order...
