Abstract-In this paper, a simple design of wideband rectangular patch antenna is presented by using asymmetrical feed and a reduction in ground plane with proper gap distance. The frequency-dependent characteristic impedance included in the proposed procedure is addressed to eliminate possible errors in the high-frequency broadband applications. The antenna proposed in this research provides 2.3GHz bandwidth (frequency range: 0.9GHz -3.2GHz) which can be utilized in various broadband applications such as remote sensing, biomedical and mobile radio. The proposed procedure in this research is compatible with CAD applications and is valuable contribution as it permits quick and easy design for RF engineers.Index Terms-Microstrip, broadband, frequency-dependent, CAD.
I. INTRODUCTIONIn mobile communication antenna design, the antenna has become an integral part of the mobile devices. To achieve this goal, the antenna for mobile sets must be small, flexible, and efficient. Rectangular microstrip patch antenna is one of the most utilized antennas because of its low cost, low profile and omnidirectional radiation pattern. A narrow bandwidth and low gain are main drawback of this antenna [1]. Higher bandwidth is desired in various applications such as remote sensing, biomedical, mobile radio, satellite communications etc. In order to improve the bandwidth, intensive research has been carried out and several techniques are proposed."The conventional methods for broadening impendence bandwidth are the following: modified shapes of the radiation element, partial ground plane feeding structure, inserting capacitor between the patch and the ground plane, inserting chip resistor between the patch and the ground plane, inserting a chip inductor " [1].However, most of these antenna designs are either too complex or impractical for practical applications in GHz frequency range. The difficulty in designing a simple and compact antenna with broadband or multiband functions is still a challenge for engineers since the complexity and size of the antenna's structure is reduced and the operating frequency bands increase. As mentioned earlier, there is extensive literature that presented the design of broadband Manuscript received March 5, 2014; revised May 14, 2014
II. MICROSTRIP ANTENNA DESIGNMicrostrip antenna consists of dielectric substrate located between the radiation patch on top and ground plane on other side as illustrated in Fig. 1.The patch is made using conducting materials like copper and gold and can be made into any shape. However, the radiating patch and feed line is etched on dielectric substrate [4]. For simplicity of analysis, the patch is generally square, rectangular, circular, triangular, and elliptical or some other common shape. For a rectangular patch, the length of the patch is usually in the range of 0.3333 0 < < 0.5 0 , where 0 is the free space wavelength. The patch is selected to be very thin such that ≪ 0 (where is the patch thickness). The height of the substrate is usually 0.003 0 ≤ ≤ 0.05 0 . The diel...