DESIGN OF MINIATURIZED QUAD-BAND DUAL-ARM SPIRAL PATCH ANTENNA FOR RFID, WLAN AND WIMAX APPLICATIONS

In this paper, a new design approach is presented for achieving a miniaturized quad-band microstrip patch antenna (MPA) suitable to be used for 915-MHz (UHF band), 2.45- and 5.8-GHz (ISM band), and 3.5-GHz (WiMAX band). The proposed antenna is called modified square spiral antenna (MSSA) which is composed of a modified dual-arm square spiral patch strip structure and a tapered-ground plane with coplanar wave-guide (CPW)-fed configuration to feed this antenna, all printed on the top side of an FR4 substrate. The proposed antenna is designed through intermediate systematic design steps of antennas starting from a conventional strip-fed rectangular MPA and ending by achieving MSSA. A CST Microwave Studio (CST MWS) is used to model the designed antenna, and simulation results, in terms of return loss ([S.sub.11]), realized peak gain and efficiency, besides radiation patterns, are obtained. To validate the design concept, the antenna structure is fabricated, and the simulated and measured [S.sub.11] results nearly coincide with each other. The proposed antenna is characterized by miniaturized size of 28 x 28[mm.sup.2], and based on measured -10-dB [S.sub.11] result, MSSA has four bands, band 1: 915 MHz (872-929 MHz), band 2: 2.45-GHz (2395-2510 MHz), band 3: 3.5-GHz (3470-3550 MHz), and band 4: 5.8-GHz (5698-5900 MHz).