Broadband bow-tie antenna with tapered balun

ABSTRACT: In microwave applications spectrum Industrial, Scientific and Medical (ISM) band, especially in wireless communication systems applications such as GSM, 3G, Wi-Fi and Wi-MAX applications, high antenna characteristics such as high gain and wide bandwidth are required. In this thesis, a broadband Bow Tie Antenna (BTA) with high performance characteristics has been designed, to cover the wireless application requirements. One of the fundamental problems of the transmission line in the antenna system is the power loss due to the radiation which occurs on the feed excitation. This kind of transmission lines is called Unbalance Transmissions Lines (UTL). To reduce the power radiation on transmissions lines, in other words, to modify transmission line from unbalance to balance (BTL), i.e. UTL-to-BTL transition, the ―balun technique‖ can be used. In this study, for UTL bow tie antenna with Microstip Line (MSL) and coaxial cable feeds have been used. On the other hand for BTL bow tie antenna with Coplanar Strips line (CPS) feed has been used. Two kinds of taper impedance matching techniques have been applied to reduce reflection in the signal. A broadband BTA antenna with dual bands has been designed and simulated having the bandwidth 1.89-3.25 GHz and 3.5-3.67 GHz for operating frequency 2.45 GHz. Maximum gain achieved at 2 GHz which is equal to 6.9 dB and the gain for 2.5 GHz, 3 GHz, and 3.5 GHz, are equal to 4.8 dB, 5.1 dB, and 3.8 dB respectively. Keywords: Broadband Antenna, BTA, bow tie, Wireless Applications, UTL, BTL, Balun, taper, Microstrip line to Coupled Transitions. ………………………………………………………………………………………………………………………………………………………………………………………………………