International Symposium on Antennas and Propagation
BOR-SPR Antenna with a Stop Band
H. Nakano, M. Baiju, J. Yamauchi,
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The input impedance of a conducting body of revolution (BOR) above a ground plane has a wideband frequency response. The lower edge of the operating frequency band of the BOR depends on the height of the BOR. Recently, we added a parasitic ring  to a BOR, whose height is extremely small (0.07 wavelength at lower band edge ), and found that this antenna, designated as the BOR-SPR (abbreviation for BOR with a shorted parasitic ring), has a 148% bandwidth for a VSWR = 2 criterion. This paper is a sequel to the research on the BOR-SPR found in  and presents a technique for generating a stop band in the frequency response of the VSWR . Such a stop band is effective in reducing interference with nearby devices, or enhancing the isolation of transmitted signals from received signals . The stop band in this paper is generated by adding a conducting line to each of the four pins that connect the parasitic ring to the ground plane. This conducting line (of length lL) is located parallel to the pin, with spacing sL. The analysis of this BOR-SPR is performed using the finite-difference time-domain method (FDTDM) . The effects of the length lL and spacing sL on the stop band are analyzed and the center frequency and width of the stop band are discussed. Note that the radiation pattern is also analyzed and discussed.