A Compact Monopulse Radial Line Slot Array Antenna at Millimeter Wavelengths
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A Compact Monopulse Radial Line Slot Array Antenna at Millimeter Wavelengths Lizhi You & W. B. Dou
Received: 17 December 2006 / Accepted: 27 June 2007 / Published online: 21 July 2007 # Springer Science + Business Media, LLC 2007
Abstract This paper describes the design and performance of a radial line slot array antenna (RLSA) which generates sum or difference far field patterns. The antenna consists of rectangular waveguide to radial line transition, radial line and slot arrays etched on the upper plate of the radial line. A novel rectangular waveguide to radial line transition is designed to build up the dominate TEM mode in radial line to excite the slot arrays which are arranged in concentric rings on the upper plate of the radial line. The antenna radiates linear polarization at Ka band. Monopulse operation is obtained by a sum and difference network which is a compact eight-port comparator consisting of coplanar magic tees. The sum and difference network is waveguide structure whose loss is less than that of microstrip structure at millimeter wave lengths. The monopulse performances can be used in monopulse tracking and anti-collision application etc. Genetic algorithm (GA) is applied to optimize the parameters of the transition and antenna to obtain good performances. Keywords Monopulse radial line slot array antenna . Rectangular waveguide to radial line transition . Coplanar magic tee . Millimeter wave 1 Introduction In millimeter wave band, fabrication of rectangular waveguide slot arrays becomes difficult as the frequency increases because the physical size of the waveguide is small. High accuracy in manufacturing is needed which results in high cost. Furthermore, it is difficult to arrange the slot arrays on the rectangular waveguide walls precisely in fabrication at millimeter wave band, which affects the performances of the arrays directly. Under these circumstances, radial line slot arrays become more attractive because all slots are fabricated or etched on the upper plate of one radial line, which results in low cost and easiness to Note: Part of this paper has been presented in the oral session ThuA5 on Transmission Lines and Antennas in IRMMW-THz2006 Conference, pages: 535. Number: 376636 Title: Radial line slot array antenna at millimeter wave lengths L. You : W. B. Dou (*) State Key Lab of Millimeter Waves, Southeast University, Nanjing 210096, People’s Republic of China e-mail: [email protected]
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Int J Infrared Milli Waves (2007) 28:811–820
control the excitation. The radial line slot array antennas (RLSA) have been developed for microwave and millimeter-wave applications in recent years for its high efficiency and easiness to fabricate. Work using this type of antenna can be traced to Kelly and Goebels, who had successfully obtained arbitrary polarization RLSA antennas [1] and monopulse RLSA antenna [2] early in 1960s. It was further developed in Japan, Australia and Spain etc. for receiving DBS TV and other applications [3–11]. Several studies on RLSA have been developed for monopulse
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