Reflection coefficient calculation of a feeder structure in a RLSA

Abstract

RLSA(Radial line slot antenna) is slotted waveguide array antenna which is proposed for the DBS(Direct Broadcast from a Satellite) reception. Theoretically, it has lower conduction loss and higher effectiveness than the planar antenna using microstrip. DL-RLSA(Double-layered RLSA) uses radially inward travelling wave for the slot excitation in the double-layered radial line. The effectiveness of DL-RLSA is more than 75%(33.0~37dBi), which is two times as high effectiveness as other planar antenna. In spite of that advantage, SL-RLSA(Single-layered RLSA) is more popular because of the complex structure of DL-RLSA. But the radially outward travelling wave of SL-RLSA makes high tapering when the travelling wave approaches the aperture edge. To remove these troublesome thing, a effective feeder structure which has tilting rod is proposed in this paper. To find the optimum height and tilting angle of the feeder, the finitedifference time-domain(FDTD) method is employed. In other words, the simulation parameter of the FDTD algorithm is the dimension of feeder. Compared with the effectiveness of the conventional rod feeder structure, that of the proposed feeder structure in this paper is enhanced by 5dB.