Applications of Planar Multiple-Slot Antennas for Impedance Control and Analysis Using FDTD with Ber - Antennas and Propagation Society International Symposium, 1995. AP-S. Digest

Foldedand multiple-slot antennas have been used for quasi-optical arrays. However, there is lack of information of these antennas, especially on finite substrates. In this paper, CPW-fed foldedand multiple-slot antennas are analyzed using FDTD technique with improved absorbing boundary condition (PML method). The effects on the effective dielectric constant and input impedance due to substrate thickness have been investigated. Furthermore, a method of controlling the resonant impedance will be presented in the conference. CPW-fed folded and multiple slots have been used in quasi-optical amplifier arrays [1],[2]. These antennas are chosen because of their simple fabrication, easy integration with threeterminal devices, and broader bandwidth compared to other planar antennas, such as patch antennas. However, little design information [3]-[5) is available for these antennas on dielectric substrates, such as resonant frequencies and input impedances, which are essential to circuit designs. This paper presents a numerical investigation of the foldedand multiple-slot antennas using the finite difference time-domain (FDTD) technique with PML absorbing boundary condition [G],[7]. The influence of antenna layout and substrate parameters on the input impedances and resonant frequencies of the antennas will be described in this paper. In addition, a method of controlling impedances of these antennas will be discussed. Using this technique, we are able to obtain a large range of impedance values at resonance. In particular, a five-slot antenna with 50 R input impedance has been built and tested. This antenna will play an important role in developing quasi-optical system since it can be integrated directly with commercial MMIC chips without any matching networks.