BROADBAND DUAL-MODE SLOT ANTENNA

摘要

A novel cavity-backed 4-arm slot spiral antenna for broadband communications is proposed in this paper. It is designed for dual-mode, 1st/Normal mode and 2nd/Split-Beam mode, operation from 1.5-4.5GHz and 2.5-6GHz respectively. A Finite-Element Boundary-Integral (FE-BI) based numerical tool is extensively used to study effects of various antenna parameters, including slot width, dielectric loading, cavity depth, growth rate, resistive taper, etc. The slot spiral is designed for axial ratio ≤ 4dB over the desired bandwidth for both modes. Based on the numerical analysis, cavity depth and diameter of 1.5cm and 8.5cm, respectively, were chosen. The antenna is built on a 0.0786cm thick RT/Duroid~R5880 substrate of dielectric constant (ε_r) 2.2. Measured and numerical data are presented and discussed, and generally a very good agreement between the two is obtained.