Design considerations of a broad band microstrip antenna with embedded negative capacitor loading

Abstract

In this article, effects of negative capacitor loading on the bandwidth (BW) and efficiency of a rectangular microstrip antenna (RMSA) have been investigated. The active negative capacitor is made of a field‐effect transistor that exhibits negative resistance as well as capacitance. It can, therefore, compensate the loss of an inductor having antenna. A single negative‐capacitor‐loaded RMSA gives broadband frequency operation with broadband radiation. A microstrip patch operating at 10.5 GHz having 12.22% BW has been utilized as a reference antenna. Theoretical results for the impedance and the radiation patterns have been presented. It is also shown that the impedance BW of the antenna has been enhanced by using active negative capacitance networks from 12.22% to 16.96%, respectively. In addition, it has been shown that active compensation significantly improves the radiation pattern. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2651–2656, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22806