A Non-Foster UWB Electrically Small Planar Monople Antenna (ESPMA)

Abstract

Electrically small antennas (ESAs) may be employed instead of full-size antennas in a limited space for many communication networks such as the very high-frequency (VHF) band applications and ultra high-frequency (UHF)band applications. However, ESAs can not simultaneously achieve high gain and broadband by passive matching due to the gain-bandwidth theory. This paper presents a ultra wide-band (UWB) transmit electrically small planar monople antenna (ESPMA) with a non-foster impedance matching to bypass the restriction of the gain-bandwidth theory. The proposed antenna is composed of a planar monopole antenna with a height of 10 cm in profile and a non-Foster circuit. The plane monople antenna is chosen because of its better impedance performance than a cylindrical monople. The proposed antenna can operate in the band range of 80 MHz - 500 MHz (145%, VSWR<2.5) much greater than the maximum bandwidth of 0.285% in the theory of matching with the conventional passive circuit. The transmission efficiency of the antenna is improved by as much as 31dB compared with the same antenna without the proposed matching network. Besides, the stability of the proposed matching network is remained within the operating band.