A small Inverted-F Antenna with adjustable characteristics using lumped elements

Abstract

In this paper, a small inverted-F antenna with adjustable characteristics is proposed with use of lumped elements, capacitor and resistor. Capacitor is inserted between end of the antenna and ground for size reduction and tuning of resonant frequency. On the other hand, 0 Ω resistor is replaced as the short line connected to ground. The movement of short point due to use of 0 Ω resistor results in providing variation of input impedance. Therefore optimum characteristics can be obtained only by proper choice of capacitor and short point without redesign of it's geometry. In order to check the validity, the proposed antenna is designed and fabricated for 2.4 GHz frequency band, and then is applied to a product of Zigbee wireless remote controller. As a result, the size of applied antenna is 8.5 × 4.5 mm2 and it is observed that the measured bandwidth and antenna gain are 150 MHz and 2 dBi respectively without redesign of the antenna.