Dual-frequency planar inverted-F antenna

TLDR

Cellular handsets are increasingly designed for dual‑mode operation, requiring internal antennas for GSM and DCS1800 systems. This paper presents a novel planar dual‑band inverted‑F antenna for cellular handsets that operates at 0.9‑GHz and 1.8‑GHz. The antenna matches conventional size at 0.9‑GHz, achieves >17 dB isolation, bandwidths meet system requirements, works across 1.3–2.4 frequency ratios, supports one or two feeds, and FDTD simulations agree with measurements.

Abstract

Cellular telephone handsets are now being designed to have dual-mode capabilities. In particular, there is a requirement for internal antennas for GSM and DCS1800 systems. This paper describes a novel planar dual-band inverted-F antenna for cellular handsets, which operates at the 0.9-GHz and 1.8-GHz bands. The dual-band antenna has almost the same size as a conventional inverted-F antenna operating at 0.9 GHz and has an isolation between bands of better than 17 dB. The bandwidths of the antenna are close to those required for the above systems. Good dual-band action is also obtained for other frequency ratios in the range of 1.3-2.4. Studies also show that the dual-band antenna can operate with one or two feeds. A finite-difference time-domain analysis has been shown to give calculated results close to those measured.