Compact low frequency six-port design for wireless communication devices

In this paper, a compact wide-band direction finding system is proposed that is suitable for wireless handheld and mobile communication devices. The proposed six-port (SP) design covers a low frequency wide band ranging from 1.68 GHz to 2.25 GHz with a bandwidth of almost 570 MHz. This low frequency operation is unique to this design, as most of the available designs cover high frequency bands starting above 2 GHz. The frequency bands covered by this design are for commercially available wireless standards. This includes GSM-1800/GSM-1900/PCS (1850~1990 MHz) and UMTS(1885~2200 MHz) bands. A Major contribution of this optimized design results in 40% reduction in the total area comparing its size with the most relevant design. The dimensions of the optimized SP design are suitable to be accommodated within a software defined radio and cognitive radio platforms. Low frequency RF DF and compact size of this design are the key features. Moreover, the proposed system based on SP design can be extended to a variety of applications and other low cost microwave measurements as well. This SP design is realized on a dielectric substrate area of 65 × 65 × 0.64 mm³.