New Compact Antenna Diversity with a Fully Integrated Microwave Circuit for Automotive Satellite Radio Reception

A compact antenna diversity system with a new integrated circuit is presented for automotive reception of satellite digital audio radio services (SDARS) at 2.3 GHz. For a scan-phase antenna diversity with switching and phase alignment of up to three antenna paths, the integrated circuit includes RF switches, phase-alignment and signal combining as well as the frequency conversion for level detection. This is the first integrated circuit for SDARS scan-phase antenna diversity, which includes all the diversity functions except for level detection and digital signal processing. With the integrated circuit with a package size of only 9 mm by 9 mm a compact hardware demonstrator is realized. The diversity circuit is independent of the radio and offers the same interface to the radio as a conventional single antenna. In laboratory measurements characteristic values of the RF signal paths like gain and variable phase shift are determined. In addition, the new compact diversity circuit is also evaluated in a real fading scenario on a single side mirror of the test vehicle showing a significant reduction of audio mutes by the diversity system compared to single antenna reception.