Alternative antenna polarization schemes for satellite-handset links including operator tissue

A major goal of personal communications networks and services is to provide seamless, ubiquitous wireless communications to the user. For the last few years, several providers have pushed to develop and deploy low-earth orbit satellite constellations which are intended to play a major role in providing this desired world-wide coverage. However, it has recently become evident that the design of a transceiver handset which can link with the satellite network as well as the existing cellular infrastructure presents some challenges. This is particularly true of the antenna, which must provide linearly polarized (LP) isotropic coverage at the cellular frequency band and circularly polarized (CP) hemispherical coverage at two distinct satellite bands. The design of such an antenna is complicated by the fact that the user tissue can significantly degrade the antenna radiation characteristics, particularly for CP elements. It appears that several different approaches are under consideration by antenna designers to deal with the tissue-induced pattern degradation. For example, one concept involves simply using a CP element or even a LP element on the handset, and making up for the induced losses by increasing the system gain elsewhere. Other concepts, proposed by those wishing to optimize the link budget, include designing CP antennas which are insensitive to the tissue presence (which proves very difficult), or perhaps using antenna polarization diversity combining to optimize the received signal at the handset. In this paper, we explore the use of CP, LP, and diversity elements (with equal gain and selection combining schemes) and quantify through simulation the performance of each configuration when operated near human tissue.