4.1 Microstrip Antenna for Terminal GNSS Application

As discussed in Chapter 2, the microstrip patch antenna has been successfully modified to radiate a CP wave. Microstrip CP antennas have a compact size for terminal GNSS applications.

There are two kinds of microstrip antennas in terms of the feed: single-feed or multi-feed antennas.

4.1.1 Single-Feed Microstrip GNSS Antennas

The major advantage of single-feed CP microstrip antennas is their simple structure, which does not require an external polariser network. They can be realised more compactly, using less board space than the dual-feed configurations. Many designs of single-feed CP microstrip antennas with square or circular patches have been reported. A corner-truncated square patch printed on an FR4 substrate for RHCP has been discussed in Chapter 2. Other techniques include embedding a cross-slot of unequal arm lengths [1], embedding a Y-shaped slot of unequal arm lengths [2], inserting slits or spur lines at the patch boundary [3, 4], truncating patch corners or tips [5, 6], introducing small peripheral cuts at the boundary of a circular patch [7], addi....