Terminal GNSS Antennas
In the last few decades, the variety of electronic terminal devices integrated with global positioning, navigation and time services has grown dramatically, so the design of terminal antennas for GNSS applications is attracting more and more interest. This chapter introduces three kinds of RHCP antennas commonly used for GNSS reception, namely microstrip patch antennas, quadrifilar helices and spirals. In addition, a novel PIFA antenna for GNSS application will be presented in the last section of the chapter.
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 , embedding a Y-shaped slot of unequal arm lengths , inserting ...