Effect of Coplanar Waveguide Feedline on Car Roof-Glass Integrated GNSS Antenna Performance

An extension of the feedline is often needed when an antenna is integrated with the roof glass of a car. How much the extension affects the antenna performance depends on the type of antenna and feedline used. This paper studies the effects of coplanar waveguide feedline extension on the performance of a circularly-polarized square slot antenna. Simulation results show a general decrease in the antenna performance with the addition of the feedline. However, the negative effects of the extension on the axial ratio and total efficiency are periodic, indicating that these effects can be mitigated by optimizing the feedline length.