Design of a triband microstrip filter for GPS receiver

Global Navigation Satellite System (GNSS) receivers provide users with positioning, velocity and time. These receivers have to work with different standards and frequency bands in order to enhance the precision and the robustness. A multiband GNSS terminal with a single RF front-end would be a beneficial and cost-effective solution that allows the combination of more than two bands. The RF filter is an important component in the radio receiver. In this paper, we focus on the design of a tri-band filter operating at the three frequency bands (L5, L2, L1) of the GPS standard. The filter schematic is based on the half-wavelength bandpass topology with crossed open stubs. S parameters simulations show good agreement between the filter response and the standard specifications in terms of center frequencies and bandwidths.