A frequency translator according to the serrodyne principle, for simulating Doppler shifts within 0-400 Hz, is designed, built, and verified. It is based on commercial analog controlled phase shifters. Serrodyne design aspects as well as control signal hardware and software are described. The design is implemented in a multipath propagation simulator for over-the-air tests of car communication. Measurements on the complete multipath propagation simulator verify the performance of the presented frequency translators.
Undesired radiation from common mode currents in cables can be reduced by placing the cable on a ground plane. The chassis of a vehicle often consists of several metal sheets, but two adjacent sheets may not be electrically connected along the whole joint. This paper examines the reduced shielding performance due to various types of gaps between two sheets. A solid connection between two sheets is used as a reference. Numerical simulations in the frequency range 30 MHz to 1 GHz is presented for sheets with a total dimension of 1 meter times 0.5 meter.