Measurement of propagation loss into cars on satellite paths at L-band

Results of 1600 MHz fade measurements into vehicles are presented. The measurements were carried out at J. J. Pickle Research Campus of The University of Texas at Austin. The transmitter used a circularly polarized antenna mounted to a crank-up tower with a maximum height of about 20 in. Elevation angles of 8, 15, 27, 46, 73, and 90' were selected. The receiver used two different antennas (Microstrip Patch and Quadrifilar Helix) mounted to handsets. These were held in a natural way by a person sitting in a car, the Patch at the belt, the Helix at the head. The person holding the antenna was either the driver (alone in the vehicle), or a passenger in the right front or rear seat (driver present). From 8 to 73' elevation, the five cars tested (a small and a large pickup truck, a small and a large sedan, and a minivan) were placed on a turntable 4 inches above pavement and rotated with an angular speed of one revolution in about 72 seconds. At 90' elevation, the receiving antenna was suspended 10 in above the vehicle under test, the transmitter was inside the stationary vehicle, and its subscriber antenna was moved during the measurements. The received signal was sampled at a rate of 1000 sps. Both in- and quadrature-phase voltages were recorded. For calibration, measurements at each elevation angle were also performed outside the vehicle using a known reference antenna. Signal amplitudes were found to be Rayleigh distributed with only a small dependence on elevation angle or vehicle type. The one-second mean signal levels follow a lognormal law. Excess loss is defined as this value minus the median fade observed in open-field rotation measurements for the particular antenna and body position used. Typical excess losses in the vehicles ranged from 3 to 8 dB at the median and from 4 to 13 dB at the 90th percentile.