Environment

UWB signal propagation measurements were performed in a rural terrain with a bandwidth of 1.3 GHz to characterize the outdoor UWB signal processing channel. The test area is typical of the dense native upper Alabama forest, consisting of southern pines, oaks, cedars, maples, thickets and poison ivy in an area excess of 16 Km2. The multipath propagation channel is frozen during the measurement time by making sure that people in the vicinity of the transmitter and receiving antennas have stopped moving.

Measurements

The measurement system for obtaining the impulse response is shown in a figure below. The test apparatus consists of a periodic pulse generator that transmits UWB radar-like pulses at every 500 nsec using a step recovery diode-based pulser connected to a UWB antenna. A probe antenna was placed near the transmitter's antenna and a fixed length of cable was routed to the receiver for triggering. Therefore all recorded multipath profiles have the same absolute delay reference, and time delay measurements of the signals arriving to the reciever antenna via different propagation paths can be made. The receiver is set in such a way that every 50 nsec window of measurements contains 1024 samples throughout the experiments.

Propagation Losses through foliage and trees

The measurements were made at 'c' feet away from the transmitter and 'd' feet deep into the line of foliage. To generate power delay profile at a predefined position, please select either distance or depth criteria. From the next field, choose the appropriate value of the above selected criteria. Data files related to this experiment can be downloaded from here.