Azimuthal scattering pattern of trees at X-band

The azimuthal scattering characteristics of a variety of fully foliated trees were measured in the field using a short-range X-band bistatic radar system operating at 9 GHz. Azimuthal measurements were made for both VV and VH polarizations over a 180° angle between the transmitter and receiver antennas at 10° intervals. Data were collected at transmit and receive ranges of approximately 5 m, and the beam impinged horizontally on the trees. The azimuthal power pattern, normalized to the copolarized backscattered power, showed a peak in the forward scattering direction (azimuth angle of 180°) due to direct coherent transmission, whose magnitude was seen to depend on the foliage area density. The diffuse bistatically scattered power in the range of azimuth angles between 10° and 90° showed standard deviations on the order of 4 dB. In addition, needleleaf trees were found to depolarize the incident energy more than the broadleaf trees