Laboratory scale-down experimental set-up is designed and implemented for the measurement of the resonant scattering by an underground cavity in microwave frequencies. Transmitting and receiving dipole antennas of about 3 cm long and 6 mm in diameter are built and yield balanced pattern and the input VSWR less than 3 in the frequency ranges from 5 GHz to 10 GHz.
Transmitting and receiving antennas are 20 cm apart and are moved up and down across the air cylinder with its cross section diameter of 3.4 cm. The total fields scattered by the air cylinder are measured in the 0.75 mm intervals and yield two strong intensity nulls occuring near the air cylinder boundaries at the frequency of 8.3 GHz.
