VHF parabolic cylinder antenna for incoherent scatter radar research

A parabolic cylinder reflector antenna has been designed for high-power radar observations of signals scattered from the ionospheric plasma at a frequency of 224 MHz. The antenna is constructed with an offset feed system to reduce aperture blockage. Efficient illumination for circular polarization using crossed dipoles is achieved by means of primary beam forming, which amounts to the construction of a polarization sensitive corner reflector. The measured aperture efficiency is 64%, and the gain 43.6 dB. The antenna can be mechanically steered through 90° in the meridian plane, and the beam can be offset from this plane by ±21.3° by manual phase steering of the 128-element line feed. The width of the aperture is 40 m, and the length 120 m. The reflector is constructed in four 30-m-long sections which can be individually steered. The RF distribution system is such that the two antenna halves can be operated and pointed completely independently. The paper describes the design considerations, the construction, and the testing of the performance of the completed antenna.