An ultra low power, long range, robust radar system, for applications such as ionospheric sounding. The HF transmit signal and the received (reflected) signal are both unswitched and high frequency and share a path to a common loop antenna. The transmit signal originates at a local oscillator (LO), and is sufficiently low power to not saturate the receive signal path. A balun divides the local oscillator signal between the transmit path forward to the antenna and a mixer path, and also divides the received signal between the mixer path and the LO path. A mixer converts the mixed LO and received signal to baseband.
Rodney V. Landreth; William D. Davis; Robert W. Robison