Continuous Wave Radar with non zero Intermediate frequency:
The main disadvantage of normal continuous wave radar is that same antenna is used for transmission and reception. The continuous wave radar with non zero IF provides isolation between transmitter and receiver. Separate antennas are used for transmission and reception to reduce the signal leakage. Local Oscillator provides the carrier signal whose frequency is equal to intermediate frequency. The transmitted signal along with the locally generated signal is modulated inside a mixer. The output of the mixer is a signal consisting of sum components of frequency and difference components of frequency. The signal is then passed through a side band filter which removes the effect of noise and reduces the receiver sensitivity.
The output of the side band filter is fed onto a receiver mixer where the Doppler frequency is added along with the original frequency of the signal. The Doppler frequency can be positive or negative depending on the location of the target. The output of the receiver mixer is then amplified and passed onto a detector. The detector removes the IF component from the received signal and passes only the doppler frequency component. The doppler frequency component is then amplified by a doppler amplifier. The output of the doppler amplifier is fed onto an indicator which provides the location of the target depending on the value of doppler frequency.
The block diagram of Continuous Wave Radar with non zero Intermediate Frequency is shown below.