1.

1. An over-the-horizon backscatter radar has its receiver facility located 40 km from the transmitter facility and at right angles to the transmit antenna s boresight. The transmit and receive beams scan 30 simultaneously. Both are unweighted apertures of 20 dB gain in azimuth and 6 dB in elevation at 30 MHz. At that frequency, what is the approximate isolation afforded by the geographic separation of the two facilities? [Hint: Consider a flat Earth. Assume the sidelobe antenna gain is 1/100 ( 20 dB) of the main-beam antenna gain.]

2. The system employs an unweighted FM/CW waveform using an FM ramp of 10 ?sec duration with a bandwidth of ? = 1 MHz. The minimum range is 740 km. What additional isolation is afforded by this waveform? (Hint: Assume waveform time sidelobes are [sin( x/ x)] ².)

3. If the effective radiated power of the OTH-B system were 80 dBW, what signal level direct from the transmitter would enter the receiver front end?

4. Would appear in the first range bin (740 km) at the output of the FM/ CW processor?

5. A 10-m ² target at 740 km range would enter the receiver at 133 dBW, assuming 1/ R ⁴ attenuation, and would appear at the processor output at about 10 dB below the transmitter power. What are your comments about the need for additional suppression of the direct transmitter signal?

2.

1. Design a pulse-Doppler waveform for a transmitted frequency