7. Secondary radar degarbling applications

In secondary surveillance radar (RSS), base stations collect information on aircraft in their vicinity, such as their altitude or identity. To do this, the base station transmits a question, in the form of three pulse trains (one in an omnidirectional lobe $\text{Ω}$ and the other two in a directional lobe $\text{Σ}$ ), which is received by special equipment on the aircraft, called a transponder. The transponder then responds automatically.

The difficulty with this system today is that, given the catastrophic increase in air traffic, several aircraft may be in the vicinity of the station and respond at the same time. This problem would be quickly solved if ground station antennas...