Explantion Required for an RF System

I need the explanation of the attached diagram. What is the working principle ?

What is the the delay block? How delay is achieved ?


The diagram is taken from the link.

***.semanticscholar.org/paper/A-Guided-Radar-System-for-Obstacle-Detection-Patfterson-Mackay/8a9776e710a4b0a432c48e4bf3da16f19f986e23

I think delay block is to sync the transmit signal with receive signal to account for time of flight of the signal. For method of delay block, I would assume a circulator may be used. It clearly is a radar detection system, but blocks in it are too ambigious to decide what exactly it does.

Guess: It seems like a I-Q mixer at the receiver end. So, delay block gives a selection between I and Q of mixer, depending on application.

Thanks for reply.

Suppose we have a pair of parallel 100 meter slotted /leaky coaxial cables separated by 2 meters. A spectrum analyzer is attached the one cable and the other end is terminated . The first cable is driven by a continuous 100MHz sine wave. In second case, we drive the cable with 250nSec pulse modulated with 100MHz , and the pulse rate is 50/sec.

What we will observe at the receiving side cable attached to spectrum analyzer and/or spectrum analyzer?