I have been wanting to dabble in the world of RF, I have not done an RF design before and thought it would be an interesting way of understanding more with a practical application. The best way to do something is always by trial and application.

There is a certain amount of base knowledge I knew that was required before diving straight into a design and that was well what is a radar? A google search yields "A system for detecting the presence, direction, distance, and speed of aircrafts, ships, and other objects, by sending out pulses of radio waves which are reflected off the object back to the source"

There had to be a start to break down the parts of a radar. Looking at Continuous Wave (CW) radars, these transmit a constant frequency signal and simultaneously receive the refelected echo scattered from objects continuously. These types are typically used in compact, short-range, low-cost applications. CW Radars can utilise any part of the Radio Frequency (RF) electromagnetic spectrum. An Unmodulated CW Radar continuously transmits a pure tone such as a sine wave, which is the carrier. The echo is the received scattered from objects. All simultaneously. By doing so, we measure the Doppler Shift from a moving object. Doppler shift is the change in a wave's frequency and wavelength due to relative motion between the waves source and observer.

An example of this is an ambulance's siren, the pitch rises as it approaches and falls as it moves away. When moving toward's you, the waves compress (higher frequency) and when moving away they stretch (lower frequency). If a target / object is static, the frequency of the echo signal is unchanged from that transmitted. If the target / object is moving the frequency of the echo is altered due to the Doppler effect. This Doppler frequency is how the object's motion can be determined.

The faster the object moves in a given direction, the larger the Doppler frequency.

F_D = 2Vr/λ

where,

Vr = Radial velocity of the object (m/s)
λ = Wavelength of the CW signal (m)
F_D = Doppler frequency (Hz)