If you want to measure distances, you must use a pulsed radar. The device emits an EM pulse that goes to the target and is reflected. The radar receiver detects the reflected pulse and the information processing measures the time between emission and reception. This time is twice the distance divided by the speed of light.
Additionally, a pulsed radar has another advantage. The time between pulses is several order of magnitude greater than the pulse duration, so you can have a pulse with a high energy content (and longer range capability), while maintaining the mean power output relatively low.
CW radars are normally used for measuring speeds through the Doppler effect. They are short ranged and cannot measure distances.