Pulse Width and Bandwidth: Some radar transmitters do not transmit constant, uninterrupted electromagnetic waves. Instead, they transmit rhythmic pulses of EM waves with a set amount of time in between each pulse. The pulse itself would consist of an EM wave of several wavelengths with some dead time after it in which there are no transmissions. The time between each pulse is called the pulse repetition time (PRT) and the number of pulses transmitted in one second is called the pulse repetition frequency (PRF). The time taken for each pulse to be transmitted is called thepulse width (PW) or pulse duration. Typically they can be around 0.1 microseconds long for penetrating radars or 10-50 microseconds long for imaging radars (a microsecond is a millionth of a second). In math language, the above can be said... PRT = 1 / PRF or PRF = 1 / PRT And for all you visual learners out there, this is what it looks like... RT means repetition time. However, the above diagram is not quite realistic for several reasons. One reason why it is not realistic is that the frequency in waves of the pulses are the same. In real life the frequency of the waves are not the same and they change as time goes on. This is called frequency modulation which means the frequency changes or modulates. It looks something like this... Think of this as one pulse. All the pulses will look something like this. On the above diagram, the frequency of the wave is low on the left and it slowly increases as you look right. The different frequencies of the wave will lie in a range called bandwidth. Radars use bandwidth for several reasons regarding the resolution of a data image, memory of the radar and overuse of the transmitter. For instance, a high bandwidth can yield a finer resolution but take up more memory. | 
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