Radar101

Click here to go to our three-page tutorial radar absorbing materials

Click here to go to our page on antennas

Click here to go to our page on phased array antennas

Click here to go to our page on duplexers

Click here to go to our page on Radar Love (new for October 2007!)

What microwave text book could be complete without a discussion of radar basics? None that are worth reading in our estimation. This microwave topic in particular is going to take a long time to get any depth, unless we get some help from the radar industry (hint, hint...)

This just in... we now have a page on the CASA project, an exciting program that will vastly improve our ability to monitor bad weather!

Radar stands for radio detection and ranging, even though its function has been expanded to include range-rate (velocity) measurements. Thanks to Murat for the correction! Radar is one of the few acronyms that is so cool that it is now truly a word, like when Pinocchio becomes a real boy.

=?

Links to sites with outstanding content on radar

Here's a cool web page that provides history of radar!

http://www.vectorsite.net/ttwiz.html

The best website we know of to learn about radar is owned by the NAVAIR Point Mugu:

https://ewhdbks.mugu.navy.mil/

Here's a link to a U.S. Navy website that will provide you with free software for investigating radar propagation in different environments:

http://sunspot.spawar.navy.mil/

History of radar

We have two "radar guys" in our Microwaves101 Hall of Fame! Radar's history goes back farther than you think... Spallazani was the first to investigate how bats are able to "see" using sound waves (sonar).

Christian Andreas Doppler was the mathematician that noticed that objects moving toward or away from an observer shifted their apparent sound frequency. Doppler's work was all done with audio waves, but he postulated that the shift in electromagnetic spectrum would allow astronomers to determine whether stars are approaching or receding Earth (the so-called "red shift" or "blue shift").

The Mark 53 VT fuze was a miniature Doppler radar that helped the Allies target all manner of airborne targets by the end of World War II! Now we have a separate page on the topic!

Types of radar

Monostatic radar
Monostatic implies that the transmit and receive antennas are co-located. Most radar is monostatic.

Bi-static radar
Bistatic means that the transmit and receive antennas are NOT CO-located

Doppler radar
Doppler is used to measure the velocity of a target, due to its Doppler shift. Police radar is a classic example of Doppler radar. The price of Doppler radar has come down recently, so you can buy one for 100 bucks just to play with. We grabbed one of these Bushnell Speedster units from Radio Shack, and found it to have remarkable accuracy, but not much range:

The Unknown Editor's racketball serve was recently clocked at 83 miles per hour!

FMCW radar
Frequency modulated/continuous wave implies that the radar signal is "chirped", or its frequency is varied in time. By varying the frequency in this manner, you can gather both range and velocity information.

Synthetic aperture radar (SAR)
SAR uses a moving platform to "scan" the radar in one or two dimensions. Satellite radar images mostly done using SAR.

Radar range equations

Doppler shift equations

Moved to a new page.

More to come!