1880-Hertz Experiment • Maxwell theoretically proved EM waves exist • 1880, Heinrich Hertz- first radar scientist experimentally proved • 450 MHz microwaves fed to dipole • Followed by JC Bose 60- 120 GHz
1939-Varian brothers Klystron• Predecessor of magnetron by Varian brothers of Stanford University• Most important high power radar application device also frequency controllable.
1940-Magnetron • 1930 radar concept given theoretically • Need of high power stransmitter • High frequency radar (3 GHz) for detecting smaller objects • Limitation of high power overcome by magnetron • Frequency depends on dimensions of cavity
What happened during World War-II• 1940-setup of MIT radiation lab for research on application of magnetron for radar.• 4000 personnel aged 20-30 gathered & gained expertise on 100 different radar equipments• Allies gained upper hand over axis powers• Radar was evolved much faster when placed into civilian hands than controlled by military• Today, TWT which is variant of klystron widely used
Other applicationsWeather Radar at Oklahoma Ground penetrating Radar -Seahawk Navigation
Other ApplicationsSpeed measurement Sea Ice Mapping
Microwaves In Modern Radar• Digital signal processing• Differentiate between more than one target• Transmitters The klystron is a good choice for high-power applications, with the TWT (Travelling Wave Tube) as a candidate when wide bandwidth is needed.
Phased Array Radar• Phase array antenna is used in advance radars now a days.• This can form various directional patterns and provide varying directivity.• An advantage of a phased array is its ability to perform multiple functions such as surveillance and weapon control with a single system.