Radar Systems for Technicians
Combining historical insight and technical information, this text takes the reader as far back as original World War II concepts to illustrate the logical reasoning behind state-of-the-art radar designs.
TABLE OF CONTENTS Radar Systems for Technicians
The Modulator
At one time, pulsed radar modulators were so similar, that, once a technician gained a thorough understanding of the modulator in one system, nearly all others were so similar, that his main task in becoming familiar with a new system was only to learn the location of components, and note design variations. As radar design evolved into larger and more powerful transmitters, and as designers attempted to eliminate the high-failure components in the modulators, new and different concepts appeared. Given the target size of this book and chapter, and the variety of modulator types now in use, it is necessary to limit this discussion to the original and fundamental design, with only brief mention of others.
The Requirements
In a magnetron system, the magnetron will oscillate, as long as the negative-going, high-Voltage, pulse remains on the cathode. Obviously, then, the presence of high Voltage on the tube at times other than the main bang is unacceptable. It would also be unacceptable, in the case of the amplitron, because of the high-power noise that would be emitted. In the case of the power klystron, emission is negligible, in the absence of drive; but continual application of dc Voltage would cause excessive average body and collector currents, overheating and damaging the tube. So, in all pulsed-radar cases, the transmitter power amplifier tube requires a high-Voltage pulse, and continuous d-c is unacceptable.
Beyond the requirements of the high-power tubes, the high Voltages and currents necessary for the modulating pulse give rise...
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