radio wave absorbing material
coaxial and balanced strip lines
The matched terminations with medium level of microwave power 10-500 watt and pulsed microwave power 0,2-10 kilowatt for frequency range 1-10 GHz are required as artificial antennas in radar antenna feeder tracts for coaxial and balanced strip lines.
Coaxial terminations in the form of cylindrical resistors cannot ensure required level of microwave power, therefore a bulk absorber needs to be utilized.
There are not any methods of calculation and design of the matched terminations with a bulk absorber in published materials. Heat extraction from a bulk absorber has not been presented yet.
It's required to ensure uniform absorption of microwave power in a bulk absorber and the same heating temperature of the absorber, which must not exceed the permissible one, in order to choose an optimal construction of matched termination with a solid bulk absorber.
The condition is satisfied only if the thickness of a bulk absorber and the square of heat removal from the absorber remain the same along the electromagnetic wave propagation, and the impedance change is made by modifying dimensions of central conductor in transmission line.
The matched terminations with a bulk absorber made of ferrite were tested for frequency range 3 GHz and 1,2 GHz for medium level of microwave power 40 watt and pulsed microwave power 800 watt.
Standing-wave ratio (SWR) did not exceed 1,1. When using liquid cooling, the calculated value for medium level of microwave power was about 500 watt and pulsed microwave power about 10 kilowatt.