Raditek offers High Power Waveguide Limiters in many narrow bands from 2.6 to 36GHz at peak powers up to 2 Mega Watt in many waveguide and flange sizes.
In addition to high power handling they offer a Low Limiting threshold with a Low Leakage level in a small footprint. They are used as front end protection for Low Noise Amplifiers (LNAs), Power Leveling (Limiting) and Receiver Protection in Radar and EW systems,
These limiters are used to protect weak components such as low noise amplifiers (LNAs) from stray signals. The power transfer characteristic behaves somewhat like an amplifier with just a little loss rather than gain.
These limiters are used most often to protect a low-noise amplifier in a receiver chain. LNAs are carefully designed for low noise figure, and use very sensitive devices to accomplish this; small devices can't handle high input power. Two mechanisms can kill an LNA, heat from the RF input signal, or over-stress due to the RF voltage that appears on the input transistor. Often, an LNA's performance can be changed slightly from high input power, without causing it to fail. Having a damaged LNA might be worse that having a destroyed LNA, you never know when it might fail.
In a radar the stray signal that most likely will damage an LNA come from the transmitter pulsed signal. Damage threshold of an LNA might change somewhat with the duty factor of a pulsed signal, but we recommend that you perform LNA survival testing with CW signals because it is easier, and it will give you a worst case result. One method of evaluating an LNA damage threshold is a stepped stress test.
Flat leakage of a limiter refers to the CW output signal that bleeds through it under high input power conditions. The term "flat" is a misnomer, in real limiters the leakage will have a slope to it at any power level.
Spike leakage refers to the very short part of a high-power pulse that blasts through a limiter, before it clamps down on the signal (there is some delay in turning on PIN diodes). The spike leakage is often referred to in units of energy, not power. For example, if the limiter allows a spike of 1 watt for 10 nanoseconds, the spike leakage would be 10 nano-Joules.
Terminating limiters will attempt to provide an impedance match at any power level. This is a trickier design to pull off than a reflective design, and it won't have as good a response (more insertion loss, or higher flat leakage for example) Plus, you might have to think about sizing the load termination for all the power you might have to dissipate.
A range of our high power waveguide limiters can be seen in the Raditek web site.