Waveguide amplifiers are amplifiers specifically designed to be housed within a waveguide assembly. This provides some intrinsic advantages and trade-offs compared with coaxial connectorised amplifier assemblies or pallet amplifiers. Given that waveguide amplifiers are designed to directly mate with a given waveguide size and type, they are innately banded, as the waveguide has a limited frequency range for its preferred mode. The size of a waveguide amplifier assembly directly scales with the operating frequency of the waveguide type, which means that higher-frequency waveguide amplifiers are smaller in size than lower-frequency waveguide amplifiers.
Waveguides offer better power handling capability than coaxial interconnect with lower RF losses, which is why waveguide amplifiers are often used for high power, low noise, small signal energy and other applications where having low losses is ideal. Hence, waveguide amplifiers are common with transmitter subsystems, military communications and test equipment.
Given the relatively large size of low-frequency waveguide amplifiers, millimetre-wave waveguide amplifiers are generally more common, as RF losses tend to increase with increasing frequency. Hence, any steps that can be taken to reduce the RF losses at millimetre-wave frequencies can provide a desirable budget increase for higher-frequency applications.
Other than the waveguide interconnect and feed, waveguide amplifiers are much the same as coaxial connectorised amplifiers. The main difference is that the type of applications that employ waveguide interconnect over coaxial interconnect also have specific needs. These ultimately drive waveguide amplifier design and the trade-offs that are made. This is often military/defence and related applications. Hence, the radar frequency bands designation is often used to describe these amplifiers.
Given that waveguide amplifiers are used in military and defence applications, such as radar and tactical communications, there are waveguide amplifiers available that meet rigorous military standards for reliability and to operate as specified under a variety of environmental conditions. These include altitude, vibration, humidity, shock and wide temperature ranges. Waveguide amplifiers are also often used in space applications and ground station equipment, which have a different and even more stringent requirement for environmental operating conditions and reliability.
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