Microwave power modules were developed as compact and highly efficient solutions to replace conventional traveling wave tube amplifiers.
The traveling wave tubes are employed as booster amplifiers in microwave power modules that feature low noise and high efficiency.
Most Ka-band microwave power modules consist of traveling wave tube amplifiers and a high-density switched-mode power supply.
In certain Ka-band microwave power modules, there is a combination of solid-state driver amplifier, power supply, and traveling wave tubes all enclosed in a lightweight package
Microwave power modules are used in radar, navigation, electronic warfare equipment, and communication systems. Most microwave power modules include multi-stage distributed amplifiers in the internal design. They offer high efficiency and can be operated in a wide bandwidth. In certain Ka-band microwave power modules, there is a combination of solid-state driver amplifier, power supply, and traveling wave tubes all enclosed in a lightweight package. In mission-critical applications, the reliability of the system can be related to the operation of microwave power modules.
Microwave Power Modules
There has been consistent growth in communication defense and civilian systems such as radars, microwave test facilities, jammers, and terrestrial or satellite communication systems. All of these applications require medium-power microwave amplifiers. Klystrons, crossed-field amplifiers, and traveling wave tubes are some of the microwave amplifiers that are traditionally used.
In satellite communication systems using conventional traveling wave tube amplifiers, the amplifiers are less efficient. There has been a significant increase in the payload mass due to the number of traveling wave tube amplifiers used.
To reduce the payload mass as well as the overall system cost, modern communication systems and other applications demand compact, highly efficient amplifiers. Microwave power modules were developed as compact and highly efficient solutions to replace conventional traveling wave tube amplifiers.
Microwave power modules bring the best of solid-state amplifiers as well as traveling wave tube amplifiers to modern communication, defense, and commercial systems. The performance of microwave power modules tops the list compared to vacuum-electronic devices and solid-state devices.
Diagram of a microwave power module
The microwave power module consists of the parts given in the block diagram above and a traveling wave tube. The SSPA pre-amplifies the input before the traveling wave tube (TWT) amplifier. The required dBm at the output of the microwave power module is supplied by the two amplifiers. The traveling wave tubes are employed as booster amplifiers that feature low noise and high efficiency.
There is an intermediate block between SSPA and TWT, which can be any one of the following depending on the system requirements: attenuation, temperature compensator, voltage variable attenuator, phase shifter, amplitude modulator, drop-in isolation, gain equalizer, etc.
Applications of Microwave Power Modules
Most common applications of microwave power modules are seen in electronic warfare, missile, or airborne platforms. In both commercial and military radars, microwave power modules are utilized. The test and measurement equipment in microwave applications uses microwave power modules in these systems.
In radars, microwave power modules replace conventional traveling wave tube amplifiers, providing advantages such as:
- Reduced transmission loss
- Elimination of cabling through rotary joints
- Reduction in the cooling systems
- Noise reduction
Microwave power modules are employed in electronic warfare equipment that need to be operated in continuous wave mode as well as pulsed mode. Microwave power modules covering bands ranging from L to Ka frequencies are available.
Let’s use the Ka-band microwave power module as an example.
Ka-Band Microwave Power Module
The Ka-band frequency spectrum is challenging, and microwave power modules need to be designed specifically for Ka-band applications such as radar systems and electronic warfare equipment. The Ka-band microwave power modules operate in the range of 26.54 GHz to 40 GHz. They are capable of operating either in continuous wave mode or pulsed mode with even a 100% duty cycle. The bandwidth of the Ka-band microwave power modules is adjusted for optimizing the power.
Most Ka-band microwave power modules consist of traveling wave tube amplifiers and a high-density switched-mode power supply. The arrangement is popular among Ka-band microwave power modules, as it reduces the hazardous traveling wave tube interconnections as well as the overall size of the system. The integration to the application platform is simplified with this arrangement. Combining the power supply and traveling wave tube together improves the logistics and maintainability.
Ka-Band Microwave Power Modules in Harsh Environments
Ka-band microwave power modules are utilized in applications that are subjected to high humidity, temperature, etc. The packaging of the Ka-band microwave power modules is designed such that they operate normally under harsh conditions.
Cadence AWR Design Environment software can be utilized for designing Ka-band microwave power modules. Cadence software offers tools for the characterization of the module, RF circuit design, and electromagnetic simulation of the interconnects, which shortens the time-to-market of these modules.
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