RF Design for Military Radios, Public Safety and Broadcast, and More

~ Helping data and voice signals to reach areas of no coverage ~

There are times when communication is vital, such as on the battlefield or during a state of emergency. Here, Ultralife’s Communications Systems Division explores how the radio frequency (RF) design of amplifiers is a complex but important way to help get important messages delivered.

Radio waves are all around us and utilized in many telecommunications applications. This includes amateur and military radios, public broadcasting systems, smart meters, and satellite communications. Amplifying radio signals allows them to travel farther, which can be invaluable in many of these applications. For example, it can expand data and voice signals from military radios, and public safety and broadcast services, to reach areas that previously had no coverage. This helps soldiers and military vehicles to disperse over a wide area and enhances public service and broadcast connectivity.

There are two main types of RF amplifiers, namely low noise amplifiers (LNA) and power amplifiers (PA). LNA’s are used to receive a low power signal from an antenna and are often found in end use devices such as cell phones and satellite communication downlinks. PA’s, on the other hand, are the amplifiers that are used to boost signals across the no coverage zones so that they are powerful enough to reach the receiver.

Although this sounds straightforward, there are many complex design considerations that go into designing and manufacturing an RF amplifier. Design goals often include gain (a ratio of input to output power), output power, bandwidth, power efficiency, linearity, input and output impedance matching (to help the radio transmitter and antenna work better together), and heat dissipation.

When designing a PA amplifier, working with experienced radio frequency designers – like Ultralife – can ensure it is fit-for-purpose. Such companies use RF simulation tools to provide accurate predictions of amplifier behaviour, allowing designs to be optimized before they are turned into costly physical prototypes. Ultralife use advanced tools such as Keysight ADS Core with EM Design+ Layout and RFPro to create efficient and capable designs.

It is also important to understand which waveforms will be used with the RF amplifier. It could be simple legacy waveforms like FM & AM or modern, complex waveforms like those used in modern MANET and MIMO implementations for tactical battlefield networking. Modern waveforms require improved linearity and timing to achieve their full potential.

Whilst many RF engineers design for the same legacy or modern waveforms, some companies employ the most advanced control techniques available. For instance, Ultralife go beyond typical microcontroller implementation and incorporate FPGA capability to provide increased speed, improved waveform detection, and reduced component count. Ultralife also excel in continuous wave (CW) and frequency hopping capabilities with single-digit microsecond timing.

Amplifiers that are being used by the military may need to be certified to relevant standards, including MIL-STD-461 (electromagnetic capability) and MIL-STD-810 (environmental such as heat, water, dust, and shock resistance), which Ultralife has extensive experience with completing.

To ensure the highest quality products, Ultralife has ISO 9001 certified facilities in Virginia Beach, VA, and Tallahassee, FL, boasting 35,000ft² of combined R&D and production space. In addition to customized RF designs, a range of off-the-shelf amplifiers are also available, including the military-proven 20-Watt A-320V3A lightweight, multiband 30-512 MHz frequency range solution.