Microwave RF Amplifier Boosts Communications Power

April 1, 2008

When you watch TV or use a cell phone, amplifiers make the signal stronger or the voice clearer. A hybrid, high-powered microwave amplifier from Aria Microwave Systems of Teaneck, NJ enables signals to be stronger while offering potential savings to satellite and cell phone system providers. The amplifier also offers a high-power solid-state solution for high-frequency needs in military, radar, industrial, scientific, and medical applications.

Aria’s microwave amplifier generates high levels of power through a synchronous reaction of large numbers of RF semiconductor transistors within the device.

Funded by a Missile Defense Agency (MDA) Small Business Innovation Research (SBIR) Phase II award, Aria's Active Radio Frequency Cavity Amplifier (ARFCA™) provides a unique way of creating a high-power RF amplifier using standard off-the-shelf RF power transistors that are highly reliable and longer-lasting than microwave tubes. By combining the transistors in this way, the ARFCA makes high-power applications like communications far more affordable than current solid-state device-based amplifiers.

Using commercially available amplifier components will allow Aria to manufacture ARFCAs inexpensively and price them to compete with vacuum tube technology minus the short lifespan, and while operating without dangerous high voltages. As a result, applications such as UHF phased-array radar and digital TV transmission can become more practical.

How it Works

Aria's microwave amplifier generates high levels of power through a synchronous reaction of large numbers of RF semiconductor transistors within the device. Because it does not require discrete circuit components, such as capacitors, inductors, and resistors in the RF circuitry, the amplifier also offers greater reliability than not only vacuum-tube-based amplifiers, but commercially available solid-state-based amplifiers, which generally average a six-year lifecycle.

Aria designed the ARFCA to be a simple solution for power amplification — one that flies in the face of the trend to build all modern electronics on printed circuit boards. The design calls for placing a circular disc between cylindrical cavities of an amplifier, onto which are bonded eight or more RF semiconductor transistors. When power reaches the amplifier's output cavity, the transistors begin to react in sync.

The synchronous reaction subsequently generates a high level of power output that is coupled into the device's output cavity and then piped out through standard connectors. This increase in amplitude can be used to boost reliability in telecommunications or satellite operations, or increased output for commercial RF heating.

Several prototypes have been successfully tested for various applications. For cell phone infrastructure, Aria designed an amplifier to operate at 2.1 GHz. This increased power level meets the high peak power required of wide code division multiple access (W-CDMA) and time division multiple access (TDMA) base-station amplifiers. The technology could possibly enable a significant reduction of the number of base stations required to cover a certain area as compared with using high-power, state-of-the-art amplifiers.

An Aria prototype for high-power industrial heating also has shown success in tests. The amplifier operates at 915 MHz, with more than 700 Watts of output power at approximately 1-dB gain compression, which meets the requirements of most industrial applications such as semiconductor manufacturing, plasma processing, and large-scale food processing. Higher power can be attained by using higher-power transistors. Another variant operates at 2.45 GHz and can be used for plasma-fusion lighting. Such lighting, which requires microwave stimulation, is being used to replace conventional high-intensity lights at ballparks, arenas, and factories.

Where it Stands

Aria envisions its patented amplifier technology being used in commercial applications such as cell phone transmission towers, satellite television transmission systems for remote broadcast of events in high definition, and industrial processing units such as RF heaters for chemical processing. The company also is interested in using ARFCAs to enhance output power and reliability of radar as well as other military applications.

More Information

For more information on Aria's microwave RF power amplifier, click here . (Source: MDA TechUpdate, Missile Defense Agency, National Technology Transfer Center Washington Operations)