TRANSMIT / RECEIVE SUBSYSTEMS BOOST RADIO PERFORMANCE

Transmit / Receive subsystems are important additions to communication systems in which the original transmitter power and receiver sensitivity are insufficient for a new application. A T/ R subsystem situated between a radio and antenna amplifies the radio power in the transmit mode and switches to a preamplifier in the receive mode. Therefore, the communication range is increased by both the gain of the power amplifier and the increased sensitivity of the preamplifier compared to the radio receiver.

For military applications, a T/ R subsystem can improve the performance of communication systems significantly at a fraction of the cost required to replace older radios. Also, a T / R subsystem permits reduction of the transmit and receive antenna radar cross section for constant communication range. For export, a T / R subsystem permits a radio designed with power limitations set by the FCC to transmit with the full power allowed in overseas markets. In the increasingly competitive military, commercial and export markets, customers require high performance, commercial pricing, and little, if any, customization costs.

Since its founding in 1986, LCF Enterprises has offered RF power amplifier modules with high efficiency and small size for both the military and commercial markets. A popular module features 100 W, a gain of typically 10 dB (8 dB min), a frequency of 225 - 400 MHz, and a size of 3.2" x 2.0" x 1.0" excluding mounting feet and connectors. The small size and the high efficiency of 50% typical (40% min) with Class AB linearity simplify embedding the module in a system because power supply and cooling requirements are lower than for less efficient products. LCF has recently developed a modular design for complete T / R subsystems that can be readily configured for specific applications. With a package size of 9.0" x 5.0" x 1.5" excluding heat sink and a weight of 4 lbs, the T / R subsystem fits between a radio and antenna easily in most applications. The modular approach of this system permits the user to configure a subsystem with little, if any, customized costs. As a Commercial - Off - The - Shelf (COTS) product with commercial pricing but proven ruggedness in severe environments, the unit is well suited for both demanding military and commercial applications. With increased transmit power and improved receiver sensitivity, the total radio communications improvement is typically 10 - 20 dB or higher depending on the system.

Paul F. Finman, PhD.

Ó2001 LCF Enterprises