For electronic warfare and electronic countermeasures simulation, radar cross section measurements and other military applications requiring high RF power, dB Control has developed a 4 kW nominal, 7.5 to 18 GHz traveling wave tube amplifier (TWTA). With a 50 μs pulse and 100 kHz maximum pulse repetition frequency, i.e., 5 percent duty cycle, the dB-3911 provides 3.4 kW saturated output power across 7.5 to 11 GHz, 4 kW from 11 to 17 GHz and 3.4 kW from 17 to 18 GHz. The TWTA is not restricted to pulsed signals; it can amplify CW, AM, FM and pulse-modulated signals.
The dB-3911 TWTA achieves this high saturated output by combining two periodic permanent magnet TWTs. Power combining losses are minimized by phase matching the TWTs and other RF components over the entire frequency range. The dual TWT design improves harmonic performance, typically –10 dBc. Spurs are –50 dBc within 1 MHz of the carrier.
The single RF input is via a female type N connector, and the output uses a WRD750 flange waveguide. Forward and reflected power can be monitored using the sampled output connections. The dB-3911 is powered with a single phase 220 VAC connection and consumes a maximum of 3 kVA. The TWTA is 18 in. (w) × 36 in (d) × 21 in. (h), and weighs 175 lb.
The amplifier and power supply have built-in protection from excessive helix current, over/under voltage, high VSWR, arcing and temperatures outside the operating range of –20°C to +50°C. The front panel has an on/off switch and display showing the operating status and any faults. As an option, the TWTA can be controlled remotely using RS232, RS422, RS485, Ethernet or a custom protocol.
Established in 1990, dB Control designs and manufactures high-power TWTAs, microwave power modules, transmitters and high voltage power supplies, supplying them to military organizations, major defense contractors and commercial manufacturers.
Original article appeared at: http://www.microwavejournal.com/articles/31328-kw-75-to-18-ghz-dual-tube-twta