Figure 1 Front panel of TR‐3600 Solid‐State Weather Radar Transmitter.
Pulse Systems (PSI) has taken advantage of recent advances in solid-state GaN high-power RF transistor technology to develop the TR-3600 solid-state power amplifier (SSPA) that targets the high-power requirements of weather radar applications. The total amplifier assembly, known as the TR-3600 Solid-State Weather Radar Transmitter and shown in Figure 1, provides a peak output power of 6 kW over a frequency range of 5400 to 5700 MHz. The transmitter can supply this output power at pulse lengths up to 100 μs with the caveat that pulses longer than 6 μs generally require a pulse compression signal processor.
The Pulse Systems TR‐3600 Solid‐State Weather Radar Transmitter is packaged to be compatible in form and fit with the PSI line of magnetron transmitters. This new product offers an easy upgrade or replacement option for any radar using a PSI C‐Band magnetron transmitter. The TR-3600 accepts the same input power connection and trigger connection as the magnetron transmitter. It uses the same ethernet or discrete I/O DB‐37 connection for remote control and status monitoring and the waveguide output is in the same physical position as the magnetron transmitter. The TR-3600 SSPA provides the specified output power from an input RF pulse of 0 dBm nominal power. The receiver used in a magnetron transmitter would need to be modified to add an exciter channel to generate this RF pulse, which is easily done. If the TR‐3600 replaces a klystron-based transmitter, the receiver would already be equipped with this type of exciter. The first TR-3600 has been successfully installed in a local weather radar site operated by a TV station and the solid-state-based radar is exceeding expectations.
There are several advantages to using a solid‐state radar over a conventional magnetron. Some of the main advantages are:
- The maximum voltage used in the SSPA system is 50 VDC. With no high voltages in the SSPA transmitter, there is much less radar maintenance.
- The output peak power is much lower than a magnetron or klystron-based transmitter, so there is no requirement for waveguide pressurization. A pressurizer can still be used to keep the waveguide clean and dry if desired.
- SSPA transmitters can continue to operate with reduced power output when a module fails, while a magnetron failure is catastrophic.
- SSPA transmitters power up instantly, eliminating the warmup time required by magnetrons and klystrons.
- The estimated MTBF for an SSPA transmitter is 250,000 hours versus 3000 hours for a typical magnetron-based transmitter.
- SSPA transmitters provide greater phase stability as compared to magnetron transmitters for better clutter rejection and improved data quality.
- The SSPA transmitter pulse lengths are adjustable up to 200 μs whereas a magnetron transmitter is usually limited to just a few pulse lengths.
Figure 2 Back view of TR‐3600 Solid‐State Weather Radar Transmitter.
KEY SPECIFICATIONS
- 6 kW peak output power, either combined into a single output, or possibly two separate outputs of 3 kW each if used in a non‐power‐split dual polarization configuration.
- Operating frequency is tunable in the range of 5400 to 5700 MHz.
- Pulse lengths up to 100 μs. Pulses longer than 6 μs generally require a pulse compression signal processor. Pulses up to 6 μs do not require pulse compression and offer sensitivity on par with a 1 μs pulse from a 250 kW magnetron or klystron transmitter.
- 10 percent maximum duty cycle, which allows for a 100 μs pulse at 1000 Hz PRF.
- 230 VAC input with 10 Amps maximum current draw, accommodating the same power connector used in the PSI magnetron transmitter.
- The RF input pulse is nominally 0 dBm peak power.
- The same 5 V into the 50 Ω trigger input and the same control/status I/O connection as the PSI magnetron transmitter.
- Touch screen PLC for local control and status monitoring.
- Form‐fit compatible with PSI magnetron transmitter for 19 in. rack mount.
- WR‐187 waveguide output is in the same physical position as the PSI magnetron transmitter in single polarization or split‐power dual polarization. Separate WR‐187 outputs are available if used as non‐split‐power dual polarization (3 kW for each output).
- Forced air cooling. No oil or other liquids are used in cooling or insulating.
- Internal voltages are limited to 50 VDC.
- Graceful output power degradation in the event of failure of an SSPA module.
- Control inputs (local or remote) power on/off, radiate on/off, fault reset.
- Internal fault protection for airflow, over duty, temperature, amplifier fault and VSWR fault. Any fault immediately stops the SSPA output and is latched requiring a local or remote reset to return to operation. Faults and output power can be monitored on a remote interface.
The functional components and architecture of the TR‐3600 Solid‐State Weather Radar Transmitter assembly that goes into the rack are shown in Figure 2.
PSI has nearly 55 years of technical and manufacturing experience in the fields of magnetic components, weather radar subsystems and RF sources. PSI’s flexible and efficient design and manufacturing processes allow them to respond to customer needs and implement new technologies quickly. In addition, extensive production efforts and improvements by Pulse Systems allow these new transmitter systems to be competitively priced with magnetron products, especially considering the dramatically improved lifetime of the solid-state solution. PSI prides itself on proven product durability, quality and performance.
Pulse Systems, Inc.
South Easton, Mass.
www.pulsesystem.com