Traditionally, most commercial weather radars employed magnetrons or klystron tubes to generate the high power RF energy. In a solid state radar transmitter, the Radio Frequency (RF) energy is generated and amplified by transistors instead of a vacuum-tube based device. Today’s Solid State amplifiers offer a number of advantages over their tube-based cousins, particularly the lower-cost magnetron. These benefits should be carefully considered when selecting a system, particularly in mobile and portable radar applications.

Magnetrons are generally the lowest cost transmitter solution, particularly at higher frequencies such as X-band. However, the transient oscillation nature of a magnetron results in random phase operation. Pulses from a magnetron are not coherent and require the radar to use “coherent-on-receive” processing, which limits the clutter cancellation ability of the radar and limits some advanced phase-based algorithms for multi-trip echo correction, for example. Fully-coherent radars, such as those using solid-state or klystron transmitters generally have better clutter filtering capability and allow for more varied waveform selection (such as pulse compression waveforms) and pulse repetition interval selection. Moreover, solid-state amplifiers generally can switch pulse widths, frequency, and pulse repetition intervals at a pulse-by-pulse basis.

Magnetron transmitters are generally not frequency agile. Thus, the transmit frequency cannot be easily changed like in a solid-state radar. This can be problematic for mobile radars that may need to avoid particular frequencies for local interference issues. Klystrons allow for some frequency-variability, but are generally narrowband due to the device physics, whereas solid-state amplifiers at X-band may have an operating bandwidth in the hundreds of MHz.

In many weather radar applications portability and ruggedness are key driving factors in the selection of a system. The elimination of tube amplifiers greatly enhances the reliability of the radar, particularly during rough transport, and allows the radar to be operated immediately upon a cold start. In addition, the lifespan of a solid-state transmitter is generally much longer than for a magnetron based transmitter, where the magnetron may need to be replaced after just a few years of operation.

The high voltages required in tube-based radars may also be a concern for many users, particularly those that may need to service their systems in the field.

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