| 16 Mar 2026
Magnetron or SSPA for weather radars? Evaluation of the data quality of a dual transmitter setup
Abstract. This paper describes the data quality of the first weather radar with a solid state power amplifier (SSPA) in use at the German Meteorological Service. The new transmitter has been integrated into the existing C-Band radar at the Observatory Hohenpeissenberg in October 2023. The resulting setup is unique: most of the radar hardware (wave guides, pedestal, antenna, radome) is shared between the magnetron and solid state transmitters. The same weather situation can therefore be observed with both transmitter types with a small time difference of around five minutes, while most elements of uncertainty from the hardware can be disregarded for their comparison. A two pulse scheme is investigated with an un-modulated short pulse and a long pulse with non-linear frequency modulation. The scheme provides similar spatial resolution compared to the magnetron system. We show the results of the comparison of the data from both transmitters, focusing on reflectivity, Doppler moments and dual-polarization data. Magnetron and SSPA transmitters provide comparable data quality in areas with a signal-to-noise ratio (SNR) >20 dB. For lower SNR, the SSPA outperforms the magnetron transmitter. This is especially noticeable in ranges above 130 km from the radar. Data at the transition between the modulated long pulse and the un-modulated gap filler short pulse are investigated in detail. It is shown that the matching works well and a simple approach with fixed offsets is sufficient to provide a smooth transition. Range sidelobes are investigated with examples originating from strong clutter targets and an intense convective cell. For targets stronger than 55 dBZ, range sidelobes reach levels in many radar moments (including dual-polarization moments) that resemble meteorological echoes. They influence the whole length of the pulse (30 km in the presented case). The effect on radar products and possible mitigation approaches still have to be investigated. In general, SSPA transmitters for weather radars are assessed as viable in terms of data quality and are considered as an option to replace magnetron transmitters in the DWD weather radar network.
The manuscript is noteworthy but the technical discussions should be clarified. There is a blurring of the concepts of,
1) coherency
2) phase noise
3) SNR after pulse compression
4) spatial smooth
5) sensitivity versus SNR
For example if a SSPA and a magnetron transmit the same energy, the SNRs (after pulse compression) should be about the same. Theoretically, they are the same.
Even though a magnetron is a incoherent transmitter, the transmit phase is measured and the received signal is the made coherent using that phase. The phase measurement and the phase correction process are not exact and that will yield phase noise. What is the phase noise of the DWD manetrons? Good magnetrons are 1 degree or perhaps less. How does that phase noise affect the dual-pol measurements theoretically (phidp, rhohv, Zdr)? The power measurement (dBZ) is not affected.
I believe the primary advantage the authors are showing is that the SNR of the SSPA (after pulse compression) yields improved SNRs. For high SNR areas of the precipitation, this advantage will not be manifest. In low SNR regions of the storm, the SSPA will show measurements that are spatially smoother.
All ppi images should be made much larger so that the phenomena the authors are describing can be clearly seen!!
If this paper is written up well, it would provide a great service to the community.
Other comments are embedded in the attached PDF document.