the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 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.
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Status: final response (author comments only)
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RC1: 'Comment on egusphere-2026-198', John Hubbert, 06 Apr 2026
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AC2: 'Reply on RC1', Cornelius Hald, 29 May 2026
Thank you for your in-depth review of our manuscript. Your comments helped us a lot to become more precise in our wording and to make sure that the confusion that we had in our use of the terms you noted has been hopefully cleared.
We have tried to make more sense of the concept of SNR in the compressed long pulse and found that it is not as clearly defined as in a radar witout pulse compression. Noise measurements vary greatly between modulated and unmodulated pulses, and the compression gain has to be determined and added, while the tapering of the mismatched prototype of the transmitted pulse that is used for receiving leads to losses in SNR.
In terms of determining the effect of phase noise on our dual-pol measurements we would be interested in more detailed input from you. According to measurements done during the installation of our system, the phase noise is well below one degree, but we will try to repeat the measurement.
Please find attached the document with your detailed comments; we have added our responses into your comments, separated by a line of hyphens. Additionally, we provide a track-changes document where all changes that we made are easily visible. This will be under your comment "RC3", since only one attached document is allowed.
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AC2: 'Reply on RC1', Cornelius Hald, 29 May 2026
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RC2: 'Comment on egusphere-2026-198', Anonymous Referee #2, 07 Apr 2026
The paper is well written, however as submitted there are areas that require additional clarification.
In particular, the treatment of RhoHV should be improved to clarify how the values shown are achieved, especially in relation to SNR. Additionally, the role of noise and its variation in calculation of SNR should also be examined.
In the longer-range case where pulse compression is used, the authors do a good job of demonstrating the increase in sensitivity compared to a magnetron transmitter, and the benefits to data availability that this leads to.
See attached PDF for detailed comments.
With corrections the paper details a valuable study which will be of great benefit to those considering this new transmitter technology.
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AC3: 'Reply on RC2', Cornelius Hald, 29 May 2026
Thank you very much for your comments on our manuscript. They helped us a lot in improving several parts, especially - as you noted - those about noise and RhoHV. We are confident that the updated version is much more defined.
Please find attached the document with your comments - we added our answers in the comments after a line of hyphens. Additionally, we provide a track-changes document with all the changes that we made. It can be found in the reply to comment "RC3".
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AC3: 'Reply on RC2', Cornelius Hald, 29 May 2026
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RC3: 'Comment on egusphere-2026-198', John Hubbert, 07 Apr 2026
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2026/egusphere-2026-198/egusphere-2026-198-RC3-supplement.pdf
- AC4: 'Reply on RC3', Cornelius Hald, 29 May 2026
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CC1: 'Comment on egusphere-2026-198', Pekka Rossi, 20 Apr 2026
Thank you very much for this work. It is well written and will be an important contribution.
The use of a shared hardware architecture is justified for an objective comparison of transmitter data quality. However, an important system-level aspect that is not acknowledged is that SSPA enables alternative radar architectures, in particular antenna-mounted and independent horizontal and vertical transmitter designs. These system level architectures can substantially bring both performance- and maintenance-related benefits (e.g., by reducing waveguide losses, eliminating rotary joints, graceful transmitter degradation, combined simultaneous and alternating polarization data, new range/velocity mitigation techniques, all with overall simplified system complexity). Several commercially available SSPA weather radar systems already make use of such design at a similar cost to the magnetron system.
While these aspects may be out of the scope of the comparative study presented in this manuscript, an acknowledgment would help to put the results into a broader context that SSPA is more than a drop-in replacement for conventional cabinet-mounted architecture typically used in magnetron-based system but has promise to be an enhancement in the future.
Citation: https://doi.org/10.5194/egusphere-2026-198-CC1 -
AC1: 'Reply on CC1', Cornelius Hald, 29 May 2026
Thank you for your comment on the possibly different architecture of SSPA transmitter based weather radars. As you noted, the presented system is a modification of an existing magnetron radar. This means that that we could not profit from, for example, shorter waveguides, but on the other hand this design makes the two transmitter types much more comparable.
The first step in our evaluation was to see if the SSPA can provide a data quality comparable to a magnetron radar. This was, in our eyes, successful. Our next step will be to adapt scanning and signal processing to the unique properties of the SSPA and profit from it.
We have added a sentence to our discussion, where we mention that SSPA based radars can be built with the transmitter on the antenna and that this will provide further benefits.
Citation: https://doi.org/10.5194/egusphere-2026-198-AC1
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AC1: 'Reply on CC1', Cornelius Hald, 29 May 2026
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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.