Friday, December 8, 2023

Promising news for the amateur radio 23cms microwave allocation - Nov 2023

With the development of GPS and other radio navigation satellite systems, the part of the radio spectrum above 1 GHz has become very attractive and this has put pressure on the 23cms / 1.3 GHz amateur radio band. For the last few years, it looked as if the decades old allocation might be lost altogether.

The International Amateur Radio Union (IARU) are now reporting that an agreement has been reached for a recommendation for 23cm band amateur operations to be allowed on a non-interference basis alongside the co-frequency radio navigation satellite service (RNSS). The recommendation from the the ITU‑R Radio Assembly (RA) will form a component of the WRC-23 discussions which are ongoing until December 15th. (see update below)

While the threat to the 23cms band hasn't been removed completely, it is significant that a technical sub group has reached an agreement and hopefully it will be approved at the main conference.


Update - 8th Dec 2023: 23cm band outcome approved at the 7th Plenary meeting of WRC-23

The following was posted today on the IARU web site: During the WRC-23 deliberations, strong positions were expressed by all the parties involved. The result is a well-supported compromise for a footnote in the Radio Regulations regarding amateur and amateur satellite service operation in the 1240 – 1300 MHz range. The footnote reminds administrations and amateurs of the need to protect the primary RNSS from interference and provides guidance to administrations to allow both services to continue to operate in this portion of the spectrum. The compromise was formally adopted by the Conference Plenary on December 8 and is not subject to further consideration during the final week of the WRC. The IARU team continues its work on other WRC issues including the development of agendas for future conferences.

IARU President Tim Ellam, VE6SH, noted “This is a very good result for the amateur services. The decision reached at WRC-23 on this agenda item makes no change to the table of allocations nor incorporates by reference M.2164 into the Radio Regulations. The addition of a footnote that provides guidance to administrations in the event of interference to the RNSS is a good regulatory outcome for amateurs and the primary users of this band.”


The image above from the IARU gives a good overview of what is going to happen to the 23cms amateur radio band.

1) Parts of the band restricted to just milliwatts... The current band is 60 MHz wide going from 1240 MHz to 1300 MHz. There will be a severe power restriction for large segments of the band that might overlap the radio navigation satellite signals.

Example...The section of 1240 to 1255.76 MHz overlaps the Russian Glonass system, Here, just 1.26-milliwatts in a 150 kHz wide signal is allowed. Note that this is effective radiated power so it includes any antenna gain. In simple terms, this prevents any amateur use of these segments of the band.

2) Protecting the DATV segment... The key target for the IARU has been to protect the main centres of activity and one of these is the Digital Amateur TV segment around 1260 MHz. The frequencies below are from the current IARU Region 1 band plan...

1243,250 - 1260,000 * (D)ATV 1258.150 - 1259.350 Repeater output

There will be power restrictions in terms of EIRP (combined power and antenna gain) and the IARU gave these examples...

1255.76 to 1256.52 MHz (760 kHz) = 250W eirp... 4W into typical beam antenna (18dBi) or 60W into 6dBi mobile ant.

1256.52 to 1258 MHz (1.48 MHz) = 125W eirp...2W into typical beam antenna (18dBi) or 30W into 6dBi mobile ant.

3) Protecting the narrowband segment... The other important part of the band from an amateur radio point of view is the segment for narrowband modes from 1296 to 1300 MHz (e.g. CW, SSB, FM, FT8). Here, the plan is for a simpler power output restriction rather than taking the antenna gain into account as well.

1296 – 1298 MHz = 50W pep into antenna & 1298 – 1300 MHz = 150W pep into antenna

There is a higher power limit for moon bounce operation as long as the antenna has more than 30dBi gain and is pointing more than 15 degrees above the horizon.

4) Amateur Radio Satellites... There is a complex set of power restrictions covering narrowband operation in the amateur satellite band from 1260 – 1262 MHz. These range from very low power at low elevation angles to higher power levels at high angles (−3 dBW for 0° to 15° / 17 dBW for 15° to 55° / 26.8 dBW for 55° to 90°).

I'm not aware of any amateur satellites using these frequencies or if any licensing authority will be keen in the future to give permission to any potential new satellites considering the contested nature of the band.

23cms / 1296 MHz... Why does it matter??? AMSAT UK sums it up nicely... "The 1240 – 1300 MHz band is important for the amateur radio service, being the lowest allocation for radio amateurs on which typical microwave propagation can be experienced. Access to these frequencies is facilitated by commercially available equipment and provides a ‘bridge’ building motivation to become involved in more specialized higher frequency microwave and millimeter wave operations providing the self-training which is at the heart of amateur radio."

In conclusion... As the IARU notes..."The final recommendation represents the culmination of more than 4 years of work by the IARU team within the ITU‑R study groups to ensure the best outcome for amateur radio in the face of intense regulatory, political and commercial pressure."

Some people may be disappointed with some of the proposed changes but there really isn't another alternative. The choice here is pretty simple... either the amateur radio service can co-exist with radio navigation satellite systems in the 23cms band on a non-interference basis or have no amateur allocation there at all.

If the plan is agreed at the conference as expected then it offers some certainty to radio amateurs who want to use the band, They can buy or make equipment safe in the knowledge that the band won't be gone in a few years time.

It also allows the radio amateur service some protection in that we can hide under the protection of these radio navigation satellites. It's highly likely that the various governments would have serious objections to any commercial interests trying to get access to the 23cms band in the future.

Further reading... You can find more information at the links below...

1) Potential Interference To Galileo From 23cm Band Operations Peter Blair, G3LTF (2005) 

2) 23cm band in the spotlight with regulators... AMSAT-UK (Feb 2021)

3) 23cm Band and RNSS Coexistence September Update... AMSAT-UK (Feb 2021) 

4) Austria restricts 23cm band operation... AMSAT-UK (March 2023)

5) ITU‑R Recommendation M.2164 on 23cm amateur service and RNSS operations now published in time for WRC-23 discussions ...IARU (Nov 23, 2023)

6) ITU-R M.2164 Summary ...IARU (Nov 23, 2023) 

7) Recommendation ITU-R M.2164-0 : Guidance on technical and operational measures for the use of the frequency band 1240-1300 MHz by the amateur and amateur-satellite service in order to protect the radionavigation-satellite service (space-to-Earth) ...ITU (Nov 23, 2023) 

8) IARU Region 1 band plan for 23cms ...IARU (March 2021)

Addendum...After I put up this post, the RSGB released this related video which was made in October 2023 (1h 42m in length)...

1. Barry Lewis, G4SJH talks about "Amateur/RNSS coexistence in the 23cm band"
2. John Worsnop, G4BAO considers "How will the possible RNSS changes affect narrow band DX operation and EME?"
3. Dave Crump, G8GKQ looks at "The future of ATV in 23cms"


Anonymous said...

Thanks John. Nice piece of work explaining it and bringing us up to date. Karl Ei5DPB

Anonymous said...

Thank you for the new information. I hope this can find a positive response.