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.

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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.”

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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 ...by 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"

PI9CAM bounces Slow Scan TV signals off the moon at 1296 MHz - 30th Dec 2022

On the 30th of December 2022, the Dutch amateur radio station PI9CAM carried out a series of tests by bouncing Slow Scan TV (SSTV) signals off the moon at 1296 MHz. PI9CAM is the callsign of the special station at the Dwingeloo Radio Observatory in the north-east of the Netherands.

PI9CAM used the 25-metre dish at the site which was originally built in 1956 and was once the largest radio telescope in the world. As far as I know, they were using 100-watts for the SSTV tests.

One of those monitoring these tests was Rob, M0DTS in the NE of England. Listening on a frequency of 1296.120 MHz USB, Ron managed to get these images.

While the images have a lot of noise in them, it should be remembered that these 23cms SSTV signals on 23cms were bounced off the moon.

SSTV is an old analogue technology where signals well above the noise floor are usually required for a good decode and picture. It's not some sort of modern digital technology which decodes signals buried in the noise. 

This short video clip shows what the slow scan tv signal from the moon sounded like...

pic.twitter.com/rj829Q6zdb

— Rob Swinbank (@M0DTS) December 30, 2022

For reception of the 23cms signal, M0DTS was using a 3-metre dish with a dual polarity feed and a 0.2dB noise figure low-noise amplifier.

Thanks to Rob, M0DTS for the above information.

For more posts on the blog about the microwave bands, see my Microwave page.

Guest Post: VHF & UHF operation... by Alan Johnson, VK3DXE

VK3DXE in Australia recently posted this article on his Facebook page and it is republished here with his kind permission to reach a wider audience. In it, he outlines what attracted him to the VHF bands.

I've been a member of a number of VHF/UHF Ham pages for a while, and keep seeing a lot of misconceptions and myths being picked up and quoted over and over by newcomers, and sadly a lot of not-so-newcomers who’ve brought their HF Game with them to the higher bands. 

I first became fascinated with VHF tropo propagation as a young kid living in the country, where we only had 2 TV channels, but occasionally we’d get the channels from the city suddenly appear when the conditions were right. You can imagine the excitement for a young kid way back then who's suddenly discovered some new TV channels! We had a neighbour up the hill who happened to be a Ham, and he explained to me how tropo worked. I was hooked, and from then on, whenever the weather forecast maps looked promising, and we got the right conditions, summer or winter, I’d start looking for the telltales that the city channels were going to pick up.

Fast forward 7 or 8 years, and I eventually got my Australian Novice license, quickly upgrading to the Advanced Call within a year when I was about 15 or 16. We were near the top of the sunspot cycle at the time, so I went nuts on HF for the next few years. But as the sunspots waned, I was drawn to the higher bands…..

As a youngster it was sometimes tough putting up a decent 2m yagi, but I always found a way of getting something in the air, and making the most of what I had available, even when living in rental housing. I just had to be creative, and sometimes a bit cheeky. The good thing about a 2m yagi though, was that even if anybody noticed it, they'd just figure it was a TV antenna.....  

You can build a small yagi like this in an afternoon with some simple tools.

I learned about aircraft enhancement in the days before we had all the funky tools we have today, before the widespread coming of the Internet. We managed to regularly make 2m SSB contacts of up to 700km (400+ miles) with smallish yagis and relatively low power - one path of 740km was quite good even with my portable station, with just a little 4 element yagi and Yaesu FT-290R II running only 2.5 watts!  

Living in inner city urban areas, I really began to appreciate low noise antenna designs (DL6WU & K1FO were the early leaders) and radio frontends that didn't collapse in the presence of strong out of band signals. I learned about GaAsFET LNAs (Low Noise Amplifiers, or preamps) too, and the importance of what was in front of the radio on RX. You have to think of your station as a system.

In the early 1990’s the Bible of VHF+ was published. The VHF/UHF DX Book very quickly became the must-have tome in every serious VHFer’s library. Although some of the chapters are now a bit dated, especially those relating to equipment, I strongly suggest everybody with even a fleeting interest in the higher bands downloads a copy and reads it. Hopefully it’ll help to undo some of the myths about VHF+ that have persisted in the hobby for far too long, things like the belief that troppo is only a summertime thing, and that troppo is the only worthwhile propagation mode on VHF+. Download it here: http://www.trpub.net/assets/applets/VHF-UHF_DX_Book.pdf

As the Internet came along and people developed all sorts of new tools, and we learnt about Forums, email reflectors, and then FaceBook pages, the opportunities to learn and collaborate grew amazingly.

Then the WSJT suite of software changed things overnight. All of a sudden, the little guys running just 100w to a 10 element yagi could successfully work stations on the other side of the world on 2m and above via EME, or Earth-Moon-Earth. I worked a dozen countries with just a single yagi and less than 200w at the antenna. 

Just last weekend, I was listening to HB9Q in Switzerland on 23cm for hours here in my /P shack while we're living in temporary accommodation, with a beautiful steady signal, often quite audible in the speaker, all on a tiny 60cm x 90cm gridpack antenna. 

Eventually, once I get my 2.4m dish in the air and find a suitable amplifier, I hope to be able to work him on 23cm SSB at home.... JT65 and Q65 will be an absolute walk in the park.

Lots of signals on 23cm with the gridpack.

In Australia, where we don’t have the population of Europe or North America, the Ham fraternity have embraced WSPR on 2m, and have demonstrated VHF paths of sometimes thousands of kilometres that no amount of listening to white noise for beacons or a coincidentally-timed CQ would find with the naked ear. Those paths are now being exploited regularly on digital modes, with people moving to SSB when conditions become strong enough. I've been around the hobby for a long time, but so too have the "old farts", some of whom vociferously decry the use of digital modes, but our experience here in Australia has really demonstrated how digital modes can be exploited to help get those SSB contacts that very probably would never have taken place otherwise. WSPR has been so successful that there are now WSPR beacons on Hawaii (often heard on West Coast USA), and in New Zealand, with a fantastic signal into East Coast Australia during the summer tropo season.

A little 4 element Cushcraft yagi. Even this is enough to decode some of the Big Guns off the Moon. I had many WSPR 2-ways with this one, out to 700km with Aircraft Enhancement

Next time you're asked by anybody (PARTICULARLY CHILDREN AND YOUNG PEOPLE) about the hobby, instead of trying to excite them with boring stories of talking on HF or FM repeaters, which they tend to equate with the equivalent of dialing random numbers on their cellphone to talk to old farts with bad combover hairstyles about their hemorrhoids, try telling them about stuff like all the space comms stuff we have access to, and can actively participate in, like using the repeater on the ISS, and all the other satellites we have access to. Tell them about Moonbounce, and how you can actually demonstrate the speed of light in action - you know exactly when the station on the other end has stopped transmitting, but can still see and hear his signal coming back at you for those additional 2 or 3 seconds it takes to travel all the way to the Moon and back. THAT gets young people more excited than listening to old farts! Try talking to them about meteor scatter, and how the military has used it for communication systems to counter the effects of comms satellites being wiped out in a conflict, or a dirty big EMP bomb wiping out HF. Tell them about aircraft enhancement, which is really bistatic radar, and how some clever dude worked out a way of using it to detect stealth aircraft by using commercial broadcasters behind enemy lines to illuminate the target. Tell them about all the really funky atmospheric and weather science they can learn just by playing with weak signals on VHF+. Tell them about the funky networking knowledge they can gain from modes like D-Star, IRLP, Echolink, etc. 

The /P shack while I'm away from home

Anyways, I've written this piece in response to a recent influx of newcomers and not-so-newcomers to the higher bands, possibly on the back of purchasing themselves a brand new IC-9700. I fully appreciate that everybody starts their learning journey from different places and has different interests, but some of the myths and misunderstandings I see are staggering. Unfortunately, so much of the Ham narrative has become very HF-centric, and that mindset often pervades discussions, and the marketing of the hobby, so this is just my little bit to try to counter some of that.  Remember to download the VHF/UHF DX Book from the link above, and jump onto some of the more technical pages and start learning. 

I'll be doing a bit of a write up soon on the importance of frequency accuracy and STABILITY on VHF+. Watch this space.

Enjoy!

de VK3DXE

EA8CXN completes 1296 MHz contact by bouncing a signal off a cruise ship - Apr 2021

I recently read an interesting post on the website of César, EA8CXN about a 'Ship Scatter' contact on 1296 MHz (23cms)!

The map above shows the scenario. EA8CXN and EA8CSB are on the island of Tenerife in the Canary Islands and they cannot complete a contact directly on 1296 MHz due to local mountains.

They did however manage to complete a contact by bouncing the 23cm microwave signals off a passing cruise ship which is about 60kms away! Amazing.

After initially completing a contact on FT8, they managed to complete a QSO on SSB.

EA8CXN was running 100 watts in a 1-metre dish with horizontal polarization. EA8CSB was using just 2.5 watts into a vertical Diamond X-7000.

Check out the post on EA8CXN's website for more info and to see the SSB contacts.

New 2700km+ IARU Region-1 tropo record on 23cms between Ireland and the Canary Islands - 17th July 2020

On the 17th of July 2020, there was an opening between the Canary Islands and the UK & Ireland on the VHF & UHF bands. A remarkable contact was made on 1296 MHz between EA8CXN and EI2FG which turned out to be a new IARU Region-1 tropo record for the 23cms microwave band.

In a report on his website, Cesar EA8CXN reports that there was a good tropo opening on July 17, 2020,  between Ireland-England and the Canary Islands.

In the evening, EA8CXN completed contacts with G7RAU, G4LOH and EI20C (op. Mark, EI3KD) on 432 MHz. EI20C mentions that John, EI2FG is also active on 1296 MHz so tests begin.

G7RAU is the first to complete a successful contact on SSB on 1296.200 MHz using just 5 watts into a 56 element Yagi. G4LOH also completed a contact.

After a period of deep QSB, a successful SSB contact was completed with EI2FG on 23 cms with 5/1 and 5/4 reports exchanged. The distance was an amazing 2714 kms.

Not only was this the first ever contact between Ireland and Canary Islands on 1296 MHz but it was also a new IARU Region-1 tropo record for 23 cms.

The map above shows the limit of the new record. The old record of 2661 kms was set on the 14th of July 2017 between EA8AVI and M0VRL.

The map also suggests that there is plenty of scope for the record to be broken with sea paths further north to the west of Wales and up the Irish Sea.

Equipment... For the record SSB contact on 23 cms, EA8CXN was using 150 watts into a small parabolic dish which was 50 cms in diameter. The feed point for the dish was a 3-element horizontally polarized PCB Yagi.

EI2FG was using his EME station of 200 watts into a 3-metre parabolic dish. The feed point was Right-Hand Circular Polarization on transmit and Left-Hand CP on receive.

Propagation... The mode of propagation was via a maritime duct over the ocean.

This duct exists for long periods of the year between the Canary Islands and the western coast of Spain & Portugal and then gets extended sometimes further north to the UK and Ireland.

In conclusion.... To put this this record 2714 km contact on 1296 MHz, a microwave band into perspective, it's worth remembering that the distance across the North Atlantic from Ireland to Newfoundland is around 3000kms. 

It's also likely that the record distance could be exceeded further north to Wales or up the Irish Sea as outlined earlier. The biggest obstacle at the moment is probably the lack of stations on 23 cms.

If the D4VHF station on Cape Verde Islands off the coast of Africa ever became operational on 1296 MHz, the record could well be extended to about 4000 kms.

Links...

1) EA8CXN post in Spanish

Local experiments on 23cms...

Every Tuesday evening, we have a local VHF net in Cork and a few of us get together for a chat. We use the the 6m, 4m, 2m and 70cms bands and which one we use depends on which Tuesday of the month it is.

It usually covers the first four Tuesdays of the month and if there happens to be a fifth Tuesday then we gave it a skip. A few weeks back, we thought it might be a good idea to use the fifth Tuesday in a month for experimentation, to try something that we don't usually do.

From this concept came the idea to try the 23cms band, i.e. 1296 MHz.

Denis, EI4KH near Watergrasshill has a Yaesu FT-2312 23cms transceiver running 4 watts on FM only and his antenna is a 26 element Yagi horizontally polarised.

A sked was organised with Don, EI8DJ who was located in a car at Camden near Crosshaven at the mouth of Cork harbour, a distance of 22 kms or 13.8 miles.

While the path wasn't line of sight, both Denis and Don were in good high locations. EI4KH was about 120m above sea level while EI8DJ was at a spot about 45m above sea level.

As the plot shows below, any obstructions on the path were several kms distant which made them less of an obstruction.

For EI8DJ's portable set-up, he was using a scanner for receive with a home made Bi-Square antenna shown below which was sitting on the dash of his car.

Using a frequency of 1290.000 MHz, EI8DJ managed to hear the FM signal from EI4KH at an estimated S'4' signal strength and a successful 23cms to 2m crossband contact was completed.

EI8DJ found the Bi-Square to be suprisingly directive and later peaked the FM signal from EI4KH to a maximum of an estimated S'7' signal strength.

The experiment was repeated with EI8DJ back in his driveway which is some bit lower than his portable location. From his home location, EI8DJ couldn't hear any sign of the FM signal from EI4KH.

While the distanced achieved were nothing special, it was interesting to see some local activity on the lowest of the amateur microwave bands.

Notes:
1) The beam heading for Denis was 170 deg.