Une belle ligne en effet, mais peut mieux faire … 
Oui on peut toujours mieux faire 
mais vu la rotondité de la terre tout çà reste à prouver
While on the subject of line of sight, I was glancing through an old microwave project book the other evening, it was either that or watching Vera, and came across a chapter discussing a solid-state laser transceiver. It got me thinking, this might make a very interesting summit to summit project, the question is, would a qso at 500THz count as a valid contact?
73
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Yes
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What band would that be recorded in for the database ?
Andy
MM7MOX
Once while on a call with an indian call centre (for HP hardware) the chap asked me to take a picture of a flashing light and send the image over via email…it took a while to explain why that was not easy. Instead, I did a video, uploaded to youtube and sent him a link…..
2m times 3 million 
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“Microwave”
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Already been done “sort of” around 2005 . Mirror signalling between GW/NW-072 Mynydd Enlli and the mainland. That would be about 1000TerraHertz (I think). Roger MW0IDX was one part of the team, but I’m not sure it was claimed in the database as a qso.
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En Europe, d’après le programme, il n’existe pas de ligne plus longue.
It’s the whole point of the calculation, it does take into account the curvature.
Take a point in the middle of the sea, at human height, and you will find 5 km ligne of sight only. Which is correct.
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my old boss hated jira and therefore all his tickets were a one liner title with no detail.
sometimes it’s the people not the tools that are the real problem
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Of course the smart money will be on non-LOS optical links using cloud scatter. Just saying…
I would say it would not count. Such a contact would not comply with general rule 3.7.1 criterion 2:
“All operation must comply with the amateur radio licensing regulations and must use the
permitted amateur radio bands of the country in which the Association is based.”
A contact using 500THz complies trivially with the first part because the licencing regulations do not apply, but does not comply with the second part. It does not say that the frequency in use must be permitted. It says that the frequency in use must be in a permitted amateur band, which 500THz is not.
Martyn M1MAJ
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Is a NoV possible for 500 THz? A cursory glance at the band plan says:
Access to frequencies >275 GHz by Full Licensees is also possible by NoV
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It’s interesting how perception and memories change.
When I was first licenced (some years back), UK hams had unfettered access to all freqs above 275GHz. Ha! We all thought unlimited access but this is really university or military stuff. Now in 2026 I have 2x 122GHz transceivers and some ham friends are looking into 241GHz gear which is really close to the magic 275GHz.
What passed me by was the introduction of needing a NoV for access to above 275GHz and there is now a list of banned frequencies and limits on location. Looks like that NoV was introduced in 2016. But the NoV stops at 3000GHz. Above that it is back to the free-for-all of old.
No NoV needed for ops using LEDS or LASERS. Just remember, do not look into the beam with your remaining good eye 
However, the permitted amateur band requirement probably exists to stop cross-band operation between 11m CB and ham bands. Or the use of cross band ops between ham bands and UHF FRS, PMR446 radios. Why? I can’t remember off the top of my head but there was felt to be a need when it was drawn up.
Maybe the rules need clarifying which is a lot of effort for what probably nobody will ever try. But there is an upcoming rule change/clarification about multiple licence usage so it could be added in then. In the meantime a statement from the MT saying optical comms are OK should probably do.
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They don’t need to be that close: the path from W7U/SU-012 to W0C/RG-001 was covered by heliograph on September 17, 1894. That’s almost 300km.
Probably didn’t get logged in the SOTA database, however.
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I do the same at home
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If we can’t do SOTA then theres always Shakespeare.
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