What changed
Weak signal, scatter and moonbounce — edited Aug 31, 2026 by Unknown editor
This is the first recorded version, so every line is shown as added. Note: Imported from content/wiki
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VHF and UHF are usually described as line-of-sight. They are not, and the techniques below are
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where the most technically demanding operating in the hobby happens.
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## Meteor scatter
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Millions of meteors enter the atmosphere daily, each leaving a briefly ionized trail that reflects
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VHF signals for a fraction of a second to a few seconds. Contacts of 500–1,300 miles on 6 m and 2 m
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are routine.
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- **Mode:** MSK144 in WSJT-X, which packs an exchange into 72 ms bursts.
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- **When:** early morning any day; far better during showers — Perseids in August, Geminids in
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December, Quadrantids in January.
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- **Station:** 100 W and a single yagi is enough on 6 m.
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## EME — moonbounce
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Aim at the Moon, and roughly 2.5 seconds later your own signal comes back 250 dB weaker. It is the
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ultimate DX path: anyone who can see the Moon at the same time as you is workable.
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- **Mode:** Q65 and JT65 make it achievable with a single yagi and 100–500 W on 2 m or 70 cm, which
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was impossible before weak-signal software.
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- Watch for Doppler shift, spatial polarization offset, and the extra path loss when the Moon is at
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apogee.
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## Tropospheric propagation
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Temperature inversions — common over water, and after calm high-pressure evenings — form ducts that
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carry 2 m and 70 cm signals hundreds of miles. Check a tropo forecast map, then listen on the
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calling frequencies (144.200 and 432.100 MHz USB) rather than FM.
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## Sporadic E
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Intense patches of ionization in the E layer light up 6 m — the "magic band" — for minutes to hours,
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mostly in late spring and early summer, giving 500–1,400 mile openings and occasionally 2 m.
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## QRSS
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Extremely slow Morse, with dot lengths of 3 to 120 seconds, decoded visually on a spectrogram
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rather than by ear. Milliwatt beacons on 30 m are received across oceans. It teaches more about
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signal-to-noise and bandwidth than any book.
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## What these have in common
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Narrow bandwidth, patience, accurate time and frequency, and good antennas —
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see [antenna theory](/wiki/technical/antenna-theory) and
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[propagation](/wiki/technical/propagation).