Meteor Scatter — VHF Propagation via Meteor Trails
Meteor scatter (MS) is a propagation mode that uses the brief ionised trails left by meteors burning up in the upper atmosphere as temporary reflectors for VHF signals. Each day, millions of meteors — most no larger than a grain of sand — enter Earth's atmosphere and vaporise at 80–120 km altitude, leaving ionised plasma trails that can reflect 2m signals for fractions of a second to several seconds. Specialised digital modes like MSK144 can decode these brief reflections and complete contacts over distances of 500–2,200 km that would be impossible without the meteor trail intermediary.
Ionised meteor trails
When a meteor enters the atmosphere, it collides with air molecules and vaporises in a process that ionises the surrounding gas. The resulting plasma trail has electron density high enough to reflect VHF signals at 144 MHz. The duration of this reflection depends on the meteor's size, speed, and the altitude of ablation. Most meteors leave trails lasting only 0.1–0.5 seconds — far too short for a voice contact but long enough for high-speed digital modes to exchange a complete contact in a burst. Larger meteors (still tiny — a few millimetres) leave longer-duration trails that can support multiple seconds of reflection.
MSK144 — the modern MS mode
MSK144 (Minimum Shift Keying, 144 WPM equivalent) was developed specifically for meteor scatter and is included in WSJT-X. It uses 72-bit messages transmitted in 0.072-second bursts — fast enough to fit a complete contact exchange within a single meteor trail reflection. The mode uses sophisticated forward error correction to decode even partial or distorted reflections. A complete MSK144 contact requires exchanging callsigns and a signal report in standardised WSJT-X format, with each station transmitting in alternating 15-second or 30-second periods depending on the configuration used. The software handles timing, encoding, and decoding automatically.
Major annual meteor showers
Annual meteor showers occur when Earth passes through debris trails left by comets. The Perseids (peak around August 12) and Geminids (peak around December 14) are the most productive for amateur radio meteor scatter, producing sustained rates of 50–100+ meteors per hour at peak. During shower peaks, MS contacts are made much more frequently because the increased meteor rate provides more reflection opportunities per hour. Sporadic background meteors occur continuously at lower rates throughout the year — experienced MS operators make contacts on random meteors on any day, not just during showers.
Planning and scheduling
Meteor scatter contacts are typically pre-arranged — operators coordinate a specific frequency, time, and sequence (who transmits first) by email, the ON4KST chat system, or social media before getting on the air. This is practical because MS is a point-to-point mode where you need to know where to point your antenna and when the other station will be transmitting. The ON4KST VHF/UHF chat room (on4kst.com) is the standard MS scheduling platform in Europe and increasingly in North America. Random calling on the MS calling frequency (144.360 MHz in North America) is also done, particularly during meteor shower peaks.
Equipment requirements
A 2m transceiver with at least 100W output, a directional antenna (Yagi with at least 7–10 elements recommended), and a computer running WSJT-X are the minimum requirements. Low-noise receive capability matters — a good preamplifier close to the antenna helps on weak meteor trails. The antenna needs to be steerable towards your target station — MS requires pointing at the specific great-circle path to the other station.
Configure WSJT-X for MSK144
Select MSK144 mode in WSJT-X. Configure your callsign, grid square, and audio interface. MSK144 uses the same sound card interface setup as FT8 — if you have already configured WSJT-X for FT8, changing to MSK144 requires only switching the mode. Set your radio to the calling frequency (144.360 MHz in North America) and select your transmit period (even or odd minutes).
Make your first contact
During the Perseid or Geminid peak, monitor 144.360 MHz on MSK144 and watch the decode window. You will see bursts of decoded callsigns appearing as meteor trails reflect signals from distant stations. When you decode a CQ from a distant station, double-click their callsign in WSJT-X to respond automatically. The software handles the MSK144 exchange sequence.
| Shower | Peak Date | Rate (ZHR) | MS Quality |
|---|---|---|---|
| Quadrantids | January 3–4 | 80–120/hr | Excellent but brief peak |
| Eta Aquariids | May 6 | 40–85/hr | Good — high-speed meteors |
| Perseids | August 11–13 | 80–150/hr | Best overall — warm weather, high rate |
| Orionids | October 21 | 20–40/hr | Moderate |
| Leonids | November 17 | 15–30/hr (variable) | Occasionally exceptional at storm years |
| Geminids | December 13–14 | 100–150/hr | Highest rate shower — excellent MS |
Can I do meteor scatter without a big antenna?
A modest Yagi of 7–10 elements will work MS contacts during good shower conditions, particularly on MSK144 which can decode very weak and brief reflections. A larger array (16+ elements, or stacked arrays) helps on random meteors and extends the range of contacts, but is not required for your first MS contact during a shower peak. Power matters too — 100W is the practical minimum, with 200–400W being more typical for serious MS operators.
What is the maximum distance for meteor scatter?
Single-hop meteor scatter on 144 MHz is limited by geometry to approximately 2,200 km — the maximum distance for a reflection off a meteor trail at the optimum altitude. Most MS contacts are in the 500–1,800 km range. Contacts shorter than about 300 km are geometrically difficult because both stations would need to be pointing in very different directions to reflect off the same trail point. The sweet spot for MS contacts is 700–1,500 km.
Does meteor scatter work on other bands?
Meteor scatter works best at 144 MHz (2m). It also works at 50 MHz (6m) where stronger reflections allow longer trail durations and sometimes even SSB contacts. At 432 MHz (70cm), MS is possible but trail durations are much shorter and contacts are much harder. Most MS activity worldwide is on 144 MHz. 6m MS is most active during summer Es season when both modes combine for productive operating.