getontheairMoonbounce (EME)
Earth-Moon-Earth (EME) contacts bounce your signal off the Moon and back to another station that can see the Moon at the same time. The echo arrives about two and a half seconds after you transmit, weakened by the round trip of roughly half a million miles. It's the longest path most hams will ever work, and Technicians have full privileges on every EME band from 6 meters up.
Modern digital modes changed EME. What once took huge arrays and a kilowatt can now be done, against the big stations, with one long yagi and a few hundred watts on 2 meters. This page gives an honest picture of what that takes and how to start.
Independent guide, not affiliated with ARRL, the WSJT Development Team or any EME group. Sub-bands below are from the ARRL band plan and WSJT-X's default frequency list.
EME v1.0 · written 2026-10-08 · band plan, WSJT-X version and contest dates checked as of Oct 2026
What makes EME hard
- Path loss. The Moon is far away and a poor reflector. Signals come back far below the noise, which is why digital modes that decode below the noise floor dominate.
- Doppler. Earth's rotation and the Moon's motion shift the echo's frequency, by hundreds of hertz on 2 m and by kilohertz to tens of kilohertz on the microwave bands. WSJT-X can track and correct it automatically with a CAT-controlled radio.
- Libration fading. The Moon's surface is rough and slowly rocking, so echoes flutter.
- Faraday rotation (mainly 2 m and 70 cm). The ionosphere rotates the polarization of the signal. Some nights a horizontally polarized yagi hears nothing for a while, then everything. Cross-polarized arrays and the MAP65 software deal with it.
- Timing. Both stations need the Moon above their horizon at the same time. Many small stations work best at moonrise and moonset, when reflection off the ground in front of a low antenna can add several dB.
Bands and sub-bands (US)
| Band | EME segment (ARRL band plan) | WSJT-X default dial | Typical digital mode |
|---|---|---|---|
| 6 m | No separate EME segment; weak-signal area near the bottom of the band | 50.211 MHz (Q65, EME) | Q65-60A |
| 2 m | 144.00–144.05 MHz CW EME; 144.10–144.20 MHz EME and weak-signal SSB | 144.116 MHz (Q65, EME); 144.120 MHz (JT65) | Q65-60A, JT65B |
| 1.25 m | 222.000–222.025 MHz | 222.065 MHz (Q65 and JT65) | Q65 |
| 70 cm | 432.00–432.07 MHz | 432.065 MHz (Q65, EME; also JT65) | Q65-60B |
| 23 cm | 1295.800–1296.080 MHz | 1296.065 MHz (Q65 and JT65) | Q65-60C |
| 13 cm | 2304.000–2304.100 MHz | 2304.065 MHz | Q65-60C |
| 5 cm | 5760.0–5760.1 MHz | (set your own) | Q65-60D |
| 3 cm | Weak-signal segment 10367.000–10368.300 MHz | (set your own) | Q65-60D or E |
The mode suggestions are from the WSJT-X User Guide's "Tips for EME" section. It recommends a suitable Q65 submode for EME on any VHF or higher band, which has replaced most older JT65 and QRA64 use. JT65 is still heard, especially on 2 m.
9 cm (3.4 GHz): the ARRL band plan still lists an EME calling frequency at 3400.1 MHz, but the band is no longer in §97.301. ARRL's 3 GHz band page says secondary amateur use of 3.3–3.45 GHz may continue for now under footnote US103 to the US Table of Frequency Allocations, until new flexible-use licenses are issued there, while 3.45–3.5 GHz closed in April 2022. Read that page for the current status before you plan anything on 9 cm.
Check one frequency against Part 97 and the band plan with the band-plan checker.
Station reality check
There is no single minimum station. What you can work depends on the other station as much as yours. Some honest rules of thumb:
| Station | What to expect |
|---|---|
| Receive only, single yagi on 2 m, good preamp | You can decode the biggest EME stations with Q65 or JT65 on many nights. This is the right first step. |
| One long 2 m yagi, a few hundred watts, preamp at the antenna | Contacts with large stations, especially at moonrise and moonset. The WSJT-X modes made this practical. |
| Array of several yagis with elevation control, high power | Contacts with mid-size stations too, not just the largest ones. |
| Dish antenna on 23 cm and up | Very active. Doppler and pointing accuracy become the main problems. |
What matters most, in order: a low-noise preamp at the antenna, low feedline loss, the antenna's gain, and only then power. Doubling power is 3 dB. A good preamp at the feedpoint can be worth more than that on receive.
Safety: high power into a high-gain antenna means real RF exposure close to it, especially on 70 cm and up and with dishes. Run the numbers on RF exposure and the RF exposure calculator before you transmit, and keep people out of the main beam.
Where to start
- Get the software. WSJT-X (version 3.0.2, June 18, 2026, as of Oct 2026) includes Q65, JT65, Doppler tracking and astronomical data for the Moon. MAP65 and QMAP, from the same team, add wideband reception of a whole EME sub-band.
- Listen during a contest weekend. EME activity peaks during the ARRL International EME Contest. 2026 dates: August 8–9 and September 5–6 for 2.3 GHz and up, and October 31–November 1 and November 28–29 for 50 to 1296 MHz (ARRL EME contest). The two remaining 2026 weekends are on the bands most beginners start with.
- Decode before you transmit. With a single yagi, aim at the Moon near moonrise or moonset and watch the Q65 sub-band. Seeing decodes from big stations proves your receive chain works.
- Check your own echoes (bigger stations). WSJT-X's Echo mode measures your own returns from the Moon.
- Make a sked or answer a big station's CQ. Big stations often call CQ and work everyone who can be decoded. Follow the WSJT-X User Guide's QSO procedure for Q65.
EME and POTA
EME contacts count as normal amateur contacts. A Q65 Moon contact logged as a data contact is a valid QSO. In practice, EME needs a large antenna, elevation and a quiet site, so it's rarely done from a park. EME expeditions to rare grids do happen, with a lot of planning and hauling.
Habits / gotchas / checklist
Sources (checked Oct 2026)
- WSJT Development Team, WSJT-X and its User Guide ("Tips for EME", Q65 and JT65 sections). Default dial frequencies are from WSJT-X's built-in frequency list.
- ARRL, band plan (EME segments for 2 m, 1.25 m, 70 cm, 23 cm, 13 cm, 5 cm and 3 cm).
- ARRL, International EME Contest (2026 dates).
- FCC §97.301 (amateur allocations).
Related
- Meteor scatter · Microwave · ATV and DATV
- Technician HF and VHF overview
- WSJT-X — setup, timing and logging
Notes & edits
Comments and proposed markdown sit in a queue. Nothing is public until it is reviewed. How this works.