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Horizon | Shack1 | Shack2 | Relay/LNA
LNA Ext | LNA Int | Amp 1 | Amp 2
BPF Plot | LNA Plot | BPF+LNA
VA3TO EME station details:
Transceiver: Yaesu FT-847 w/ split RX & TX ports on VHF.
Antennas: 2 x Homebrew K1FO-12 Yagis. Approx. 15dBd total gain.
Rotators: Azimuth = Hygain Ham-IV, Elevation = Kenpro KR-500.
Amplifier: Homebrew W6PO style 8877 (3CPX1500A7) 1500W Power Amplifier.
LNA: Homebrew ATF-54143 PHEMT on a PA3BIY PCB. Gain = ~21dB, NF = <0.25dB.
BPF: DCI 146-4H, 4MHz bandwidth @ 2 metres.
Feedline: 7/8" LDF-5 Hardline on TX and RX, 50 feet each from shack to Relay Box.
Power divider: Homebrew 2 port 1/4 wavelength.
Relay: Transco 11300.
Transition cables: FSJ4/50 "Superflex".
Current available ERP: 32 KW
Operator: Hugh Duff
Location: Waterdown, Ontario, Canada. 40 kM NW of Niagara Falls.
Grid: FN03bi
One of my long standing goals since becoming a Ham Radio operator was to try EME
(Earth-Moon-Earth) or "moonbounce" whereby suitably equipped stations
attempt to communicate with each other using the moon as a passive reflector.
With directional antennas pointed at the moon, a small portion of the transmitted
radio energy is reflected back to earth making 2-way communications possible.
Some consider this to be the ultimate challenge in the hobby since it requires
operator skill and great attention to detail in the assembly of the station equipment
to maximize gain and minimize losses in every component from the radio to the antenna array.
My goal was realized on August 29, 2005 when I made my very first EME contact
using WSJT JT65b digital mode. A handful of other digital mode contacts were
subsequently made but the real thrill occurred on October 23, 2005 during the fall
ARRL EME contest when I completed my first CW (Morse Code) EME contact, which is
considerably more difficult. The excitement was
heightened by the fact that I was operating QRP (low power) by EME standards,
using just 160 watts with my 15dBd antenna, and the contact occurred
randomly rather than by pre-arranged schedule. Furthermore, the moon was at a high
elevation so there was no ground gain advantage. Granted, EME superstation W5UN
was at the other end of this contact.
I live in a subdivision on a small lot
arial view of my neighbourhood here . It isn't feasible for me to put up a large antenna array so
I took on the challenge to see what I could do with just 2 yagi antennas. My low power
and small antenna setup is considered "QRP" or very modest relative to a typical EME station
with 4 or more yagi antennas. The increased challenge gives me a greater appreciation for each and every successful contact.
See my EME Initials LOG here;
VA3TO EME Contacts to date: 10 CW Initials, 114 WSJT (Digital Mode) Initials.
Sample WAV audio file;
Listen to a raw WAV file of IK3MAC replying to me in CW on Dec.10, 2005. This was my second CW contact with Graziano.
(Note: Some browsers may require you to right-click and select "Save Link Target As...")
I'm hooked on the challenge and thrill of EME communications. Family and work commitments limit my operating time but I always look forward to having the opportunity of pointing the antennas at the moon to make more contacts !
In the spring of 2009 I set up a 23cm EME station using a small dish. Details here 23cm microwave moonbouce station.
Thanks to following people for their patience, encouragement and help in making my EME effort a success:
Rick, VE3RNK and Jon, VA3RQ for helping me pour the concrete foundation for the tower, errect the tower and install the antenna array.
Paul, N1BUG for allowing me to draw from his wealth of knowledge and experience in EME stations and propagation, and amplifier construction tips.
Bob, ZL1RS for encouraging me to try EME with a small station when we met at the 2004 CSVHFS meet in Mississauga (Toronto), Canada.
Lionel, VE7BQH for sharing his expertise in antenna design & stacking information.
Dave, W5UN for giving me the thrill of working my first CW and WSJT contacts off the moon.
Some interesting EME related facts:
- The moon is nearly 400,000KM away from Earth. Since radio waves travel
at the speed of light (300,000KM/sec.) the round trip takes approximately 2.5
seconds, so it is possible to hear your own echoes.
- Most of the radio energy pointed at the moon disperses and continues off into space while
some of the signal gets absorbed by the surface. A mere maximum of 7% of the signal is reflected back to earth.
- There are no modes of enhancement for EME signals but there are some phenomenon that can be a detriment.
The key is to operate when the combination of these phenomenon is least prevalent.
The sun and other celestial bodies generate electrical noise which results in increased radio
noise levels, making it more difficult and sometimes impossible to hear typically weak EME signals.
Such an occasion would be around the days of a New Moon when the sun and moon appear close
to each other in the sky, or the coincidence of a noisy galaxy or other celestial body behind the moon.
The effect of such noise can be quantified and is expressed by a degradation factor in negative dB.
Also, the orbit of the moon is slightly elliptical so the degradation factor may increase
by as much as 2.3dB when the moon is furthest away from Earth (Perigee = nearest, Apogee = furthest).
Fortunately the incidence of high degradation from the above factors is predictable
using orbital data and is charted in a calendar allowing EME operators to choose optimal days to operate.
(See W5LUU's Moon Data Calendar in the links below).
- Weather does not impede the prospect of successful EME operation on VHF frequencies
so contacts can occur during heavy cloud and precipitation (barring any ill effects to the
antenna system from moisture).
- The phase of the moon (i.e. "half moon", "full moon") has no effect on moonbounce operation. The moon is present
in its entirety despite how much is illuminted by the sun. (No laughing, this question has been asked several times).
- Over-the-horizon EME, when the moon is just rising or setting allows terrestrial equipped stations with no antenna elevation
capability to participate in EME communications. The operating window
is limited but there is a possibility of up to 6dB in ground gain
enhancement whereby in-phase reflections off the Earth are added to the
line of site path, increasing the overall signal level.
- Successful EME contacts have been made on all Ham bands from VHF to
24GHz however 2 metres is the most popular band since it is the easiest
to build or buy equipment for. Some EME activity is now occuring on the 6 and 10 metre
bands. Elevating antenna arrays for the lower frequency bands is more difficult due to their sheer
size and wieght so many of the successful EME contacts on these bands occur using the over-the-horizon method.
- Until recently, most EME communication was done in CW (Morse Code) since it it easier to hear a weak tone than it is
to distinguish a weak voice signal. Single SideBand (SSB) voice communication is possible but generally limited to "Big Guns" with
large antenna arrays and lots of gain. Digital mode, using a computer running WSJT software is now the most popular mode of EME
since it requires far less gain than CW or SSB, allowing smaller stations to participate.
LINKS:
Very informative EME web pages:
W5UN's EME Primer
K7XC's 144MHz EME Basics
The reality of One-Way EME conditions well explained by N1BUG
Useful EME tools:
Moon Rise/Set Calculator
W5LUU's Moon Data Calendar
CW EME Activity Logger
JT65 EME Activity Logger
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