EME on 11meters sked wanted

[Superidgit]

I know about ground gain and apogee versus perigee and that in some cases the angle of elevation of the moon is relevant however my post above was in relation to Superidgit's post where he said:

"If a person could keep the angle from transmission point to moon to recieving point as close to 90 degrees as possible. Could the signal stand a chance then, with what is being proposed?"

When you look at the geometry of the distances involved, you would never be able to achieve a 90 degree angle with the moon at the apex of the angle formed by TX-moon-RX. That is the angle I was talking about, not elevation angle of transmission to take advantage of ground gain at moon rise or moon set.

Ahhh I see what you are getting at now. I also understand what you said when the signal hit the surface of the moon, the signal would scatter all to hell and gone. I guess what I do not understand is what would make 11m so impossible compared to other frequencies? Is it just a coincedence that the 11m frequency and Nature dont get along?

 

[wavrider]

Reflection, refraction, and filtration.
HF would be hard to do with moon bounce,BUT given the right circumstances, right antennas and enough watts it may be possible.

It would be one hell of a stacked phased yagi array to accomplish this, some think like four 6 element yagis stacked vertically and horizontally just to come close to getting the gain to do EME bounce.

Guess it could be done, Heck some op made a 160 meter yagi so why not a set of four or eight 6 element 11 meter yagis phased to do EME.

‪OH8X: 160M 3 ELEMENT YAGI‬‏ - YouTube

‪OH8X - 160M 3el yagi rotated‬‏ - YouTube

 

[Mudfoot]

I think if it could be done...

It would have been tried by now.

 

[Wire Weasel]

I guess what I do not understand is what would make 11m so impossible compared to other frequencies?

It's not impossible SI. But go back and look at page 1 and see the multi-stacked UHF array the guy is using. That is the TYPICAL sort of setup for EME attempt. It's doable as UHF antennas are much smaller. The elements are very short. Yet they're still very long and have a high number of elements per individual beam. They're stacked and double stacked. That is the kind of directivity and gain needed to reach the moon. Pic on first page I count 8 of what looks like 26 element beams.

11 meter beam elements are 18 feet long! (9 foot per side). A 4 or 6 element beam doesn't have enough gain to go for the moon. Imagine trying to construct a multi-stacked high-number-of-elements beam. It would be as big as a house. It would require a custom commercial grade azimuth type rotor to lift and turn the monster. The rotor alone would cost tens of thousands of dollars. Then you would still need a large amplifier and sophisticated RX preamp to generate and receive the signals. So think about what an 8 stacked 26 element 11 meter beam array would look like. Probably more like two houses.

It's just too physically large to be practical. It would require a rich person with years of time on his hands. And then you're going to need two or more such people in different places doing the same thing to have someone to QSO with.

Ain't gonna happen. Not can't happen.....just ain't gonna happen. Anybody who thinks you can "work the moon" on just a couple of 6 or 8 element beams is foolin' himself.

 

[Superidgit]

It's not impossible SI. But go back and look at page 1 and see the multi-stacked UHF array the guy is using. That is the TYPICAL sort of setup for EME attempt. It's doable as UHF antennas are much smaller. The elements are very short. Yet they're still very long and have a high number of elements per individual beam. They're stacked and double stacked. That is the kind of directivity and gain needed to reach the moon. Pic on first page I count 8 of what looks like 26 element beams.

11 meter beam elements are 18 feet long! (9 foot per side). A 4 or 6 element beam doesn't have enough gain to go for the moon. Imagine trying to construct a multi-stacked high-number-of-elements beam. It would be as big as a house. It would require a custom commercial grade azimuth type rotor to lift and turn the monster. The rotor alone would cost tens of thousands of dollars. Then you would still need a large amplifier and sophisticated RX preamp to generate and receive the signals. So think about what an 8 stacked 26 element 11 meter beam array would look like. Probably more like two houses.

It's just too physically large to be practical. It would require a rich person with years of time on his hands. And then you're going to need two or more such people in different places doing the same thing to have someone to QSO with.

Ain't gonna happen. Not can't happen.....just ain't gonna happen. Anybody who thinks you can "work the moon" on just a couple of 6 or 8 element beams is foolin' himself.

WW thank you for your input it has certainly shed some light on things for me and thank you.

However I look at those pics you asked me to look at. They look like stuff thats been manufactured then put together. All the other things I read about and see show pretty much the same thing.

Out of the box ... could not something be homebrewed ( if I had the time and the place I would try) just specifically for TX and RX EME? or is this one of those things that everyone says " nothing travels faster then the speed of light"?

 

[Wire Weasel]

WW thank you for your input it has certainly shed some light on things for me and thank you.

However I look at those pics you asked me to look at. They look like stuff thats been manufactured then put together. All the other things I read about and see show pretty much the same thing.

Out of the box ... could not something be homebrewed ( if I had the time and the place I would try) just specifically for TX and RX EME? or is this one of those things that everyone says " nothing travels faster then the speed of light"?

Homebrew - manufactured.....doesn't make any difference. Size is size. 11M yagi beam elements must be 18 feet long. And it's going to take a shitload of them put together to create enough gain to reach the moon.

I guess you don't understand.......

 

[towerdog]

Just about anything hams do on 10 meters, us pirates can do on 11. All we gotta do is add 1 meter right?

Good luck man, a 6+ element yagi array would be quite awesome. Think about SETI's dish, thats a parabolic dish capable of HF frequencies. http://cache.wists.com/thumbnails/1/a6/1a6919d1ab81e55ac20dc3094cd3befe-orig

BTW, first time I ever heard of EME it was from a ham who did it on 2 meters, cw AND SSB modes, with an yagi antenna that resembled a roll up fire escape ladder.

I think on 11m, run higher power to make up for less elements, like 5,000 watts or more.

 

[Wire Weasel]

 

[Captain Kilowatt]

Good luck man, a 6+ element yagi array would be quite awesome. Think about SETI's dish, thats a parabolic dish capable of HF frequencies. http://cache.wists.com/thumbnails/1/a6/1a6919d1ab81e55ac20dc3094cd3befe-orig

That's not a SETI dish actually nor is it useful on HF unless you meant just it's shear size.It is used as a radio telescope. The lowest frequency that dish in Arecibo is used is on 47 MHz where it has a 300 Megawatt ERP. The same dish used on 2.3 GHz has an ERP of 20 TERRA watts. I pity the poor birds that pass in front of the main beam of that thing.

http://en.wikipedia.org/wiki/Arecibo_Observatory


BTW, something no one has considered is the higher noise floor on 11m than on any of the VHF or UHF bands as well as the (relatively) poor sensitivity of the average 11m gear. Most EME contacts are made using high performance receivers with GAsFET frontends and preamps.

 

[Wire Weasel]

BTW, something no one has considered is the higher noise floor on 11m than on any of the VHF or UHF bands as well as the (relatively) poor sensitivity of the average 11m gear. Most EME contacts are made using high performance receivers with GAsFET frontends and preamps.

Exactly. And another thing not specifically mentioned but certainly implied is what you are doing here is known as Weak Signal Work. The average distance to the moon is 289,000 miles (google) Talk about weak signal work! That is why GIANT antenna arrays with huge power outputs and extremely enhanced receiver networks are required for EME.

So these projects are not for the feint of heart or light of wallet.

 

[kd-5-bgt]

The hard part would be getting the signal out of the atmosphere...11 meter signal will usually bounce back to earth instead of heading out to space...

That is why hams normally use VHF/UHF for EME work......

and EME work is heavy on the wallet ...but it can be done...just not sure if 11 meters will let ya though

 

[cbradiomagazine.com]

Here's an article about a guy who's got a big dish at his shack - Ham radio far from over or out

 

[towerdog]

one of my future projects that i hope to finish before my hair turns grey and falls out is a monster yagi for 11m. They exist, I have seen very large examples of the yagi while inspecting radio towers. I saw one that measured over 20 feet out, with a cable helping to support its weight, an ungodly thing which was part of an arry of more ungodly antennas, all of it abandon and I presume was a studio to transmitter link considering the tower was at a studio.

 

[Henry HPSD]

Am i misinterpertating about a the large beam? 20 feet is not big.

To give an idea what i know of that has been on the air oustide USA:

9el 80 feetboomlength Dutch guy
10el quad 60 feet boomlength Australia
2x 10el quad 56 feet boomlength Denmark,France
8el yagi 56 feet boomlength Germany
9el yagi over 100 feet boomlength (stack) Italy
There are maybe 5-10 guys running 7elemens yagi's with boomlength of rouglhy 55 feet wich i know of...including stacked ones.
And ofcourse not to forget the 6 elements with roughly 36 feeet boomlength...wich there are in really great numbers.

And i know i have designed quite a couple large ones for USA guys, "on the super bowl" .
I also helped guys in the USA with large commmercial beams and "corona" problems. That problem only exsisted if they ran over 15 Kw !

So, i honestly think there are some bigguns outthere capable of eme.

Back to EME, in the old days it was needed to have a really large stack in order to pick up a signal. But now a days with JT65 modes, all the above mentioned stations are suitable for EME. (running a couple Kw) A larger antenna system will help ofcourse.

@wireweasel,
Your interpertation about "anyone who thinks they can work the moon with a single 8 elments is fooling themselves" ....is to my believe inaccurate.
The Germans already provided proof for that for 11 meters
Besides you wouldnt believe how many HAMS have used single yagi's on 6 meters for eme work
And i believe your avarage distance to the moon migth be inaccurate aswell.
But thanks for the critical note! it is always appriciated.

Now, we already have the first station to give it a try.
Some small changes need to be made, so as it looks like now..this winter we are going to give it a go.

Anyone else?

Kind regards,

Henry
www.dx-antennas.com

 

[Robb]

Henry:

Just how are you going to do your beam for this project; just what kind of equipment do you have in mind?
Details?

Thanks . . .