Mesh dish for 3cms eme

[VK6RK]

Has anyone come across a commercially available dish of 2 to 3 mtrs dia with a mesh size suitable for it to be used on 10 ghz please.
Or even a 2.4 mtr offset feed solid one?
I have no restriction on dish size out at the club, but I want to duplicate the system to use it at home as well.
I do have a 1.2 mtr prime focus I could use but would that be good enough ?
I've spent a couple of days chasing dead ends on the net so far
I dont need to re invent the wheel so I'd rather ask questions
73
Keith VK6RK / VK6EME

[VK3PF]

Keith,

Have a look at Charlie VK3NX's EME pages:
http://www.vk3nx.com/DishController.html

Charlie is using a 3.7m Joysat mesh dish on bands 23 to 3 cm.

Good luck with the project.

If you find a source of 2.4 m or similar size (or bigger size) offset dishes, please share the information!

Regards,

Peter VK3PF

[VK2XSO]

I have a nice ~3m solid spun aluminium dish not being used.
Problem is it's one piece and it's a long drive

I would think that you would be able to find plenty of 2.4m dishes in WA from the old Aussat days before the banana beams went into service.

[VK6RK]

Thanks for the feed back guys.
I've been measuring up and the largest dish I can actually fit on top of the 5 mtr mast is about 2.7 mtrs dia.
I had a look at Charlies pages and that gave me some ideas.
I think I might go for a mesh for now, then maybe I can get some use out of it on other bands later.
Out at the club we have a mesh 3.5 mtrs dish and a ribbed aluminium in a 1000 pieces that seems to be about 5 mtrs dia.
Its just the home setup that will give me probs.
I'm thinking of buying one of the new Alpha spid az/el rotators, the latest ones, that should work well at home here with a mesh dish.
Just need to think about feeds as well, for all the dishes !
I'ts nice to be back involved in mWaves after a 20 year break !
I'd forgotten how much fun it can be, and of course, the challenges.
I regret selling both of my waveguide switches to Alan Devlin many years ago, they would have come in useful.
Thanks again, all feed back and suggestions are most appreciated.
73
Keith

[VK6RK]

Ok I have the option of a 2.4 mtr h/duty mesh dish, focal point feed or a solid 2.4 mtr offset feed dish.
Any advice on which is best for primarily 10 ghz ?
I'd prefer the offset if possible but I'm finding it difficult to source a feed for it, either one I can make myself or a bought one.
Again any suggestions please.
There does't seem to be much I can find on the net to help, I'm prob looking in the wrong places !
I've also just picked up an Alfaspid az/el rotator off moonnet for a good price so that will handle either comfortably.
Thanks in advance for any advice.
73
Keith
ps sorry to be a pain asking all these questions, he who doesn't ask, doesn't get !

[VK3ES]

Hi Keith,

An offset dish is easier to feed efficiently and will probably give better performance for EME, especially if you can arrange it so that most of the spill-over is directed away from the ground. I have a design for a suitable 10GHz feed that appeared in "Scatterpoint" some time ago. It is a dual mode horn made from two different diameter copper tubes (32mm and 36mm ID I think) and some WR90 waveguide. I can send you the article if you like, just drop me an email.

73,
Andy VK3ES
vk3es@wia.org.au

[VK3PF]

Hi Keith,

I would also go with the offset dish. As Andy says, they can easily be fed and have higher efficiency than the same sized prime focus (centre fed) dish - partly because there is nothing in front of the dish to block the RF coming to/from the reflector - the feed and the feed supports.

Have you looked at the The W1GHZ Online Microwave Antenna Book?
http://www.w1ghz.org/antbook/contents.htm

Also download HDL_ANT.exe from the bottom of the page. It allows you to determine the characteristics of the reflector and gives you the required characteristics for the feed, given some simple measurements from the dish. It will also help you to design a simple rectangular/pyramidal or cylindrical feed horn with the right characteristics.

Good luck,

Peter VK3PF

[VK6RK]

The 2.4 mtr offset dish turned out to be 2.8 mtrs and I cannot put it up where it needs to go to please the "boss"
Its also too heavy and too visual
I've grabbed it for the clubs 10 ghz activity at a later date so it seems I'm going with the 2.4 mtr mesh prime focus.
I also received today my qualcomm 10 ghz transverter , does anyone on here use one? If so I'd like to ask a bit of advice, perhaps direct?
73
Keith

[VK3HZ]

Hi Keith,

There are a number of variants of the Qualcomm. I run the so-called "lambchop" version with good results.

Happy to answer any specific questions - my email address is in the Opinfo section.

Regards,
Dave
VK3HZ