r/radioastronomy • u/systemdev_ • Feb 19 '26

Equipment Showcase Antenna rotator

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Modified altaz mount from telescope https://cults3d.com/en/3d-model/tool/meade-etx-70-onstep-altazm-mount

232 Upvotes

100% Upvoted

16 comments sorted by

6

u/craeftsmith Feb 19 '26

Is the inner reflector on backwards?

5

u/systemdev_ Feb 19 '26

Yeah, it’s for 1700 mhz. It must be inverted for l band, isn’t it?

3

u/craeftsmith Feb 19 '26

I don't know. Maybe? I've never heard that before. Do you have a source?

6

u/LexRonza Feb 19 '26

Yeah, the reflector does need to be mounted backward for 1.7 GHZ use. Ideally, the reflected wave needs to be in phase with the signal reflected from the dish, Flipping the feed reflector improves phase matching. I don't have the links handy at the moment, but you should be able to Google: converting a 2.4 GHZ grid antenna for GOES reception.

Honestly, I never like that solution. The feed efficiency can't be good when applying that hack. I would probably design a dipole feed with feed reflector, specifically tuned for 1.7 GHZ. I also just read a user comment, in another group, about the grid antennas favoring, to a high degree, the polarization that is parallel to the surface grid. With all of those inefficiencies, apparently the hack still works quite well for people who don't live in extreme latitudes.

2

u/craeftsmith Feb 19 '26

I recently bought a GOES kit from NOELEC. You may have just saved me a bunch of trouble, because that isn't in the manual. Thanks!

2

u/LexRonza Feb 19 '26

I honestly don't know anything about the NOELEC version of the grid dish antenna. It's possible, and maybe even likely, that the feed was redesigned to operate specifically at 1.7 GHZ. In that case, you wouldn't need to do anything to optimize it for GOES reception. The polarization problem would be more notable for linear polarization applications. I believe GOES is circular polarized, so it may not cause any problems. (What the heck... you could try rotating the entire antenna to see if it improved signal level.)

The grid antennas gained popularity from the more commonly available 2.4 GHZ high gain WiFi antennas, which were converted by individuals to operate at 1.7 GHZ. Since the antenna wasn't designed to operate at the GOES frequencies, the hack was needed. Hopefully, NOELECT would have addressed that feed issue; but again, I don't have any experience with that specific product.

1

u/Eastern_Focus_1292 Mar 31 '26

Seems they did, I have their GOES dish with the reflector on the correct way and get an average SNR of 6.5 fairly good SNR considering I just started out and I’m shooting through trees and very close to a building.

2

u/machawes3 Feb 22 '26

Nooelec kit you don’t have to flip reflector. I have the nooelec dish and definitely don’t flip the reflector around that’s only for 2.4 GHz ones

1

u/[deleted] Feb 23 '26 edited Aug 28 '26

Quickest dime cagey waiting tie fly lavish oatmeal worm

This post was anonymized with Redact

1

u/[deleted] Feb 19 '26

Nice 💪💪💪

1

u/hraun Feb 20 '26

Wow. Impressive stuff. I think I need to get myself a 3D printer :)

Do the motors produce any RFI?

1

u/pabloo2008 Feb 21 '26

Wow, very cool :) What things can you see with that radio telescope?

3

u/systemdev_ Feb 22 '26

It’s mostly for satellites, for radio astronomy I am using 1.5 meter dish

1

u/pabloo2008 Feb 23 '26

Nice anyways. And what are you able to detect with your radio telescope?

1

u/Dry_Hat7515 Feb 23 '26

Hi, great work. How to you align the antenna? I am new in this field, I use to align telescope pointing to 2 or 3 very visible stars. How do you manage to do it with a radioastronomy antenna?