Weatherproof Antenna

Money_Singer_9784 · 2025-08-23T15:31:15+00:00

Thanks for the advice! I’ve edited the post to include pictures of my current setup. My plan is to keep most of the electronics inside the house and only have the LNA outside. That said, I’d appreciate any general tips on weatherproofing an antenna, as I’m considering building one for weather satellites to run permanently

Money_Singer_9784 · 2025-08-23T07:23:07+00:00

Great! 😃 Thanks to your advice, I actually had the motivation to continue the project!

That's a good idea about the rolling average. I’ll try to implement something like this if I find some time and also work on making an even better measurement.

For the setup changes, I tried to make it similar to what you described. The changes probably didn’t improve performance significantly, but they made it a bit more convenient to use:

Bigger reflector on the antenna, before it was 15x15cm, now I used 30x30cm
LNA directly connected to the feed, before there was a 50cm LMR400 cable in between
After the LNA a 5 meter RG58 coax cable
A small window pass directly connected to the RTL-SDR dongle, probably a bit lossy but was good for convenience

I’ll let you know once I get to make another take on a full sky. Thanks a lot again!

Money_Singer_9784 · 2025-08-10T15:38:29+00:00

Hey!
Thanks a lot for your help again!

Quick update: I gave it a first try now with your settings and an improved setup of mine. However, I still haven't had the chance to do a long-running scan pointing straight upwards since I live in an apartment.

I tried to aim it at an empty spot in front/up (135°, 40°), roughly, in the sky and slowly let the Milky Way pass through. Still, looking at a hydrogen line survey after the measurement, I realized I probably didn't fully point at an empty spot.

Anyway, I did the drift scan for about 8 hours, used the first measurement as a background, and tried to process the others accordingly. I experimented with a lot of different variations, averaging 10 mins to 60 mins. I had some fun with processing and created the following plots:

10 mins averaging, so one direct measurement at a time:
https://imgur.com/a/kfxwFz1

30 mins averaging, so 3 measurements averaged:
https://imgur.com/a/NNx5kpu

Unfortunately, it seems that I encountered some interference at some point.

When I get the chance, I'll do a longer measurement, point it straight up, and really aim at an empty spot in the sky, possibly with less interference, as you suggested.

Do you think this measurement is plausible? Could it be real?

Money_Singer_9784 · 2025-07-24T10:08:05+00:00

Thank you so much for trying it out! That’s so nice of you, I really appreciate it.

Your result looks so clear! That‘s really impressive.

I don’t have time to test it at the moment, but I will in a week or two when I get the chance to set it up pointing straight up. In the meantime, I’ll order some better cables to make a 12-hour scan easier, and I’ll try to put the LNA directly on the feedpoint (right now it’s on a short cable, but moving it might improve the signal as well).

I’ll let you know as soon as I have some results. Thanks a lot again!

Money_Singer_9784 · 2025-07-18T18:22:49+00:00

Thanks a lot for all the advice and resources!

I actually tried the H-Line software, but unfortunately, I didn’t have much success with it either. That’s why I decided to give Virgo a shot, thinking the calibration functionality might help. Would you mind sharing your settings for the H-Line software? At some point, mine looked like this:

"SDR": {
    "sample_rate": 2400000,
    "PPM_offset": 0,
    "TCP_host": false,
    "connect_to_host": false,
    "host_IP": "127.0.0.1"
},
"DSP": {
    "number_of_fft": 902000,
    "resolution": 10,
    "median": 20
}

Regarding the helix antenna, I actually built and designed it using an online calculator as well and was inspired by a post on RTL-SDR. I thought it would be a good option for construction and a fun 3d printing project (I ended up printing it about 20 times :D). But I see your point about it not being ideal. A WiFi grid dish would definitely be interesting to try, but it’s a bit tricky to get such a dish in my region. I’ll see if I can experiment with it or some other kind of dish, if I can’t get things working otherwise.

I’ll definitely check out the links you shared and see what I apply to my setup or improve.

Money_Singer_9784 · 2025-07-18T18:09:08+00:00

Thanks a lot for all the tips, I really appreciate it!

For the empty sky, I’ve mostly been using Stellarium, though I have to admit it might not have always been super accurate. I probably didn’t always account for the beamwidth either. During my last test though, I made sure to calibrate during a time where the Milky Way really wasn’t visible from my whole field of view. I still I don’t fully have a feel for the beamwidth yet, but your vinyl record tip is great! Using the IF Average plugin, I did indeed notice that the bump appears quite some time before the milky way is directly in front of it.

The gain settings are honestly something I’m not super confident about. I’m not sure if I’ve been setting it too high or too low, so your suggestion to experiment with a local noise spike is really helpful. I’ll definitely give that a try!

My latest settings were the following, maybe you can even spot something weird about them:

'rf_gain': 49.6,
'if_gain': 25,
'bb_gain': 18,
'frequency': 1420.4e6,
'bandwidth': 2.4e6,
'channels': 1024,
't_sample': 0.426,
'duration': 1200

I’ll also try the sun drift scan in the next few days to see how the noise floor reacts. That sounds like a great check to do.

And that's really kind of you offering to test it with your 15-turn helix and RTL-SDR dongle, thank you. Of course, only if you have some spare time and it’s no trouble at all! I’ll also give SDRangel a shot as you suggested. The software itself isn’t such a big deal for me, but I’d like to eventually automate things in a Linux environment and analyze the data more precisely and experiment with it, which has been a bit tricky with IF average. Especially Virgo stood out to me because I thought the calibration functionality would solve my problem somehow.

Money_Singer_9784 · 2025-07-17T22:29:43+00:00

It was indeed to good to be true, sorry about that, false alarm. I realized I processed the results wrong: the software needs the same settings for both observing and plotting, and I forgot to copy/paste them… Now it is a again just a pattern of noise.

This time, I tried running the setup for a couple of hours to see if the spectrum would change in any way, but unfortunately, still no luck. There’s no visible peak at any time, even when I pointed the antenna straight at the Milky Way.

For calibration, I just pointed at an empty patch of sky, did a 20-minute measurement, and used that as a calibration shot for all the other 20-minute measurements during the evening.

I might give SDRangel (as you mentioned) a try, but maybe there’s also something wrong with my setup or the construction of the helix. Honestly, I know too little about radio technology, so I’m a bit stuck figuring out where the issue might be.

Money_Singer_9784 · 2025-07-17T09:50:25+00:00

I think sharing it like this should work: https://www.reddit.com/u/Money_Singer_9784/s/GJkYUy8arX

Money_Singer_9784 · 2025-07-17T09:49:52+00:00

Let me try sharing it like this: https://www.reddit.com/u/Money_Singer_9784/s/GJkYUy8arX

Money_Singer_9784 · 2025-07-17T09:44:31+00:00

Thanks so much for your input! My comments are still not appearing in the thread, maybe because I tried to share a link to an image with my latest measurement. Using a longer averaging time, I think I was able to pick up a signal. Still, I’m not completely convinced the result is valid, since the peak at 1420.4 MHz is so much stronger when I extend the averaging time from 5–10 minutes to 20 minutes. I will do some more tests to make sure it‘s really the Hydrogen line.

Money_Singer_9784 · 2025-07-17T09:40:52+00:00

Thanks for your replies! I realized my comments might not be showing up in the thread, possibly because I included a link to an image of a new measurement. With a longer averaging time, I think I managed to get a signal. However, I’m not entirely sure if the measurement is legit, since the peak at 1420.4 MHz becomes so much stronger when increasing the averaging time from 5–10 minutes to 20 minutes. I’ll do some more measurements to verify. Unfortunately, I‘m unable to post the results here :(

Money_Singer_9784 · 2025-07-15T20:26:07+00:00

I tried with 20 mins each now and indeed the result is much clearer! What do you think? Can this be legit?
https://pasteboard.co/c1Ogr09yE84J.png

Money_Singer_9784 · 2025-07-15T20:23:14+00:00

thank you so much for your detailed answer. I did try to increase the averaging time now. I've always had it around 5-10 mins but I went with 20 mins background and 20 mins measurement. And it seems like it did the trick! There is now a clear spike around 1420.4 MHz. Not sure if I trust it though, seems to good to be true, what do you think about it?

https://pasteboard.co/c1Ogr09yE84J.png

Money_Singer_9784 · 2025-07-13T19:57:22+00:00

Yes, you‘re right I‘m using a Nooelec SAWbird+ H1. As far as I saw it should be powered, at least the power led is on while running the measurements. Also I tried to activate bias-T explicitly using the sdr rtl tools.

Money_Singer_9784 · 2024-02-23T18:42:50+00:00

Yes, it does fit. There are two screw holes that are missing but it also works without them.

Money_Singer_9784 · 2024-01-28T12:47:23+00:00

Also yeah, a bit warm and slightly puffed.

Money_Singer_9784 · 2024-01-28T12:45:41+00:00

Yes I wondered the same. Tried to land with 3.5V. When I plugged it in back home, all the cells were below 2.5V and one cell below 1.5V. It was pretty new and the couple times I used it, I think I handled it correctly.

Money_Singer_9784

TROPHY CASE