Poor performance with DIY antennas

The uptrend yesterday which can be seen on your remaining receiver is not unusual for a friday, or?

I have a similar increase as well for that day without changing anything. You might need to monitor this for at least a week.
You have also an uptrend on # of messages, but in your history you had these improvements also (e.g. 02/14)

Your station above, mine below:

After running each antenna for 24h, the whip still wins by a large margin:

whip (area covered 80kkm2, max range 275km)

coax spider (area covered 50kkm2, max range 247km)

cantenna (area covered 58kkm2, max range 253km)

I’m getting slightly annoyed by this so I decided to bite the bullet and ordered nanovna-h4 :slight_smile: it should be with me in a few weeks.

Assuming I’ve built the antennas properly, the only other difference I can see is the coax. The whip is on magnetic base with 2m of RG58, while for the DIYs I’ve used RG6 but much shorter lenght, would that make such a huge difference?

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see this link re rg58 vs rg6 for ads-b applications

For the price of the nanovna you could simply buy an optimized FA antenna.
I have no idea what issues your setup nas.

At the beginning i was the simple whip antenna, then i built a spider made from a simple coax with arms in correct length. I did not use any electronic device, however it outperformed the whip by at least 30%

Now i am using an optimized antenna i got from ebay for low price - done.

I could, but where would be the fun in that?:slight_smile:
I’m not after highest feeder ranking, I’m doing this for fun and to learn something.

Exactly! I was expecting at least some improvement but got even less. I want to find out why.

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Some antennas pick out-of-band signals stronger than other antenns, and therefore pick more TV and Cell Phone signals, causing overload of dongle and poorer performance.

Have you run a frequency scan for each antenna? The guide to scan is here:

Do I Need A Filter?



I didn’t, but the blue FA stick already has 1090MHz filter. I have a FM bandstop as well, I might try that.

EDIT: I’m running the scan
the whip


Your mag base does not use RG58
If assembled correctly, quality RG6 is significantly better than RG58 at microwave frequencies.

Awaiting results with your NanoVNA with interest.


Right. It uses RG174, which is single shielded.


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That’s what you did not write so far :wink:

Which is even worse at 1GHz than RG58

It does:

(I was positively surprised)

But it still doesn’t explain why the whip performs better:)

I’m rebuilding SO239 spider using crimp terminals instead of soldering. I had to really crank up the iron last time so maybe the head damaged the connector.

Theres a lot of ways to build them using less expensive bits, I ruined a few SO239 connectors trying to make pretty solder joints. :wink:

Here’s one I made using a simple F coupler connector, simply winding the ground plane radials onto it and tightening the nut. Simple, works fine doesnt really need to be soldered but I sweated the two pieces together.

Another I made using a copper plumbing pipe cap, drill four holes at the upper edge to solder the radials into and a center hole to insert an sma to F pigtail through it. Copper of course takes solder well. BTW, I did experiment some with the height of the ground plane on the connector and it didn’t seem especially sensitive to that.

My Spiders





Nature’s Spiders

All 8-legged

spider 8 legs -1 spider 8 legs -2 spider 8 legs -3 spider 8 legs -4

Arachnovations ? :smiley:

That’s hard to argue with, I’m impressed!
Is it this cable?
It’s an odd choice as it’s neither low loss like an LMR/LL nor conveniently flexible like RG174

Yes, it’s antenna from nooelec bundle.

Anyway, I think I did it this time!

My rebuilt spider:

I only had it running for few hours but max range is the same (275km) and area covered is slightly bigger (81 vs 80kkm2). I’ll have to wait another 12 hours to fully compare the stats.

Things I’ve changed:

  • crimp connectors instead of soldering
  • 2.5mm2 copper wire instead of 4mm2
  • 2m RG58 instead of short RG6

The first two points shouldn’t have much effect right?
Could I have just dodgy batch of RG6?

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That’s possible, or the connectors didn’t work properly.

As i wrote before you really want to test reducing whip length gradually.
I have had much better luck with 62mm or shorter whips, measured from the shielding.

Did you terminate the RG6 yourself? Is the RG6 quad shield? I think quad shield can be a problem if not terminated correctly.