Sources for antennas?

Discuss KerberosSDR - 4x Coherent RTL-SDR
StandingWave
Posts: 29
Joined: Fri Jul 27, 2018 1:00 am

Re: Sources for antennas?

Post by StandingWave » Tue Apr 16, 2019 9:09 am

Hi folks!

Just received my KerberosSDR the other week. I don't have that much of experience in the amateur radio field. I have a RTL-SDR that I've used with SDR# for less than a few years. That being said, I've worked in the IT & A/V tech field for multiple decades and hence, I was wondering ...

I forgot to purchase the required antennas to go with the KerberosSDR, and am now waiting for some cheap ones to arrive to try them out - ordered four of those that someone suggested on this thread at around ~5 USD each.

Today, I began to look around my storage room and noticed that I have a bunch of old wireless routers, repeaters and other wireless units laying around, all of them are with multiple identical antennas that are detachable and apparently with an SMA connector. (LinkSys, Cisco ...).

The Linksys ones that I had around seem to be using a RP-SMA (Reverse Polarity SMA) connector, https://en.wikipedia.org/wiki/SMA_conne ... e_polarity so they're out of the question unless there's a way to reverse that polarity.

The other wi-fi related gear with detachable antennas in them, however (i.e. the ones from some of my other brand repeaters and 2,4Ghz Wi-Fi CCTV's) seem to have just the correct SMA type and polarity.

So, what I wanted to ask - and pardon the stupid question in advance - is whether or not any of those router/wireless SMA connector-equipped antennas would be of any use for a trial run with KSDR - just for a rough initial test while I'm waiting for my "proper antennas" to arrive?

Is there a risk of something irreversible if I use those antennas from the wi-fi devices with the KSDR? I would make sure beforehand that they're all identical, etc. The ones I've tried connecting (note: without the device turned on) seem to fit well into the unit's SMA connectors, so at least they fit.

Since I'll rather be safe than sorry, I'd like to know what is your take on if it's a good idea or not to use those types of antennas even for a test run of the KDSR -- i.e. can there be some impedance problems, something that a newbie like me doesn't take into account? (Serious signal quality degradation/interference, unsuitable reception/SnR troubles, overheating/incompatible antenna type, causing something to go haywire big time, etc ...).

All the antennas have a built in L-knee in them, so that I can bend them to point upwards from the back of the unit. At least they'd then be in a perfectly measured array! :lol:

Anyway, all help kindly appreciated. Thanks.

StandingWave
Posts: 29
Joined: Fri Jul 27, 2018 1:00 am

Re: Sources for antennas?

Post by StandingWave » Tue Apr 16, 2019 9:20 am

Seems like I should've googled the subject matter up more thoroughly before asking. Albeit this one's only for the RTL-SDR, I'd reckon some of the basics apply to KSDR as well - https://www.reddit.com/r/RTLSDR/comment ... r/?depth=1

I have an assortment of aerial adapter patch cables straight from RTL-SDR, so I think I'll just try the KSDR out by hooking it up to i.e. my 75 ohm television antenna. Cheers! :geek:

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kb3cs
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Re: Sources for antennas?

Post by kb3cs » Tue Apr 16, 2019 11:45 am

yeah, what's hiding under the cover of random wifi antennas might be cheap and simple (good for RTLSDR) or it might not be (bleah but not 'dangerous' or 'irreversible' for RTLSDR). "it depends" is the best technical answer, unfortunately.

rtlsdrblog
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Re: Sources for antennas?

Post by rtlsdrblog » Wed Apr 17, 2019 2:20 am

Remember that if you're using it for DOA you'll need to have the antennas arranged in a certain pattern with certain spacing.

Using a whip antenna won't hurt the unit though. Although as you've already seen, WiFi antennas typically use RP-SMA connectors which won't work here.

Username
Posts: 402
Joined: Sun Oct 09, 2016 7:27 am

Re: Sources for antennas?

Post by Username » Wed Apr 17, 2019 7:53 am

Does anyone know a good source for a Radom?
I will maybe buy a Bike and that is a good option to put a Radom in a Trailer and scann arround. :D

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kb3cs
Posts: 34
Joined: Thu Apr 04, 2019 2:15 pm

Re: Sources for antennas?

Post by kb3cs » Wed Apr 17, 2019 12:00 pm

some wifi antennas are simple bits of wire, others might have coils and/or bits of transmission line to phase antenna segments (gain and radiation pattern considerations). the former is (as i said previously in this thread) good for RTLSDR and the latter is bleah.

ps: for radome ("ray-dome") material, see:
https://www.edaboard.com/showthread.php ... r-a-radome
and
https://www.generalplastics.com/technic ... se-radomes

Username
Posts: 402
Joined: Sun Oct 09, 2016 7:27 am

Re: Sources for antennas?

Post by Username » Wed Apr 17, 2019 1:19 pm

That is the lowest freq where the work? :o
And i look for a finish product.

PistaP
Posts: 1
Joined: Mon Jul 22, 2019 4:22 am

Sources for antennas?

Post by PistaP » Mon Jul 22, 2019 7:11 am

I had installed a circular antenna array on the car roof clockwise as in the manual or on the video, but the bearing was shifted 180 degrees. Then I installed the antenna array counter-clockwise so the azimuth was correct. Where is the problem? either in the software or in the manual.

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