Newbie antenna Qs

Useful information regarding antennas for SDR products.
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Newbie antenna Qs

Post by Strykar » Tue May 23, 2017 1:04 am


I'm new to this, please bear with my Qs, I'm upgrading to an RSP2 from a NoElec Mini2+

I live in an apartment in a tropical RF noisy city (FM/GSM/LTE), see heatmap:
However, I can mount 3 smallish antennas on a terrace mast (top floor flat, short coax run + higher elevation (than most neighbouring apartments) with a few miles of clear LOS).

I like to listen to ham bands, ADSB and NOAA APT/HRPT. I have a dedicated RTLSDR+antenna for ADSB.

I've never heard of lightning striking anything here but I have expensive PCs that are on a LAN and I'm worried about static/lightning blowing them up via the RSP2. I've discussed the grounding issue with an electrician here and he assures me my idea of grounding the antenna to the apartment ground will not work as expected for a direct lightning strike.

So an unwired (to my house) enclosure with the RSP2+filters+RPi/XU4 talking to me over wifi seems to skirt the "here's an easy conductance path to my PCs" issue, or so I think, please correct me if I'm wrong.

My Qs are in 4 parts:

1.Are these antennas good choices for an RSP2 ... tenna.html - HiZ port, would I need anything else to work this with the port? Port B + something like Adam's lna4all ... tenna.html - Add another bias tee power supply +LNA for NOAA

2. Would they perform well if I had them powered by solar+battery with no real ground except maybe the antenna mast? I was thinking PVC for the mast.

3. What protection against static can I buy that won't require grounding?

4. Would an FM band stop with built-in lighting surge like this be worth it and can I install three, 1 for each antenna? -

Since I plan to have an RPi3 or an XU4 my solar and battery setup will be large and I accept this compromise.
Any feedback is appreciated.
Last edited by Strykar on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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Re: Newbie antenna Qs

Post by robo-bal » Tue Jul 04, 2017 3:02 pm

I can't answer all your questions but I can talk a little about lightning. I am an ee and though not a specialist in lightning, I have an ex colleague who was. This is what I sponged from him.

For most residential buildings a direct lightning strike is likely a catastrophic event with lots of physical damage as well as fried electronics. The fault current will go where it wants to. It will jump across huge gaps to get back to earth and usually takes an unpredictable route, unless the grounding is engineered to protect against a lightning strike.

Even then it's a roll of the dice.

You can not really protect against this. Most residential grounds in North America are 10 AWG and will vaporise instantly and only manage to transfer a small amount of energy before heroically dyeing as an open circuit. The remaining energy finds and/or creates its own path. Strikes with 10 000A that lasts for a few milliseconds are common. That is a LOT of energy to dissipate. You will need redundant ground conductors of 2 AWG or 00 AWG - very expensive! Not to mention professional installation by a qualified person.

What can usually be protected against is damage cause by near strikes. This will include line voltage surges and radiated or induced fault currents. That's why most lightning 'protection' devices are called lightning surge protectors. Even then, these devices can be useless depending on where the strike occurs and how much energy is released.
Last edited by robo-bal on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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Re: Newbie antenna Qs

Post by Mike2459 » Thu Sep 14, 2017 5:19 pm

Low/No cost lightning/surge protection: Physically disconnect antennas from the electronics when not in use

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Re: Newbie antenna Qs

Post by gearjamer468 » Tue Sep 26, 2017 4:32 pm

i agree with the lightning protection, there are adds in qst and other ham radio pubs ...

antennas, for hf, screwdriver antenna, magnetic loop, anything with a decent amount of wire, also an antenna tuner will be good ...

vhf / uhf,, discone for general use, small yagi,

satellite antennas, any of the turnstile type / egg beater

micro wave , small loop yagi , home brew coffiee can antenna / pringles can antenna

use your imagination and you tube
Last edited by gearjamer468 on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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