NOAA APT 137MHz DIY antenna only with 75Ohm coax

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AlarmedFelix
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Joined: Wed Feb 21, 2018 5:12 pm

NOAA APT 137MHz DIY antenna only with 75Ohm coax

Post by AlarmedFelix » Wed Mar 28, 2018 1:16 pm

Hi guys i need help i want to build myself antenna for 137MHz circular polarization but i dont have 50Ohm cable so can somebody tell me is it possible to create antenna for NOAA without 50 Ohm coaxial cable and dipole i already have.




I KNOW 50OHM CABLE COST FEW DOLLARS BUT I DONT WANT RIDE TO THE CITY.

rtlsdrblog
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Re: NOAA APT 137MHz DIY antenna only with 75Ohm coax

Post by rtlsdrblog » Thu Mar 29, 2018 1:00 am

Yes 75 Ohm cable will work fine.

AlarmedFelix
Posts: 23
Joined: Wed Feb 21, 2018 5:12 pm

Re: NOAA APT 137MHz DIY antenna only with 75Ohm coax

Post by AlarmedFelix » Thu Mar 29, 2018 9:06 am

OK thanks. I am asking because i saw 75 Ohm and 50 Ohm cables combined for some antenna (Turnstile, Cross Dipole etc.)

snn47
Posts: 221
Joined: Tue Dec 27, 2016 11:00 pm

Re: NOAA APT 137MHz DIY antenna only with 75Ohm coax

Post by snn47 » Thu Mar 29, 2018 6:59 pm

OK thanks. I am asking because i saw 75 Ohm and 50 Ohm cables combined for some antenna (Turnstile, Cross Dipole etc.)
The 70 Ohm cable is normally used only for phasing purposes when combining the two dipoles, while the feeding cable is 50 Ohm. Check HAM Radio literature, e.g. ARRL antenna handbook for more information for building antennas.

You can also check out for QFH antennas.

AlarmedFelix
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Joined: Wed Feb 21, 2018 5:12 pm

Re: NOAA APT 137MHz DIY antenna only with 75Ohm coax

Post by AlarmedFelix » Thu Mar 29, 2018 9:41 pm

snn47 I am trying QHF antenna right now iam waiting for next pass of some NOAA satellites but i like METEOR sat. more.

Username
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Re: NOAA APT 137MHz DIY antenna only with 75Ohm coax

Post by Username » Fri Apr 06, 2018 10:15 pm

How about other Antenna Design?
I will build an Antenna to. There are some Helix Antenna who look nice does the have an besser Gain?

rtlsdrblog
Site Admin
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Re: NOAA APT 137MHz DIY antenna only with 75Ohm coax

Post by rtlsdrblog » Sat Apr 07, 2018 4:11 am

Helix antennas are emuch more directional. Only really useful if you have a tracking mount set up to follow the satellite as it passes over.

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Re: NOAA APT 137MHz DIY antenna only with 75Ohm coax

Post by Username » Sat Apr 07, 2018 9:23 am

I found some HowTo. But which one is the best? My Problem is if I want get the best result the Antenna must be place on the Roof who I cant get there and the Antenna could only replace in Summer when the Roof is dry. :roll:
https://www.motherearthnews.com/nature- ... az93onztak
https://www.dxzone.com/dx30769/double-c ... tenna.html
https://www.aeronetworks.ca/2017/12/
http://tinhatranch.com/how-to-build-a-q ... atellites/

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Posts: 611
Joined: Sun Oct 09, 2016 7:27 am

Re: NOAA APT 137MHz DIY antenna only with 75Ohm coax

Post by Username » Mon May 07, 2018 10:35 am

So I got some thick and stiff Copper Wire (its for an Ground Connection) on a 20m Coil and I am ready to get my finger dirty. :D
So what is the best design for the Weather Sat? An well known Helix Antenna?

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