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433 Mhz Yagi

 
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prioryjim
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Joined: 30 Dec 2014
Posts: 2

PostPosted: Tue Dec 30, 2014 7:54 am    Post subject: 433 Mhz Yagi Reply with quote

Hello
I have a 433 Mhz receiver thus

http://www.rfsolutions.co.uk/acatalog/info_AM_HRR3_433.html

And an associated transmitter.

They both have a simple vertical copper wire antenna

They work 100% at close range.
With one in my greenhouse (20 metres away) the reception is intermittent.
I tried a DIY Yagi thus

http://www.instructables.com/id/433-MHz-tape-measure-antenna-suits-UHF-transmitte/step4/Alternative-DIY-UHF-Yagi/

But it seems even worse.
Should it be vertical or horizontal ?
Comments/suggestions please
Thanks
Jim
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admin
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Joined: 03 Jan 2007
Posts: 201

PostPosted: Wed Dec 31, 2014 8:21 pm    Post subject: Reply with quote

The good news is, if the reception is intermittent at 20 miles that means nothing is catastrophically broken.

As for what works in your scenario, you'll need to experiment. The only quick rule of thumb is the higher you mount your antenna, the generally better off you'll be. You can try both vertical and horizontal polarizations, but generally i think horizontal works better. Just make sure both your transmit and receive antennas have the same polarization.
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prioryjim
Antenna-Theory.com Newbie


Joined: 30 Dec 2014
Posts: 2

PostPosted: Thu Jan 01, 2015 7:02 am    Post subject: Reply with quote

Thanks for the reply.

20 miles ( it's 20 metres )

Anyway I did some more research and discovered my error.
I had the second element with the coax as a single solid bar like the others.
The coax centre was connected but not the shield.

So now the second element is cut in half and separated, coax on one part and shield on other.

Now works a treat at distance of 20 meters with TX in Greenhouse and RX Yagi in back bedroom through window and curtains.

The element is vertical.

Regards
Jim
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