| Electronics > RF, Microwave, Ham Radio |
| 2.4 GHz link - best performance with one antenna H and one V! WTF? |
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| Delta:
I've got a cheapo analogue (PAL) CCTV camera in a shed, and I'm sending the signal to the house using a pair of cheapo 2.4GHz (analogue) A/V Tx/Rx boxes (not these actual ones, but you get the idea - http://www.accessories-shops.com/images/pdimg/WVT810BD.jpg The Tx is against a window, with the standard antenna. The Rx is in the loft, with a big Ebay Yagi on it. Distance about 20m. The internal roof is boarded and the roof tiles are quite hefty. Initially I set it up with horizontal polarisation (ie, the standard aerial pointing sideways, parallel to the house) and the Yagi also horizontal (elements parallel to the floor), my thinking being that most WifI routers use vertical pol. It worked OK, but I thought I'd try V, so I first moved the Rx Yagi to V, I notice the picture immediately got much better! Then moving the Tx ant to V (pointing it to the sky) the picture degraded! I've left it with Rx V and Tx H, and whilst I'm happy with the picture, the OCD side of me says this is not right! What is going on? |
| AF6LJ:
Surrounding materials will have an effect on your antennas performance. While you say you are using a yagi for your RX is it a yagi made up of dipoles or loops?? |
| Delta:
--- Quote from: AF6LJ on January 12, 2016, 01:58:15 pm ---Surrounding materials will have an effect on your antennas performance. While you say you are using a yagi for your RX is it a yagi made up of dipoles or loops?? --- End quote --- It's this kind of affair... http://en.arronna.com/imageRepository/850f6cf1-40aa-405f-b97c-83776bf328e3.JPG |
| PA0PBZ:
The polarization probably changes due to reflections and such. Stop worrying and enjoy. |
| AF6LJ:
--- Quote from: Delta on January 12, 2016, 02:04:36 pm --- --- Quote from: AF6LJ on January 12, 2016, 01:58:15 pm ---Surrounding materials will have an effect on your antennas performance. While you say you are using a yagi for your RX is it a yagi made up of dipoles or loops?? --- End quote --- It's this kind of affair... http://en.arronna.com/imageRepository/850f6cf1-40aa-405f-b97c-83776bf328e3.JPG --- End quote --- Okay Dipoles... I think the above post has the actual answer, not knowing your installation my best guess also would be the polarization has flipped due to reflections. |
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