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With barely no knowledge in this field, I would like to render my antenna used with Bluetooth BLE devices more directional.

I tried to shield the antenna with different kind of metals with no luck.

Is there someone to point a way in order to render my antenna directional? Perhaps surounding with something?

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  • $\begingroup$ Hi sdespoint, welcome to Amateur Radio StackExchange. I think you tried to post a link in your question but it is not showing up correctly -- could you edit your post and add the link so we can see what antenna you are talking about? Thanks! $\endgroup$ – mtrberzi Oct 24 '14 at 14:29
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The antenna you link to appears to be directional (9dBi) already. If you can figure out where the main lobe of the antenna points (the specifications didn't seem to specify), you may simply try to aim more accurately.

An effective metal structure, in the manner I think you suggest, would probably be a fair-size satellite dish. 2.4GHz is around 12cm wavelength, so a dish would need to be several multiples of that, perhaps a meter or so diameter if I remember well enough. Anything smaller would be subject to diffraction and the radiation would just bend around the metal, perhaps even just reducing the overall radiated power due to losses.

Other modifications would require you to accurately space some sort of parasitic element to accurately re-radiate with the right phase. (Think of an outdoor TV antenna, or Yagi antenna) It may be easier to buy another antenna or build from scratch as you need to know more details about the antenna you already have, like its input impedance and radiation pattern, which changes when you put stuff around it.

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  • $\begingroup$ Thank you for your useful comment. I bought this antenna because of its directional characteristic. But, after some tests, it is absolutely not the case... $\endgroup$ – sdespont Oct 24 '14 at 19:43
  • $\begingroup$ What is the environment around the transmitter and receiver? You may have a lot of reflections disturbing your directionality. $\endgroup$ – James Palmer Oct 24 '14 at 22:36
  • $\begingroup$ Environment is a classic small office. Perhaps the signal bounce against the walls? $\endgroup$ – sdespont Oct 26 '14 at 8:27
  • $\begingroup$ This is a possibility. Wiring, steel structural elements, file cabinets, and desks are all able to reflect the signal. $\endgroup$ – James Palmer Oct 26 '14 at 12:16

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