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I'm doing a project with a Bluetooth device for the first time, specifically with a JY-MCU Bluetooth module:

enter image description here

As you can see, the antenna is on the green PCB, which is in turn soldered to a breakout board.

Does it matter what orientation the antenna is in? For example, I could set it flat on its top or back as shown in the above image, or I could also plug it in vertically.

Will changing the orientation change the receiver and transmitter distance?

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    \$\begingroup\$ Yes it does, but you may not have control of the orientation of the final unit. You hope to tolerate the variation, or to reorient the unit so the gain is better. Although they try to be omnidirectional, they are not. \$\endgroup\$ – Ross Millikan May 22 '14 at 22:57
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Yes it does, in contrary to other answers. It's not an isotropic antenna and will have more gain in one direction than another. This affects transmission distance. Using the example shown in aloishis89's answer there is clearly a 10dB difference in antenna gain in one direction compared to another. Using the Friis Free-space formula for link loss: -

Link loss (dB) = 32.5 + 20 log(MHz) + 20 log (kilometres)

If the link loss was made 10 dB greater by misalignment of the antenna clearly this affects the distance that the receiver can be placed away from the transmitter. A 10dB increase in link loss can be "recovered" by shortening the distance between the two antenna to 31.6%

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Edit: I was wrong, it can. Here's a picture of a similar antenna:

enter image description here

And here's it's radiation pattern: enter image description here

The radiation pattern is a polar plot of the relative gain of the antenna at each angle. As Andy aka and mouseas pointed out, this plot is in dBi, which is a logarithmic unit (it's dB relative to an ideal isotropic antenna). That means that in some directions, the gain is 10x better than others. Keep in mind that this antenna isn't exactly the same as yours, but it looks like you may see an appreciable difference depending on orientation.

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    \$\begingroup\$ Is the distance from the center of your second graphic a linear or log scale? It looks logarithmic, and if that's the case, you're looking at a 10x reduction in signal strength from best to worst. \$\endgroup\$ – mouseas May 22 '14 at 20:54
  • \$\begingroup\$ dBi is a logarithmic unit of measure, so you may very well be right. \$\endgroup\$ – Kenogu Labz May 22 '14 at 22:36

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