Re: How do I limit my RF reception range?

Brad Kartchner wrote:
Hello, everyone!

I'm working on a project that requires wireless communication between
two devices but only within a small distance (2-3 feet at most). I
have settled on an using RF (2.4 GHz) to communicate between them, but
need to be able to limit my range.

Would tuning my antenna to a harmonic of 2.4 GHz work? Or would this
result in an unreliable communication link? I know antennas are VERY
complicated, but could I just play with reducing the length of the
antenna?

Any help would be appreciated.


3 feet is not very far. For example, I have a Laipac 434 MHz receiver whose specs say it has a -100 dBm sensitivity. This receiver, with a 1% efficient antenna, should almost be useful at 3 feet from a transmitter when putting 10 microwatts into its 1% efficient antenna.

Assuming you are using a low-power transmitter which will not be hurt by its load:

1. Use a half-inch (or less) antenna to transmit (1/10 wavelength).
2. Use a use a receiver with terrible sensitivity.
3. Use a half-inch (or less) antenna to receive.
4. Adjust a combination of the above to get the range you desire.

Due to reflections and other variations, I think it will be a bit difficult to adjust the range to between 2 and 3 feet and expect reliable operation. But, please let us know if you achieve this and how you do it.

Good luck.

John
.

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