2.4GHz and 868MHz in one product

Hi,

Does anyone see any problems with using a 868MHz transmitter on a PCB which also has a 2.4GHz receiver?
I will also have the opposite configuration on another board.
I am sending A/V signals over 2.4GHz and control over 868MHz

Thanks.

Hi,

If you will filter each band, (really good filtering)
then u will not suppose to be in problem

David

The operative words were "on a PCB"!

Filtering will not do much good as the signals will just leak from one end of the board to the other.

I would separate the circuitry for the 868 radio to one edge of the board, and the 2.45 Ghz circuitry to the other edge of the board.

I would make sure there is a robust (at least 5 pole) lowpass filter at the output of the 868 circuitry. I would make sure there is a standard 2.4-2.5 GHz bandpass filter at the antenna port ofthe 2.45 GHz circuitry.

I would put a metal shield around the 868 MHz circuitry, with the lowpass filter under the shield.

I would put a separate metal shield around the 2.45 GHz circuitry, with the 2.45 GHz bandpass under that shield.

If I were going to share the same single antenna, I would then use an additional simple diplexer filter to split the two bands and provide an additional 20 db of channel to channel isolation at the junction.

In other words, if there is any possibility avoid that idea and place those circuits on separate boards (boxed).

868 x 3 = 2604 MHz
So, in principle you don?t have to do anything special.
The harmonics (or the carrier) of the 868 MHz transmitter it will not desensitize the 2.4GHz receiver, if the last one use a decent BPF in the front end.