Help needed with an increase in noise floor

I am hoping to get some help with an issue I am currently having on a new design I am working. The design incorporates the following:

434 MHZ Transceiver
WIFI module
switching power supply
other components.
The issue I have is as follows:

(1) The noise floor I measure on the RRSI line of the receiver is around 450 mv without the WIFI module on.
(2) When I use a chip antenna on the WIFI module the noise increases about 20 mv during WIFI transmission (acceptable)
(3) When I use a patch antenna (cnnected with small coax cable) the RRSI level increases to about 550 to 600 mv (about a 6 dB increase in the noise floor)

My main question is how to reduce the noise floor on the reciever when I use the patch antenna for WIFI and why is it occuring with only using a coax cable.?
The product is mounted inside a small plastic enclousre.

Robert Patterson
Any help appreciated
[email address deleted]
.

use low NF active component is one of the way...

So basically use an LNA on the input then with maybe a saw filter?
Question is why a patch antenna connect to the WIFI module with a coax cable increases the noise floor on the 434 MHZ Receiver?

Hi,
first question : why your 434 MHz is shared with the Wifi module ?
if you use two different antennas, they prebably don't have the same bandpass. So in one case the noise is more important than the other.

The 434MHZ has a seperate antenna from the WIFI module. I think I found the issue though.
My grounds were split to much. I had little ground under the WIFI module and noticed when the WIFI module was activated the noise floor on the 434 MHZ reciever increased. The actual ground on the 434 circuit increased as well.
There appears to be a potential difference between the grounds when WIFI turns on which may be increasing the noise floor. Does this make sense?

It 's difficult to say without seeing your PCB. Perhaps you have got some coupling on your card...