RF attenuation due to battery interference problem - RF Cafe Forums

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mjmariveles
 Post subject: RF attenuation due to battery interference problem
Posted: Wed Nov 22, 2006 4:08 am 
 
Lieutenant

Joined: Wed Nov 24, 2004 1:51 am
Posts: 2
Location: Hongkong
Hi All,

I have problem with my 315Mhz SAW based transmitter if the battery is mounted at the backside underneath of the transmitter circuit. It's transmission power will attenuated at large size around -2dBm down to -40dBm.

Do you have any experience on this problem? You know it's quite headache, since I been using many types of battery sheilding material and ferrite beads, filters caps...still doesn't work!

Anybody there please help..thanks!

:shock:

_________________
micky
 
   
 
karthik
 Post subject:
Posted: Wed Nov 22, 2006 9:05 am 
 
Colonel

Joined: Tue Apr 11, 2006 8:13 pm
Posts: 34
Could the battery be heating the SAW and causing a frequency drift? How big is the bandwidth?
 
   
 
karthik
 Post subject:
Posted: Wed Nov 22, 2006 9:06 am 
 
Colonel

Joined: Tue Apr 11, 2006 8:13 pm
Posts: 34
You could quickly cross check the frequency drift due to temperature by operating the transmitter without mounting the battery on the same chassis as the transmitter
 
   
 
mjmariveles
 Post subject: pcb antenna trace
Posted: Thu Nov 23, 2006 1:48 am 
 
Lieutenant

Joined: Wed Nov 24, 2004 1:51 am
Posts: 2
Location: Hongkong
thank you!

i found the problem and was caused by de-tuning the antenna since its very close beneath when a coin battery is mounted. am using a fixed wire type awg#30 monopole antenna.

by the way, i would like to change the antenna to a pcb loop trace type. do you any information about this on how to design? please help. thank you!

:shock:

_________________
micky




Posted  11/12/2012