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RF attenuation due to battery interference problem - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.

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

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!



 Post subject:
Posted: Wed Nov 22, 2006 9:05 am 

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?

 Post subject:
Posted: Wed Nov 22, 2006 9:06 am 

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

 Post subject: pcb antenna trace
Posted: Thu Nov 23, 2006 1:48 am 

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!



Posted  11/12/2012
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