Extending bluetooth antenna

[vinodstanur]

Hi, I am keeping a bluetooth module inside a closed metal enclosure. I am not getting proper range because the pcb trace antenna is enclosed with metal. How can I take out the antenna? I am sure that simply soldering out a wire from the tip of pcb antenna is not a good solution.
Should I use any coaxial wire to take out the antenna connections from the bluetooth module and then connect any 30mm thick wire as antenna? (or some thing like that)

 

[davenn]

you really need to move the antenna to the outside of the case. its never going to work properly mounted inside.
I repair on Yuma Tablets and they are also a metal case. The BT antenna which is etched on PCB is mounted on the outside
with a short length of coax connecting it to the BT module


Dave

 

[vinodstanur]

In my case, I can take the antenna out using a thin coaxial wire, but still the antenna cannot be exposed in air, instead it will be still totally covered by our body, say I was pressing the bluetooth antenna and the complete system using my hand so that the antenna cannot be exposed...
IN such case what can I do to get the maximum RF strength?

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Can any one suggest a good antenna?

 

[E Kafeman]

A BT antenna that is totally covered by body or hand will be very ineffective due to that tissues absorbs radiation. There is no antenna shape that could change amount of absorbation caused by human body. Another related problem is that an antenna totally covered by body will have its impedance detuned, which also cost performance, if it not is compensated for.

 

[biff44]

yes, unless your metal box is poorly constructed with bit gaps or cracks at the cover...it will not radiate.

If you are constantly in contact with the outer portion, you could design an antenna that is roughly tuned to frequency when held tightly. It helps if the antenna is surrounded with a thicker insulator than normal, some sort of foam sheath

Coax can be connected from where the base of the printed antenna was. of course u need to disconnect the printed antenna, a cut across the trace with an Xacto knife will do. YOu need a good ground plane connection to the coaxial cable shield--hopefully the board has a ground plane on it, some don't