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Blueteeth antenna short transfer distance

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James_Zheng

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Hi all,

Currently, I got a problem of Blueteeth antenna short transfer distance issue, the spectrum analyzer shows it could get right frequency band (2.4-2.5G), I try to exchange different type of Balun, no improvement. However, when I use a wire instead of antenna, it improve large. who could give me some advice about it? Thanks a lot.

Best Regards
 

what kind of antenna ru using?
Did u take care of impedance matching?
Even if u replace balun if impedance is not matched max power will not be radiated out.
It might be that with wire antenna impedance is matched....
Moreover, wire antenna will be at a height from the ground which gives more range...
 

Hi dharanklhar, Thanks a lot for your response. The antenna is Ceramic Antenna 2450AT18A100E, the Balun and antenna impedence is 50ohm, do you think we also need to redesign matching net?
BTW, there is no GND under Antenna, so do you think the GND will impact wire antenna performance? The wire I select is 3cm.
THanks a lot.
 

For a ceramic chip antenna ground plane should not be there under antenna....
For wire antenna, if ur using co-ax, u need to solder outer braid to ground plane...
Wire length is ok, i think u have calculated using c=fl

As you said, if it is matched to 50ohm, I think ur ceramic chip antenna is having less gain... this may only be the reason you are not getting range....
 
There is impossible for a very small antenna (3.6mm x 1.3mm x 0.5mm) to work like a quarter wavelength antenna (~3cm in your case).
Whatever specification the chip antenna manufacturer mentioned, a piece of wire will work better.
 
Thanks for your help. how could I improve chip antenna peformance? do you have any suggestion? Thanks.
 

You need a network analyzer for impedance matching, not spectrum analyzer. For a small chip antenna is resulting antenna performance very depending on ground plane impedance as it actually is 50% of the antenna (a monopole part of the dipole). If the ground plane is small or very lossy can impedance measurement be tricky as measurement probes adds to ground plane size. Isolation of the probe coax with ferrite can help. From manufacture given mounting recommendation and performance data is almost always assumed for a non lossy ground plane with size lambda/4 or bigger. If it is a body worn equipment must also this impedance be taken in account.
 
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