Can I trim down a wlan internal antenna?

[akremedy]

This looks to be a much more active forum than another I tried to get some feedback on recently...same question, hoping someone here can weigh-in on this before I potentially make a mistake.

I'm installing a mini PCI WLAN card (802.11n/g) and antenna inside of a small form-factor PC. The enclosure is fully shielded with only two small slots in which to mount the tabs at the end of the WLAN internal antennas.

I can easily route the excess antenna cable inside the enclosure, though it would be nice to shorten these to the minimum length.

More importantly, the tabs at the ends of the antenna are too large to fit properly in the slots outside of the shielding meant to receive them.

Is there any functional harm in:
1. shortening the antenna cables - I would guess not as they're inside of an shielded case anyway, and
2. can the tabs at the ends of the cables be trimmed slightly to fit the enclosure better without affecting their ability to properly TX/RX?

Distance isn't much of a factor - as the crow flies, this unit will be less than 10ft from the wireless router.

Thanks in advance,
Adam

For reference, these are the antennae that I'm referring to (pretty standard Tyco wlan antennae):
http://www.pigslipstick.com/uploads/misc/mini_wlan_antennen.jpg

 

[0xDEADBEEF]

I don't know about the design on the picture, if your cables just feed the antenna I guess they can be shorter. If you cut a piece out of the middle though and try to solder things together, you destroy the cable's impedance which causes reflections and heavy losses on the wire.

The cables and connectors are matched to each other, if you mess with the dimensions of the metal parts of the connector or the insulation between them this can break things, messing with the outer insulation shouldn't change anything. If you just shorten the cable and connect it as intended this should be fine, too.

This is all just theory though...

 

[akremedy]

Thanks for the speedy reply! Shortening the lead to the actual antenna is optional - if I were going to this, I'd unsolder the lead at "tab" on the end, cut to length and reattach. Truth is, I'll probably just coil up the excess and choose not to worry about it.

What do you think about trimming down those "tabs" at the ends of the leads? Do you think that altering the area or dimensions will affect attenuation(?). I'm wondering if the tabs are tuned to the 802.11bgn bands at their specific frequencies.

Thanks, Adam

 

[0xDEADBEEF]

Truth is I don't know much about antenna design. Antennas are always tuned, but I don't know how they work in this frequency range. It is quite possible that you could damage them by cutting as it is reasonable to assume that those dimensions are matched to the frequency band. You'd have to find someone who actually knows WLAN specific designs though.

 

[f95toli]

It is difficult to tell from the picture, but those "tabs" could actually be for example patch antennas; and if you start cutting bits out of a patch antenna its properties will change a lot (=it won't work anymore for wifi),

 

[akremedy]

Thanks all, I too fear that altering the ends of the antennae may cripple them. That said, I've got a total of three (for 802.11n) and won't be using more than two (for 802.11g). I'll do some unscientific testing and report back in a week or two.
Thanks again for the input!
Adam