Best stubbie external wifi antenna?

I've have 3 different external antennas. But I am wondering if anyone has any recommendations on the stubbiest of the stubbies. Something small that still works very well. I think mine range from 5" to 10" long.

I'm looking for something smaller even without a swivel.

 

www.jimdgray.com has super stubbies... I think they are about 2" long...

 

*Tries to recall knowledge about wavelength*

Wifi (2.45Ghz) has a wavelength of 4.8" so you should get good range from an aerial 2.4" long.

 

I am using a spare D-Link wireless router antenna that is abotu 3" long when folded up. Works just fine with my wi-fi router when I am using this machine over the wireless link. Saves on having a blue snake connecting the two when I'm at home.

Craig.

 

Matthew, does this mean I can somehow trim the oem lid arial to 2.4" and it will work?

 

Some older posts dealt with issues with using the stock antenna for wi-fi
I remember something to do with soldering a jumper wire , to use the antenna properly ?
It’s an old post so if someone here remembers where it was maybe they could put up a link

The antenna length issue is a bit unclear to me as there is ½ wave ¼ wave antenna’s for some communications , so an antenna that’s twice as long might work as well
I'm sure someone here can add to this or clairify

Alex

 

Alex,
Find it here:
http://forum.notebookreview.com/showthread.php?t=215522&page=2
Marconi sent me a very detailed PM on the subject which I will add as an edit to this post later. The Dwagon seems to know a lot about this stuff, but then he seems to know about a lot of stuff!
CAP

 

Yup, Cap'n -

I know I COULD get better matching by sitting down & trimming my OEM CDPD antenna to resonate closer to the 2.4GHZ band instead of the 800-900MHZ band it's designed for; but my performance with the stock stuff was good enuf I didn't care to mess with a good thing. I WOULD love to try a CDMA antenna from a CF-29; I understand they're about 2/3 to 1/2 as long as the one I'm using now and as CDMA is right at 1900MHZ, I think it would hit right at the edge of WiFi's "sweet spot" resonance-wise.

mnem
No, No, No... electrons over THERE, PROTONS on the right...

 

As promised here is Marconi's take on the OEM antennas.

"Basically I use a HP microwave network analyzer., its a kind of fancy swr meter but gives me a graph of the reflected power versus outgoing.
We have one at the TV station I work at so I might aswell use it.
I can tune while observing the graph for the best results, makes things much easier.This works well with the 2 3/4 in ant.
What I do is different attachment points than the original, mostly closer to the stem piece as possible.
On the first ant I did have to add a few chipcaps to tune it down some, no chipcoils, altho I did try the old ones that were used as a harmonic filter. nogo.
but it was passable performance wise , lucky maybe cause it was a mess. Similar to what mnementh did.
The second one worked better without adding anything, I had to remove the coax from the mount and just soldered the coax with very short leads (1/8" long each) directly at the soldertab closet to the ant stem trimmed smaller just enough to solder to.. I also had to find a good ground close to this spot as well, so I cut the flexyboard out completely and used copper foil 1 1/2" long to go from the original ground point to the ground of the coax. basically extending the ground up to the coax where it is now attached closer to the ant. It also acts as a proper groundplane at this freq..
Now we have a Half-wave ant good for about 3dB gain.
I hope all that made some sense. I was gunna post it but hadnt had the time lately as we've been busy with the digital transition,.I take care of the transmitter site too.
If you are brave enough to try it , I'd be interested how it went for you.
I have two more TB's here with ants I plan on turning over soon so I'll be doing those soon as well.

I just got in a long ant and will be trying it soon as well. Altho it'l be tougher and I will have to add series capacitance to tune out the reactance and null the standing wave at 2.4Gig.
The pattern may not be the greatest but it'l be better than nothing too.
As far as internal antennas, Ive been grabbing those flag style ones made for other laptops, and mounting then right under the batt on the screw post at the plastic side. works prettywell for A,B and G wifi.
but nothing beats the look of the external antenna tho.
You are welcome to post any of my reply if you like."

CAP

 

Where have I seen this before?

I musta been asleep when I typed that., hehe.
Just wanted to add, I've tried all kinds of stubby or other external wifi
antenna's, I promptly broke every one of them in normal everyday use.
Even the Sarantel GPS "cow-nub" one's too...
Its hard to find something that will stand-up against abuse.


Thanks for posting this Cap

Chuck

 

I have done Mnem's hack on many of the old RIM antennas with STELLAR results. As good or better than the CF-29 type! All it takes is to unsolder few SMDs and then either use two SMD 000 resistors or, as I do, just solder a jumper where he shows in his post. BAM! Working wifi. Then I usually also mod in the passthrough so it is an easy install as it is all plug and play after the soldering is done. But it does mean that you have to take off the LCD top and the "4 screw" port cover on the bottom as well as removing the keyboard for access.

I can't imagine anyone wanting a better signal than this setup gives.

 

I started out with mnem,s hack of course its very easy to do and will work tons better than the original config as your removing the harmonic filter that gets in the way at 2400mhz.
It did work for me but what prompted me to go farther was the fact I was using the 1/2 watt card and wanted to see the antenna's return loss, and it was really bad, but it could have been just my luck.
I found it worked but I didnt see much difference with the antenna extended or retracted , maybe 3db. I figured it must be going out the lcd instead or a mis-match, or bad/pinched cable. so thats why I did it a bit different, of course YMMV.
My second attempt worked much better.
What really worked the best was to add the rp-sma connector to the rear and use either an omni or a bi-quad antenna.
I've even connected to a 10' dish that was up 660' up a tower out 30 miles from town and was able to connect to home, but had interference issues from others in town. talk about making netstumbler go crazy

So basically, all I did was solder my connections much closer to the stem and ground , bypassing any residual inductance that added in from the board and 00 ohm resistors.

Chuck

 

I should add that this works the best on the shorter RIM antenna's, the longer one's really need the reactance tuned out and even then they will have a very narrow vertical beamwidth. so they will have to be perfectly in the vertical position to use it when far-out from the access point.
Up close it wont matter much, but the higher gain may become a health issue if using a high power card.

Chuck

 

You see, this is what I WANTED to tinker with, but simply didn't have the proper equipment.

Chuck, did you see my trial & error attempts posted here:

http://forum.notebookreview.com/showthread.php?t=215522&page=2

and the resultant "seat of my pants" results posted along with?

I tried removing the poly PCB and soldering my antenna lead directly as you suggested - it decreased my reported signal level by more than 5dB at everything from 100' and out; that's why I went back to using a single 0 ohm SMD as a bridge.

I suspect the differences we report are due to the differences in our basic setup; you started out with the CDMA antenna and I was using the analog Cellular antenna; plus I suspect you may have replaced the entire antenna cable back to the WiFi card. I did not; I re-used the existing semi-rigid cable and simply fabbed an adapter so I could retain the functionality of the RF dock connector at the back of my laptop. Of course, all this adds parasitic loss which changes the resonance of the circuit, which may have been why my setup works so well with an obviously mismatched antenna.

Do you suppose that between the metal case and the cabling tomfoolery, I accidentally stumbled across a setup that's resonating at 5/8 wave or full-wave instead of half-wave? With the ground plane provided by the metal chassis, I can see it acting as a dipole instead of a monopole...

mnem
Dipoles? Monopoles? Sounds kinky...

 

Yes, I do believe that there is more to this as each time I've done this , its been a different result each time, of course some of this could be due to a slightly different length in the cable. This is microwave and any mis-match in the antenna will look different to the radio
or analyzer with small changes in cable length , maybe you lucked out and yours is acting as a transformer for that and tuned out the reactance too.

Yes, I did read your results and I commend you with that great job you did.,
You did beat me to doing it., hehe. I did copy you the first time around, thanks.

As we get away from the easy to match 1/4 wave it gets tough to try to tune these longer antenna's., without a matching network at the base of the antenna we are basically doing it with coax. kinda a poor way but sometimes it works great.
I guess my next attempt, I will have to try to find the correct length and post it here.
Hopefully using the factory cable. its 50ohm. but if its changed to a different diameter or manu it'l have different parasitic capacitance changing its length some.

Hey, watch what your doing with that pole ..son

 

Yeah, I saw that you posted while I was posting my questions - LOL. Thanks for the props - I do believe that since you do this for a living, your WiFu is a bit stronger than mine. Also, since I was only messing with the 100mw & 400mw Atheros cards, I'm sure I get a bit more leniency in the reflected wave. I'd be curious to see what the actual numbers with my complete setup might look like; but I'll probably be ashamed.

I really was surprised at Panasonic's take on the overall antenna design; there really is a HUGE mass of metal there given the frequencies we're operating at; lots of opportunity for parasitic loss. That slip ring is flippin' HUGE!

mnem
BoingyBoingyBoingy...

 

What is a bi-quad antenna? Do you have an example? Thx. Scott

 

Sure thing http://martybugs.net/wireless/biquad/

As you can see if your handy with some simple tools and can find the connectors ok,
You can build it pretty easy and you wont have to tune it.
It has some pretty good gain for those hard to reach areas

Chuck

 

While this might not fit on your stubby, theres this:
http://www.instructables.com/id/DIY-WIFI-Antenna-Reception-Booster/

I like the stubby antenna's that Jim Gray has here:
http://www.jdgastore.com/index.php?act=viewCat&catId=65

 

Thanks for the links. Just following some of the discussions on the links is interesting. I've got a few ideas now.

 

These are cheap and work for other thoughts:
http://cgi.ebay.com/Apple-short-laptop-wireless-wifi-U-fl-bluetooth-antenna_W0QQitemZ320351992981QQcmdZViewItemQQptZPCA_Cables_Adapters?hash=item320351992981&_trksid=p3286.c0.m14&_trkparms=66%3A2|65%3A1|39%3A1|240%3A1318