Internal Laptop Antenna Length

SamL01 · 02-21-2004

Im puzzled, When i installed my new card i connected the two wires that were connected to the original. One was black and one was grey.

The black was main, and the grey was aux.

Curious kinda person that i am, i cracked open my laptop and peeked under the keyboard.

The black antenna for main is very very short, and rigid. While the antenna for aux was long and bendable, it stretched the lengh of the laptop from left to right.

My question is, is it normal for one antenna to be short and rigid while another to be long a flexible?

How is this associated to the connection they are? Meaning aux and main?

fordem · 02-21-2004

Those are the cables that connect the antenna to the card, not the actual antenna, which is usually about 3/4" long.

The location of the antenna varies with the brand and model of laptop. Some manufacturers put them in the LCD plastics, others put them in the base near the hinges or the front edge.

Follow the cable and you will find the antenna - note - this may involve some disassembly.

There are two antennas to allow for diversity reception - in most cases, the main antenna is transmit/receive, whilst the aux is receive only

peekitty · 02-21-2004

Actually Fordem, they probably are a pair of antennae similar to this one in a DLink AP. They are probably different fractions of a wavelength, quarter wave, half wave etc. The other possibility is that SamL01's card is a dual or multi-band model.

Some of the hams on this forum could answer this in better detail, I barely know a whip from a dipole.

SamL01 · 02-21-2004

I took off my keyboard and jerked the cable from the mini pci slot and it infact is it the main antenna.

But what i couldnt get it, was the main antenna was routed underneatth a side speaker and i think it is folded or attached in some way underneathe so i couldnt pull it out.

The aux antenna was in plain site, and very long.

Im not picky, it works so thats important.

I was just curious why such a difference in size.

What if i change the main to aux and aux to main?

fordem · 02-21-2004

Quote:

Originally posted by peekitty
Actually Fordem, they probably are a pair of antennae similar to this one in a DLink AP. They are probably different fractions of a wavelength, quarter wave, half wave etc. The other possibility is that SamL01's card is a dual or multi-band model.

Some of the hams on this forum could answer this in better detail, I barely know a whip from a dipole.

Peekitty

That's actually a dipole - similar to the Aerialix copy that I posted a few days back in the hombrew antenna thread.

I don't think you're going to see those in a laptop - for a couple of different reasons.

Your Dlink AP was probably designed to stand upright so that the antenna is vertical (or close to it). If you put that in a laptop under the keyboard it would be horizontal, which is not optimal and also shielded by both the keyboad and the base, which, in my experience is either metal or plastic with a metallic coating. Some form of shielding is usually necessary to meet FCC part 15 requirements.

You probably could use these dipoles alongside the LCD in the lid, which would be vertical (or close to it) when it's opened, but again in my experience you have the same metal or metallic coated plastic construction.

I'm not saying a dipole can't be used - just that it doesn't seem to be the norm - most of the laptops I've opened with integrated wireless - Dell, HP & IBM - have had patch antennas.

I like your dual band thory though - an 11a antenna would actually be quite short - about half the size of an 11b or g, due to the higher frequency. SamL01 also decribes it as rigid which matches the construction of the dipole using brass tube for one of the elements.

peekitty · 02-21-2004

Yeah, I've seen an assortment of internal antenna layouts also, some cards are cabled to an etched PCB with what I assumed to be a folded dipole design, but perhaps it was a patch. Wouldn't a directional antenna be less than optimal for a mass produced laptop? I can just imagine the helpdesk calls-
Q: "I'm getting lousy reception."
A: "Turn your computer 90° in either direction."
Q: "OK, it works now, but I can't see the screen!"
A: "Ever considered rearranging your office?"

In the AP that was pictured, the internal dipole was at 90° to the external antenna, I believe this would ensure correct polarization with the clients.

fordem · 02-21-2004

Quote:

Originally posted by peekitty
some cards are cabled to an etched PCB with what I assumed to be a folded dipole design, but perhaps it was a patch.

Telex makes this "Flag Yagi" design that contains an etched PCB - there was some discussion in the forum on duplicating it, but I think the actual PCB blank needed turned out to be critical at the frequencies involved

ZipperSeven · 02-22-2004

It sounds to me of what I have seen being used with the internal Dell TrueMobile cards that are dual band.

My Dell is only b/g compatible and I believe has two identical antennas, one mounted vertically in the LCD screen housing and one mounted horizontally (or at leas perpendicular to the screen unit) under the keyboard itself. The thinking of the design, so I've heard, is so the wireless system could maintain a connection regardless of the orientation of the laptop (ie keeping a live connection while carrying the laptop between offices in a wireless environment, etc,) but I'm not an expert.

peekitty · 02-22-2004

Right, a b/g card might have two identical antennae because the b & g specs use the same band - 2.4GHz.

G8tK33per · 02-22-2004

Quote:

Originally posted by ZipperSeven
The thinking of the design, so I've heard, is so the wireless system could maintain a connection regardless of the orientation of the laptop .

Yup, just gotta be careful not to leave the lappy in one place in the small of the chicks back so it doesn't burn...

peekitty · 02-22-2004

You'd be surprised, a lot of the girls I meet are into that...

The Others · 03-01-2004

On the subject of internal antennas, I see some-one is selling them on ebay. It's an interesting read:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...category=44996

Barry · 03-01-2004

Quote:

just gotta be careful not to leave the lappy in one place in the small of the chicks back so it doesn't burn...

Quote:

You'd be surprised, a lot of the girls I meet are into that..

War-doggy??

HITMONEY · 03-02-2004

Quote:

Originally posted by Barry
War-doggy??

War-Pimpin

Barry · 03-02-2004

sweeeet

02-21-2004	#1 (permalink)
SamL01 Registered Member Join Date: Feb 2004 Posts: 8	Internal Laptop Antenna Length Im puzzled, When i installed my new card i connected the two wires that were connected to the original. One was black and one was grey. The black was main, and the grey was aux. Curious kinda person that i am, i cracked open my laptop and peeked under the keyboard. The black antenna for main is very very short, and rigid. While the antenna for aux was long and bendable, it stretched the lengh of the laptop from left to right. My question is, is it normal for one antenna to be short and rigid while another to be long a flexible? How is this associated to the connection they are? Meaning aux and main?

02-21-2004	#2 (permalink)
fordem Tropical Stumbler Join Date: Apr 2002 Posts: 575	Those are the cables that connect the antenna to the card, not the actual antenna, which is usually about 3/4" long. The location of the antenna varies with the brand and model of laptop. Some manufacturers put them in the LCD plastics, others put them in the base near the hinges or the front edge. Follow the cable and you will find the antenna - note - this may involve some disassembly. There are two antennas to allow for diversity reception - in most cases, the main antenna is transmit/receive, whilst the aux is receive only Last edited by fordem : 02-21-2004 at 06:08 AM.

02-22-2004	#11 (permalink)
peekitty Macaca Join Date: Sep 2002 Location: S. Florida Posts: 1,056	Lemme show you my scars... You'd be surprised, a lot of the girls I meet are into that...

03-01-2004	#12 (permalink)
The Others PeaceDriver Join Date: Apr 2002 Location: Dos Palabras, Mandoras Posts: 2,920	On the subject of internal antennas, I see some-one is selling them on ebay. It's an interesting read: http://cgi.ebay.co.uk/ws/eBayISAPI.d...category=44996 __________________ all good ends all ?u=273

03-02-2004	#15 (permalink)
Barry Managing the iTards. Join Date: Dec 2002 Location: Ohio Posts: 5,882	sweeeet __________________ Never do anything you don't want to explain to the paramedics.

02-21-2004	#4 (permalink)
SamL01 Registered Member Join Date: Feb 2004 Posts: 8	I took off my keyboard and jerked the cable from the mini pci slot and it infact is it the main antenna. But what i couldnt get it, was the main antenna was routed underneatth a side speaker and i think it is folded or attached in some way underneathe so i couldnt pull it out. The aux antenna was in plain site, and very long. Im not picky, it works so thats important. I was just curious why such a difference in size. What if i change the main to aux and aux to main?

02-21-2004	#6 (permalink)
peekitty Macaca Join Date: Sep 2002 Location: S. Florida Posts: 1,056	Yeah, I've seen an assortment of internal antenna layouts also, some cards are cabled to an etched PCB with what I assumed to be a folded dipole design, but perhaps it was a patch. Wouldn't a directional antenna be less than optimal for a mass produced laptop? I can just imagine the helpdesk calls- Q: "I'm getting lousy reception." A: "Turn your computer 90° in either direction." Q: "OK, it works now, but I can't see the screen!" A: "Ever considered rearranging your office?" In the AP that was pictured, the internal dipole was at 90° to the external antenna, I believe this would ensure correct polarization with the clients.

02-22-2004	#9 (permalink)
peekitty Macaca Join Date: Sep 2002 Location: S. Florida Posts: 1,056	Right, a b/g card might have two identical antennae because the b & g specs use the same band - 2.4GHz.

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