diy aeriel for wireless router

[Tim W]

Family complaining about poor internet wireless reception around the castle. A quick search and I see the first thing to try before boosters and repeaters is simply a bigger aerial on the router (currently 3" long) at a cost of around £20. Being a tight wad I thought I might test a home made aerial first - an aerial is just a length of metal I think - and am considering how to do it.

Am I right in thinking I can leave the insulation on a length of copper wire and use that? Will the length I cut it at make a difference? I mean obviously it will be longer, maybe 30" instead of 3" but does it have to be a multiple of a wavelength or something? I am guessing the aerial can be thin - a coat hanger not necessary here - but is solid copper better than strands?

Tim W

[Dave Liquorice]

Yes.

Yes, critical.

Yes, but it's not quite that simple.

Connecting it to the router with low enough loss coax and the small connectors will be the tricky bit. Far less bother to move the wireless AP to a better location. What it's built into the same box as the ADSL modem and that can't be moved easily. Bit stupid rarerly is the best place for the ADSL modem the best place for a wireless AP.

The wireless AP needs to be located away from things as much as possible, stuffed down the back of a desk surrounded by monitors and PC's is not, erm, ideal. You can buy aerials and TBH that is probably the better choice as it should come with suitable cable and connectors etc.

[Andy Burns]

Sometimes with embedded voodo, the ones embedded within laptop screens especially so.

Usually 1/4 or 1/2 wavelength, but that'll be what you already have

I am guessing the aerial can be

What's the velocity factor of a coathanger?

If you want to make existing access point more directional, you could try this

[robgraham]

house and having been in electronics, though not RF, can at least do all the making part.

I read through the links and was rewarded at least in understanding why a coat hanger might have a velocity factor :>) - no doubt this factor was mentioned in my training all too many years ago now.

Two questions - why does the designer of the aerial on the FPV forum not take the velocity factor into account, and why does it only apply to the 'folded' back section - I can't see that the 'bazooka' configuration is any different electrically?

Rob

[Derek G.]

?? Thin implies sharply tuned. It's unlikely to be anything like right.

For a Yagi type beam think in terms of elements at least the diameter of a pencil. Microbore copper tubing would spring to mind.

I do possess a comercially made beam. If anybody wants the dimensions email me.

Derek G.

- but is solid copper better than

[mick]

A bigger aerial doesn't help on a transmitter, only on a receiver. That makes it useless on a wireless router. The electrical length of the aerial is fairly critical to it's performance (and isn't usually the same as the mechanical length!). Also, many router aerials are actually a solid or flexible core with the aerial wire wound around it. The whole thing is then covered with insulation. If you want to try a mod then go ahead, but I doubt very much if it will make things better - probably much worse so make sure that your mod is easily reversible! As the original is almost certainly tuned to 1/4 wavelength you could try something exactly twice the length to make it 1/2 wave or even work out a length for 5/8 wavelength (which is probably better than either but not legal as it has gain).

The very best way to get more range is to move the unit to a central location in the house. If that doesn't work very well for keeping the ADSL lead short then you could add a separate non-wireless ADSL router and connect it to the wireless one using CAT5, effectively putting them on their own wired network.

[tony sayer]

you have. Unless you want to improve the range of this existing system in -One- direction i.e. focusing the power you have rather than broadcasting it then any additional aerial you add onto the existing ones isn't likely to make it any better..

BTW .. Aeriel is spelt Aerial ;!...

[tony sayer]

The velocity factor is the slowing of a Radio frequency signal in a metal as In metals they travel slower than free space...

Its all there on goggle...

[tony sayer]

In article , Derek G. scribeth thus

Diameter of the radiating elements has a function on bandwidth..

Useful stuff..

Not in this instance at those frequencies .. conduction is on the surface of the metal, look up "skin effect"...

[robgraham]

Yep, Tony - been to Google and read that. Google might answer my exact questions if I could find the right search terms but then that doesn't help anyone else. It's the exact questions that require the answer.

Rob

[Dave Liquorice]

A wireless router also recieves how else does it provide a bidirectional link?

[Terry Casey]

If, as Tony says, you can live with a uni-directional aerial - depends, of course, on the location of all receivers wrt to the transmitter - the corner director in Andy's link should do the trick and costs virtually nothing.

Forget about velocity factors and coat hangers - anything you come up with will be worse than you've already got, unless you built a well designed multi element directional aerial at considerable expense ...

Note the important words there: 'well designed' 'directional' 'expense' and compare with about fourpence for the much better corner reflector with proven performance ...

Otherwise follow Tony's advice ...

[John Rumm]

"Bigger" aerials start at about a fiver for a rubber duck type:

remember that aerial gain is in effect at the expense of omni directionality - i.e. higher gains result from more directionality. So depending on the layout of the kit you can end up making matters worse rather than better (at least for some users).

Indeed - although consider you are dealing with frequencies at 2.4GHz and up, so piping signals down wires is not an easy thing to do over long distances. Careful use of appropriate connectors and cables etc is a basic requirement.

Probably, but its not going to make that much difference.

In reality, the sighting of the AP itself is one of the critical factors. Glued into the same box as the router alas does not always allow for the most flexibility.

[dennis]

The velocity factor affects the length required to be a wavelength. It affects the matching, etc and hence the performance at the required frequency. E.g. a quarter wave isn't the same in free air as it is in coax or on a yagi for the same frequency.

I would move the router about before touching the aerials. A move of a few inches can make a big difference.

[fred]

In article , Tim W writes

Add a wireless access point at the opposite end/level of the house, they're a tenner. The optimum 1/4 wavelength aerial for 2.4G is 3cm so you prob have the optimum(ish). I think you've said you had put signal conduits in at your place so cable to the access point should be trivial. Prob a good idea to have the kids on wireless as they always use too much bandwidth anyway ;-).

I assume you've only put celotex round the outside otherwise you'll be trying to blap the RF through foil.

Use netstumbler to check for other wifi sources on the same channel and check the various wikis for channel spread info.

[Tim W]

Thanks for replies.

We won't mess with the aerial for the minute. We will start with a tinfoil reflector on the router aerial. Then a colander/seive dish on the usb dongle thing on the PC upstairs. Kids won't thank me for that, they want technology that costs money.

Tim w

[hugh]

In message , mick writes

Don't transmitters have antennae?

[tony sayer]

So what exactly do you want to know then?...

[The Natural Philosopher]

course the do, and that's why they put a couple of inches on Droitwich instead of the 200 meter tall towers and ground planes they thought they needed before mick told them they had been wasting their time for 60 years.

[Tim W]

And reporting that they both make a significant difference. Problem solved.Cost nil

Tim W