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ikarus1
Premium
join:2002-10-23
Urbanna, VA

reply to Just Looking9

Re: These Ducks Quack !!!

said by Just Looking9:
Hey, way cool pic, ikarus. Where'd you get it??
-johnmdesmond
A gentleman named John Desmond mailed it to me. I'll put it on the site next week. He and I have been emailing each other for a few days. I don't know much about him, but he clearly understands optics and photography. He got it by putting a "slave flash down the hall behind a cardboard with a couple of slits in it."

It was so interesting, I've been in the garage all evening with a couple of laser pointers and some templates. It looks like all the templates pass muster -- BUT -- it is a whole lot harder to make a *REALLY* good one than I thought.

I'll be looking at simplification, with an eye towards improved accuracy in implementation because that focal point is *REALLY* important and it is too easy to miss it by a quarter of an inch.

You ... well... I did not read the sig till I posted.

-m-
--
»osiris.urbanna.net

[text was edited by author 2003-03-09 00:47:39]

Just Looking9

join:2002-02-09
Alexandria, VA

Mike: "Oh, a wise guy, ehh?"
John: "Nyuk, nyuk, nyuk *bonk* OWW!"

I just wish the implementation were up to the quality of the pix. My line of sight between the two (single-antenna) DWL-900AP+'s passes through one floor, one hallway wall, and two room walls at a 3D oblique angle (maybe about 5'x6'x15'). Resulting data rates:

1. with reflector - 2.02 Mb/s (megabit per second)
2. without reflector - 2.13 Mb/s
3. reflector backwards - 2.06 Mb/s
4. removed antenna - 1.74 Mb/s

Evidently, the situation has so much multipath, I'd be better off just walking around with a field strength meter to find a good site. (I guess this is what they mean by "hot-spot"!)

At one point I removed the antenna and covered the DWL with the dog's stainless steel waterdish. The whole thing was sitting on top of my steel-case computer with just path to air under both sides of the dish. I was still able to stream audio!

IIRC, the DWL actually does have a second internal antenna for diversity. It may have been ignoring my beautiful parabola at some points in the experiment.

-John

said by ikarus1:
said by Just Looking9:
Hey, way cool pic, ikarus. Where'd you get it??
-johnmdesmond
A gentleman named ...
...
You ... well... I did not read the sig till I posted.

-m-
--
»osiris.urbanna.net

[text was edited by author 2003-03-09 00:47:39]



netwire
Premium
join:2001-04-27
Shelby, NC
kudos:1
reply to boomerbubba
Where can I buy one of the "these ducks quack" things as pictured in the first post? I know there is a site that sales them but cant find the link...
--
I can't wait for my local McD's to have a Wireless Access Point!

marlinw

join:2003-02-04
Denver, CO
Why not follow the links in earlier posts. There are instructions and templates. Build your own and save a bundle. I built mine out of styrofoam and stainless steel screen I had laying around. Spent an hour making it and another hour making it pretty. AND it cost like maybe $2 to build.


boomerbubba

join:2001-06-15
Austin, TX
reply to netwire
said by netwire:
Where can I buy one of the "these ducks quack" things as pictured in the first post? I know there is a site that sales them but cant find the link...

You don't buy them. You just follow instructions and build them.

»www.freeantennas.com/
--
A good lock will keep an honest man out.

latichever

join:2000-06-09
New Haven, CT
reply to Just Looking9
Anybody have real world experience with the parabolic antenna and 802.11a equipment? I have a Netgear HR314 router/access point. Love the throughput. Am disatisfied with the range. Would like to get consistent coverage on the second floor--AP on first floor where everything is fine--and get some coverage on the third floor.

Got a four pack of Pringles at the local BJs Warehouse with a dollar off coupon.

IMHO the key design issue is getting the cardboard or whatever is used to hold the parabolic reflector's shape and through which the dipole goes through. I've looked at all the pictures and am wondering if a thick piece of styrofoam could do this job. Anybody have any tips on this issue? Thanks in advance.

Am trying to avoid shooting up wires to the second and third floor of my house and/or not having to buy additional access points. Netgear is having a 50 dollar off rebate deal on their APs that expires 3-31, so I'm going to have build this and try it out before then.


boomerbubba

join:2001-06-15
Austin, TX
The parabolic design should work on the 5 Ghz frequencies without modification. Be aware that these frequencies are inherently more susceptible to attenuation in walls, etc., than 802.11b.

The dissected pringles cans should work fine, I think, with styrofoam. But if it were me, I would look first to the EZ-12 template on the FreeAntennas.com site. I haven't built it, but it really does look easy.

latichever

join:2000-06-09
New Haven, CT

reply to boomerbubba
Boomerbubba,

Thanks for the link to the ez-12. Somehow I missed that. I think I'll try it first.

A couple of questions though:

The designer of the antenna talks about the importance of the reflector being a square. The ez-12 template is a rectangle--unless I missed something else.

And, what kind of glue works to attach foil to card stock? Elmers or something like that?

Thanks again.
[text was edited by author 2003-03-25 08:13:47]


boomerbubba

join:2001-06-15
Austin, TX
said by latichever:
The designer of the antenna talks about the importance of the reflector being a square. The ez-12 template is a rectangle--unless I missed something else.
I believe it is just a case of two different designs. There is no magic requirement for the square dimensions of the first design; it is just that the published calculations assume those values.
said by latichever:

And, what kind of glue works to attach foil to card stock? Elmers or something like that?

I believe Ikarus recommends airplane glue.
--
A good lock will keep an honest man out.

kornell

join:2003-03-24
Markham, ON
reply to boomerbubba
Where should the center of the reflector be relative to the dipole antenna (on a WAP-11)? From post #1 in this topic it's not clear since those foam blocks are so large!

Oh, one more thing... I have my WAP-11 up to 0x90 on the power setting for every channel (I read somewhere it was better than 0x80 I think), but if I put the reflector on (new) 5dBi rubber ducks should I reduce the power to maximize range?

k


Thrawn2
Grand Admiral Thrawn
Premium
join:2001-04-09
Davenport, IA
reply to boomerbubba
WOW. those things accuatly help. HAHAH thats funny if i didnt already have 100/100 3 floors away. i would try it.
--
If i had the money i would do COKE.


rjackson
Premium,VIP,MVM,Ex-Mod 2005-13
join:2002-04-02
Ringgold, GA
kudos:1
reply to boomerbubba
Click for full size
Well here's mine, completely inspired by reading this thread. I made them out of a couple of cans of Cheez Curls, held together with cardboard and duct tape. I used this template, so thank you M. Erskin and everyone else.

As you can see from the pics, I get a marginally better signal with the ducks installed. I don't understand any of the formulas or anything, I just traced the arc and punched a hole at the focal point.

Usually, I am sitting within 30ft or so of my AP, so these things weren't an absolute necessity, I just thought they'd be cool to build. And so easy, too. The hardest part was eating all the Cheez Curls first *burp*
--
quidquid latine dictum sit altum viditur