NetStumbler.com Forums - Post Your Homebrew Antennas = Here

From: Subject: NetStumbler.com Forums - Post Your Homebrew Antennas Here Date: Sat, 6 Jul 2002 22:12:00 -0700 MIME-Version: 1.0 Content-Type: multipart/related; boundary="----=_NextPart_000_0000_01C2253A.26B6CBC0"; type="text/html" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 This is a multi-part message in MIME format. ------=_NextPart_000_0000_01C2253A.26B6CBC0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Content-Location: http://forums.netstumbler.com/showthread.php?s=&threadid=2034&pagenumber=1 NetStumbler.com Forums - Post Your Homebrew Antennas = Here

=20 =20

=20

=20

=20

NetStumbler.com=20 Forums > Wireless=20 Forums > Hardware=20 > Post Your Homebrew Antennas = Here

Pages (3): = [1] 2=20 3=20 =BB=20

=20 Last=20 Thread Next=20 Thread 3D""=20

=20

Author

Thread

lincomatic
UberNetbumbler

Registered: Apr=20 2002
Location: Tanimbar Islands
Posts: = 687

Post Your Homebrew Antennas = Here=20

ok, since=20 measurements of the mobile mark antenna don't seem too = be=20 forthcoming, i decided to take the bull by the horns = and=20 design an omni from scratch. come on everyone, if you = have a=20 homebrew antenna post it here. let's use this thread = for=20 antenna brainstorming.

first, let me make it = clear that=20 i really don't know a damn about RF design. spent = several=20 hours at the library, borders books, and perusing the = web.=20 then i downloaded the EZNEC demo from
http://www.eznec.com/
and = started messing=20 with it.

i still don't have a good grasp of how = to=20 model a real ground plane, but i was able to get some = plots=20 and start tweaking things. i started w/ a quarter wave = whip.=20 In the US, channel 6 is the middle channel at = 2.437GHz. this=20 makes a quarter wave about 30.6mm.
so i started = with this=20 and just experimented w/ various lengths to change the = pattern=20 and SWR and ended up with 89mm. EZNEC shows SWR of = 1.2-1.6=20 over the WiFi band and gain of 4.35dB max assuming a = perfect=20 ground (which we don't have).

so here is my = prototype.=20 it's just a piece of 2mm dia. coat hanger cut to 87mm = and=20 soldered into an N-female panel jack for 89mm length = from the=20 tip to the base of the middle pin on the jack. just = for the=20 hell of it i soldered on the ground plane, which is = the lid of=20 a 3.25" dia. tin can. the tape is just to keep me from = shredding my fingers on the sharp edges.

how = well does=20 it work? i was amazed. walking outside with = ministumbler, i=20 can find my AP 120ft farther away than with the = ORiNOCO built=20 in antenna. inside the house, i went the the place w/ = the=20 worst reception and the signal & SNR went up by = over 10dB=20 vs the built in antenna. i haven't even begun to tweak = the=20 thing yet. not bad for a $4 antenna (the cost of the N = jack).

lincomatic has attached this image:
3D""=20

__________________
~lincomatic

Last edited by=20 lincomatic on 06-02-2002 at 12:37 AM

Report=20 this post to a moderator | IP: Logged

05-29-2002 12:40=20 PM

=20 =

blackwave
Do I look like = I'm=20 joking

Registered: Apr=20 2002
Location: SoCal, OC
Posts: = 1798

Ah, but can=20 you wear it like this? 3D""=20 (See attached)

blackwave has = attached=20 this image:
3D""

__________________
-=3DBW=3D-

Report=20 this post to a moderator | IP: Logged

05-29-2002 01:14=20 PM

=20 =

lincomatic
UberNetbumbler

Registered: Apr=20 2002
Location: Tanimbar Islands
Posts: = 687

i = guess could=20 also feed the tip thru the top of a baseball hat for = war=20 walking and look like a total dork, too 3D""=20

just stumbled w/ it for the first = time on=20 the way to work and it picked up a few AP's i didn't = know=20 existed 3D""=20

__________________
~lincomatic

Report=20 this post to a moderator | IP: Logged

05-29-2002 01:45=20 PM

=20 =

acidrayne
OmniStumbler
3D""=20

Registered: May=20 2002
Location: Kansas
Posts: 405

quote:
Originally posted by lincomatic
i = guess could=20 also feed the tip thru the top of a baseball hat for = war=20 walking and look like a total dork, too

just stumbled w/ it for the = first time on=20 the way to work and it picked up a few AP's i didn't = know=20 existed

I think attaching a propellar to = it and=20 wearing it as a beanie cap would be = nice!!

Didnt=20 someone have a pic similar to this posted at one = point?

__________________
- Rayne

Report=20 this post to a moderator | IP: Logged

05-29-2002 01:48=20 PM

=20 =

blackwave
Do I look like = I'm=20 joking

Registered: Apr=20 2002
Location: SoCal, OC
Posts: = 1798

quote:
Originally posted by acidrayne =

I think=20 attaching a propellar to it and wearing it as a = beanie cap=20 would be nice!!

Didnt someone have a pic = similar to=20 this posted at one point?

Click here 3D""=20

http://forums.netstumbler.com/showthread.php?s=3D&thr= eadid=3D1772&perpage=3D15&highlight=3Dwarwalking&pagenumber=3D= 2

__________________
-=3DBW=3D-

Report=20 this post to a moderator | IP: Logged

05-29-2002 02:00=20 PM

=20 =

sparafina
yatta!

Registered: May=20 2002
Location: AUS/LAX/DCA
Posts: = 133

I = built a=20 similar antenna, but I mounted it on the bottom of a = yogurt=20 cup, cut a slit for the pigtail, glued a speaker = magnet to the=20 inside of the lid and snapped it back on, voila - = instant=20 magnetic mount.

Report=20 this post to a moderator | IP: Logged

05-29-2002 02:06=20 PM

=20 =

lincomatic
UberNetbumbler

Registered: Apr=20 2002
Location: Tanimbar Islands
Posts: = 687

sparafina:=20 post a photo! and tell us what length you chose and=20 why.

acid: haha, that beanie idea isn't a bad = idea for=20 hiding the antenna but the dorkiness of it would = attract too=20 much attention 3D""=20

__________________
~lincomatic

Report=20 this post to a moderator | IP: Logged

05-29-2002 02:35=20 PM

=20 =

acidrayne
OmniStumbler
3D""=20

Registered: May=20 2002
Location: Kansas
Posts: 405

quote:
Originally posted by blackwave =

Click=20 here

http://forums.netstumbler.com/showthread.php?s=3D&thr= eadid=3D1772&perpage=3D15&highlight=3Dwarwalking&pagenumber=3D= 2=20

Thanks for the link BW ... That = is the=20 one I was thinking of.

Linco ... You know the = chicks=20 would dig it.

__________________
- Rayne

Report=20 this post to a moderator | IP: Logged

05-29-2002 02:38=20 PM

=20 =

blackwave
Do I look like = I'm=20 joking

Registered: Apr=20 2002
Location: SoCal, OC
Posts: = 1798

quote:
Originally posted by acidrayne =

Linco ...=20 You know the chicks would dig it.

Oh I can see all those oiled up = bikini=20 silicon filled stumbler groupies lining up now... oh=20 yea...

__________________
-=3DBW=3D-

Report=20 this post to a moderator | IP: Logged

05-29-2002 02:45=20 PM

=20 =

outcast_one
cut/hack/modify
3D""=20

Registered: Apr=20 2002
Location: MA USA
Posts: 25

mobile mark = pics=20

I = was hoping=20 otaku42 would post the pics fairly quickly, but there = seems to=20 be some delay. I will post two of them here, the rest = will=20 appear on his site when he has it finished. These pics = are low=20 res due to the file size limit of the = forum.

outcast_one has attached this image:
3D""=20

Report=20 this post to a moderator | IP: Logged

05-29-2002 07:00=20 PM

=20 =

outcast_one
cut/hack/modify
3D""=20

Registered: Apr=20 2002
Location: MA USA
Posts: 25

second = pic=20

here it=20 is

outcast_one has attached this image:
3D""=20

Report=20 this post to a moderator | IP: Logged

05-29-2002 07:01=20 PM

=20 =

gcrocker
Net = Stumbler

Registered: May=20 2002
Location:
Posts: 32

Not that=20 appropriate for stumbling (it's 20" high and PVC), but = I may=20 mount it on my crappy van for just that = purpose:

http://www.guerrilla.net/reference/antennas/2ghz_collinea= r_omni_lowpwr/

First=20 one I built took 3-4 hours, and I think I can do them = in an=20 hour now.

-glenn

Report=20 this post to a moderator | IP: Logged

05-29-2002 07:17=20 PM

=20 =

sparafina
yatta!

Registered: May=20 2002
Location: AUS/LAX/DCA
Posts: = 133

quote:
Originally posted by lincomatic =
sparafina:=20 post a photo! and tell us what length you chose and = why.

I came up with 73 mm based on a = 5/8 wave=20 whip. Uusing the antenna elmer at http://www.qsl.net/w4sat/five8th.htm, I got=20 178.308/2437. No groundplane, I figure the car would = be=20 sufficient

Sorry no pics on the 5/8 whip, left = the=20 camera at the in-laws. I'll post it later when I = retrieve it=20 from them over the weekend. A pic of the cantenna and = rig are=20 here:

http://forums.netstumbler.com//showthread.php?s=3D&th= readid=3D1823&perpage=3D15&pagenumber=3D2

Used=20 a Bush's bean can; although I found chili and = spaghetti-os=20 cans that were tall enough, they looked too disgusting = to deal=20 with. Used the beans in a lamb cassole, yum. Perhaps = that=20 should be a thread: Cantenna Recipes

Report=20 this post to a moderator | IP: Logged

05-29-2002 08:31=20 PM

=20 =

lullabud
UberStumbler
3D""=20

Registered: Apr=20 2002
Location: CO/CA
Posts: 255

quote:
Originally posted by gcrocker
Not that = appropriate for stumbling (it's 20" high and PVC), = but I may=20 mount it on my crappy van for just that = purpose:

http://www.guerrilla.net/reference/antennas/2ghz_collinea= r_omni_lowpwr/

First=20 one I built took 3-4 hours, and I think I can do = them in an=20 hour now.

-glenn

dude, post photos and design=20 notes!

also, for those who want yet another = tutorial on=20 the pringles can my friend dr. nazo built a nice one = and took=20 photos of the process.

Report=20 this post to a moderator | IP: Logged

05-30-2002 07:06=20 PM

=20 =

sykojester
Net Lurker -=20 phjear
3D""=20

Registered: Apr=20 2002
Location: Tallahassee, FL
Posts: = 135

just looked @=20 the pics (too busy to read everything else right now), = but I=20 know I wouldnt dare go out w/ it the way it looked. I = thought=20 it was nice and all, but man, that looked like a pipe = bomb.=20 LOL. esp all black.

Report=20 this post to a moderator | IP: Logged

05-30-2002 07:12=20 PM

=20 =

blackwave
Do I look like = I'm=20 joking

Registered: Apr=20 2002
Location: SoCal, OC
Posts: = 1798

quote:
Originally posted by sykojester
just = looked @=20 the pics (too busy to read everything else right = now), but I=20 know I wouldnt dare go out w/ it the way it looked. = I=20 thought it was nice and all, but man, that looked = like a=20 pipe bomb. LOL. esp all black.

oh hell, yeah it does... =

Hey has=20 anyone tried using paintball canisters (like the 150 = ball=20 version).. at least you can get those in = clear.

__________________
-=3DBW=3D-

Report=20 this post to a moderator | IP: Logged

05-30-2002 07:21=20 PM

=20 =

lullabud
UberStumbler
3D""=20

Registered: Apr=20 2002
Location: CO/CA
Posts: 255

yeah, it=20 works really well though. the velcro is nice for = wrapping up=20 the cable and holding it in place when you're not = using it. i=20 think it looks nice enough that it doesn't scare = people=20 though. he uses it all the time in coffee shops and = stuff=20 without an overly due amount of funny = looks.

Report=20 this post to a moderator | IP: Logged

05-30-2002 07:23=20 PM

=20 =

blackwave
Do I look like = I'm=20 joking

Registered: Apr=20 2002
Location: SoCal, OC
Posts: = 1798

quote:
Originally posted by blackwave =

oh=20 hell, yeah it does...

Hey has anyone tried = using=20 paintball canisters (like the 150 ball version).. at = least=20 you can get those in clear.

In case you don't know what I am=20 referencing... here is a pic:... and don't mention = what else=20 it looks like.. 3D""=20

blackwave has attached this image:
3D""=20

__________________
-=3DBW=3D-

Report=20 this post to a moderator | IP: Logged

05-30-2002 07:27=20 PM

=20 =

lullabud
UberStumbler
3D""=20

Registered: Apr=20 2002
Location: CO/CA
Posts: 255

get that smut=20 out of here BW!!

Report=20 this post to a moderator | IP: Logged

05-30-2002 07:29=20 PM