NetStumbler.com Forums - Post Your Homebrew Antennas = Here

From: Subject: NetStumbler.com Forums - Post Your Homebrew Antennas Here Date: Sat, 6 Jul 2002 22:12:19 -0700 MIME-Version: 1.0 Content-Type: multipart/related; boundary="----=_NextPart_000_006B_01C2253A.31EE0AD0"; type="text/html" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 This is a multi-part message in MIME format. ------=_NextPart_000_006B_01C2253A.31EE0AD0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Content-Location: http://forums.netstumbler.com/showthread.php?s=&threadid=2034&perpage=40&pagenumber=2 NetStumbler.com Forums - Post Your Homebrew Antennas = Here

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

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Author

Thread

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

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

quote:
Originally posted by lullabud =
ironically=20 though, the pringles can isn't metal and = hence=20 doesn't work the way you'd expect that design to = work. the=20 cantenna page has more details on it. i think that's = why the=20 pringles works well directionally as better than the = internal card antennas omni... did that make sense? =

I also understood that it was not = required for the casing to be metal in substance, so I = opted=20 for plastic...

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05-31-2002 01:37=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 ZipperSeven =
Blackwave: I=20 actually think that the link you have was the link = that=20 inspired us to build the pringles can. As to=20 the...hmmmm....'dildo-tenna', seems like it could = work, but=20 it's not a waveguide with no outer metal shell, and = so=20 diameter doesn't matter (as long as the element is = centered=20 correctly). The key pieces in the pringles cantenna = are the=20 internal structure, as g0tr00t's pimp tight picture = shows.=20

I believe I have read otherwise = on the=20 theory behind these cantenna's... I thought I read = that a=20 casing of metal was not necessary for these since it = was based=20 on the internals, their construct, shape, spacing = etc.. the=20 pringles can does not allow for the ideal mechanics of = the=20 wavelength... and so I thought perhaps something = similar but=20 larger may.

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05-31-2002 01:39=20 PM

=20 =

lincomatic
UberNetbumbler

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

check out the=20 kool stamp yagi here:

http://seattlewireless.net/index.cgi/DirectionalYagi#line= 7

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05-31-2002 06:58=20 PM

=20 =

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

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

Antenna = pics=20

The pictures=20 I posted of the Mobile Mark are very close in quality = to the=20 original 640x480 pics. The antenna does not photograph = too=20 well because it is reflective, and my crappy kodak = camera will=20 not focus well up close. I will be buying a better = camera=20 soon, I may photograph the Mobile mark again with the = new one.=20

The "pringles can" antenna is the last one I = would try=20 to build. It is the poorest example of a "yagi" that = people=20 build. Everything about its design is wrong. A simple = coffee=20 can antenna will outperform it, and is far easier to = build.=20 You could also try to build a copy of the Comtelco = antenna.=20 This antenna works well mounted on the rear view = mirror facing=20 forward, or aiming out a side window. Link is = below.

http://devices.planet-wireless.de/comtelco/index.html=

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05-31-2002 07:36=20 PM

=20 =

lincomatic
UberNetbumbler

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

outcast_one,
thanks. i've already buillt = the=20 comtelco one thanks to u and otaku42 (see his page = comtelco=20 page at the bottom). 3D""=20
i also have a cantenna but both of = these antennas=20 are too directional for stumbling. that's why i'm = looking for=20 an omni design. the antenna i posted at the beginning = of this=20 thread is working pretty well but i just want = something to=20 compare it against.

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05-31-2002 07:39=20 PM

=20 =

ZenOps
Mini = Stumbler

Registered: May=20 2002
Location:
Posts: 7

Although I'm=20 a newbie (and just learning about how to make good = antenna's)=20 I'd thought I'd mention this, since people seem to = really like=20 the magnetic mount.

The strongest magnets ever=20 manufactured, are inside of harddrives. I have broken = apart=20 many dead harddrives *just* to get the arm magnets. = Great=20 thing about them is that they are usually solidly = attached to=20 a well shielded piece of solid metal with holes in it = for easy=20 mounting of whatever you might want to attach to=20 it.

Last edited by=20 ZenOps on 05-31-2002 at 08:15 PM

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05-31-2002 08:03=20 PM

=20 =

lincomatic
UberNetbumbler

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

interesting=20 idea. now i have a use for some of those old junk = drives old loudspeakers also have good strong = magnets. a=20 good source is those old rotted out speakers in the = back of=20 your car.

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05-31-2002 08:39=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 ZenOps
The = strongest=20 magnets ever manufactured, are inside of harddrives. =

I am sure... though I have = noticed while=20 destroying 7 hard-drives and collecting the magnets = that they=20 break rather easily... they are not tempered to = withstand too=20 much impact.. though if you try this at home readers, = to watch=20 out where your fingers are then they get stuck = together=20 because they can pinch pretty hard when snapping=20 together.

Also I have noticed at some hardware=20 swapmeets people try to sell these ex-hardrive magnets = from=20 the drives and do little "magic" tricks with=20 them...

btw, welcome ZenOps.

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05-31-2002 09:00=20 PM

=20 =

sparafina
yatta!

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

The=20 get-off-grid/alt energy folks suggest using magets = from the=20 magnetron in microwaves for their homebuilt = generators. Never=20 tried it, but I've been cruising around looking for a = dead=20 microwave on the curb. Stumbling meshes with my other = hobby of=20 dumpster diving/curbside crawl. Gawd I love free=20 crap.

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05-31-2002 10:44=20 PM

=20 =

ZipperSeven
Write that=20 down.
3D""=20

Registered: Apr=20 2002
Location: Tallahassee, FL
Posts: = 127

Geez, and we=20 just threw out an old microwave. I had considered = pulling it=20 apart to salvage parts from it, but it was at the curb = and=20 picked up before I thought about.

Yes, the yagi = design=20 doesn't have to be metal. The inner lining of the = pringles can=20 has so little metal content in the lining that it = actually=20 does nothing. The important metal part is the bottom = plate,=20 which becomes a reflector. It is the waveguide = antenna=20 that needs to be all metal, those are the coffee can = and my=20 pirouline cantennas. Those have no internal structure. = I mean,=20 you put a hole in a can, how hard can that be? I've = been=20 looking for a good omni design to build, and so I too = am=20 itching for good specs on the mobile mark and fab-corp = omni=20 antennas, as well as planning to build a clone of the=20 lincomatic/otaku/outcast_one type.

__________________
Waiting for 200 to = change my=20 avatar!

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05-31-2002 11:41=20 PM

=20 =

lincomatic
UberNetbumbler

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

zipper,
i=20 think yr right about the yagis...just about every = other yagi=20 i've seen is housed in a pvc pipe...flickenger himself = said he=20 knew jack about antenna design...

btw, the = mobile mark=20 IS the fab corp antenna.

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06-01-2002 12:12=20 AM

=20 =

ZipperSeven
Write that=20 down.
3D""=20

Registered: Apr=20 2002
Location: Tallahassee, FL
Posts: = 127

Huh, who=20 actually builds them then? I thought they l00ked=20 alike.

__________________
Waiting for 200 to = change my=20 avatar!

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06-01-2002 12:27=20 AM

=20 =

lincomatic
UberNetbumbler

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

fabcorp is=20 just a reseller. remember they are a tiny op...how = could they=20 build all that stuff?

they are only $38 in = quantity=20 >1...i am almost tempted to get one to try out if i = can get=20 someone to buy the 2nd one...
i don't have any = commercial=20 antennas to compare my homebrews to. something tells = me that=20 it won't be much better than a homebrew though. that's = why i=20 wanted to build one. but now i'm pretty sure we'll = never be=20 able to get exact enuf measurements to build one = unless=20 someone is willing to put their calipers to = one.
just a few=20 mm off and yr SWR can go thru the roof from what i've = seen w/=20 EZNEC.

wish i could org a local antenna = shootout to see=20 how good my stuff really stacks up against the = overpriced=20 commercial stuff.

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06-01-2002 12:33=20 AM

=20 =

sparafina
yatta!

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

quote:
Originally posted by ZipperSeven =
planning to=20 build a clone of the lincomatic/otaku/outcast_one = type.

I started building one today, so = I made a=20 template in visio, here it is in .gif. Not sure how = folks are=20 printing it so measure twice, cut once, yatta, = yatta

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

Last edited by=20 sparafina on 06-01-2002 at 08:10 PM

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06-01-2002 08:07=20 PM

=20 =

lincomatic
UberNetbumbler

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

quote:
Originally posted by ZipperSeven =

My next=20 project is to build a patch antenna, based on the = patch=20 design which floated around here recently (perhaps = sage of=20 sages blackwave will know exactly which link I mean) = which=20 was built in a tupperware sandwich container.

btw, though you can't tell from = the pix,=20 it's actually considerably smaller than a sandwich = container.=20 that's one thing i like about this antenna. it's nice = and=20 compact.

if you build it, i also recommend that = you=20 support the patch on all 4 corners...the spacing will = be a lot=20 more accurate.

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06-01-2002 10:15=20 PM

=20 =

ZipperSeven
Write that=20 down.
3D""=20

Registered: Apr=20 2002
Location: Tallahassee, FL
Posts: = 127

What diameter=20 are you guys using for the bottom panel? I guess that = really=20 determines the size of the container that it's mounted = in.=20

Lincomatic: I think I have just the solution = for=20 spacing the plates: I have these little rubber pieces = with=20 adhesive backings, the kind you stick to stuff to keep = it from=20 scratching the surface you put it on. They can be = trimmed to=20 the perfect height, I believe. I'll let yous guys=20 know.

Sparafina: Thanx for the template. I = think I can=20 actually scrounge up a piece of brass that I can cut = both=20 from.

Also: do you guys think that there could = be a=20 negative impact by using copper instead of brass? My = sister=20 uses copper plates that are probably the right gauge = for her=20 art projects. I could grab one of those = instead.

__________________
Waiting for 200 to = change my=20 avatar!

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06-02-2002 12:11=20 AM

=20 =

lincomatic
UberNetbumbler

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

copper is a=20 better conductor, so isn't it better than brass?
i = made=20 mine out of steel. would be interesting to see the = diff i in=20 performance w/ different metals.

otaku42's page = says=20 90mm for the ground plane. i cut mine a little smaller = to fit=20 in the container by squaring off 2 edges (the = container was=20 rectangular). here's otaku42's link again.

let = us know=20 how the rubber spacers work. sounds like a good=20 sol'n.

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06-02-2002 12:25=20 AM

=20 =

lincomatic
UberNetbumbler

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

just did more=20 EZNEC analysis of the omni whips. i just don't get why = 5/8wave=20 is supposed to be good. 5/8 wave (76.875mm) has SWR of = 7->5.1 over the band and max gain 2.95dB @ 15deg = elevation.=20 my 89mm has SWR 1.1->1.7 and max 4.32dB @ 45deg. @ = 15deg=20 it's only 0.86dB, though. doesn't the high SWR just = kill the=20 5/8wave anyway?

any hams out there? maybe the = prob is i=20 just really don't know what the heck i'm doing w/ = EZNEC. but i=20 don't have a spare N jack to test w/ the 5/8wave at = the=20 moment.

been stumbling more w/ the whip and it = kicks my=20 patch...i've found several AP's i didn't know existed = with=20 it...prob because of the wider beam width. i was = pointing the=20 patch straight out the front of my windshield so the = 60deg=20 beamwidth was probably working against it. there is no = comparison between the 2 for signal strength/SNR = comparisons=20 when the patch is pointed correctly. also, you need to = rotate=20 the patch for max gain...it can change the SNR by = several=20 dB.

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Last edited by=20 lincomatic on 06-02-2002 at 12:41 AM

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06-02-2002 12:34=20 AM

=20 =

lincomatic
UberNetbumbler

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

EYE CANDY=20

found some=20 very interesting stuff tonite. BW yr gonna blow yr wad = when u=20 see these 3D""=20

Lucent Omni...(really a = maxrad)...see page=20 13
http://gullfoss2.fcc.gov/prod/oet/forms/blobs/retrieve.cg= i?attachment_id=3D37613&native_or_pdf=3Dpdf
looks=20 kind of guerrilla.net's 2nd collinear design,=20 no?

Lucent Yagi. antenna innards are somewhere = in the=20 middle of the doc. also tons of pics of the inside of = the=20 ORiNOCO silver/gold card:
http://gullfoss2.fcc.gov/prod/oet/forms/blobs/retrieve.cg= i?attachment_id=3D37614&native_or_pdf=3Dpdf
the=20 antenna looks a lot like one of the kool yagis i found = on=20 seattlewireless.net (link is somewhere earlier in this = thread). maybe that's just a copycat?

Avaya = PCCARD=20 (same as ORiNOCO)
http://users.skynet.be/chricat/Avaya.html
Buffalo = (ORiNOCO again)
http://users.skynet.be/chricat/WLI-PCM-L11-3.html
= DLink=20 DWL-650
http://users.skynet.be/chricat/DWL-650.html
Linksy= s=20 PCMCIA NIC
http://simon.barber.net/linksys/default.htm
http://users.skynet.be/chricat/linksys.html
Linksy= s=20 USB NIC
http://www.kcip.com/wireless/wusb11.html