NetStumbler.com Forums - Post Your Homebrew Antennas = Here

From: Subject: NetStumbler.com Forums - Post Your Homebrew Antennas Here Date: Wed, 10 Jul 2002 12:21:02 -0700 MIME-Version: 1.0 Content-Type: multipart/related; boundary="----=_NextPart_000_0085_01C2280C.41AEF9A0"; type="text/html" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 This is a multi-part message in MIME format. ------=_NextPart_000_0085_01C2280C.41AEF9A0 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=3 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

Pages (4): = =AB=20 1=20 2=20 [3] 4=20 =BB=20

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Author

Thread

sparafina
yatta!

Registered: May=20 2002
Location: AUS/LAX/DCA
Posts: = 147

Oops, I was=20 so excited I forgot to check and see if the photo was=20 copyrighted. I'll edit the post and remove the = picture. Here's=20 the FCC ID: IMRWLPCE24H and the link (from BW, muchas=20 garcias):

http://gullfoss2.fcc.gov/prod/oet/forms/blobs/retrieve.cg= i?attachment_id=3D37613&native_or_pdf=3Dpdf

FYI,=20 the acrobat document maintains the original resolution = of the=20 photo inserted into the document. You can zoom in = pretty far,=20 e.g. 600% before it starts to pixelate, which is = enough to=20 make useful measurements for comparison.

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06-10-2002 11:01=20 AM

=20 =

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

Registered: Apr=20 2002
Location: SoCal, OC
Posts: = 1806

quote:
Originally posted by sparafina
Here's = the FCC=20 ID: IMRWLPCE24H and the link (from BW, muchas=20 garcias):

Though I do not recall, I am sure = I got=20 this info from lincomatic and his hard k0re = nude=20 'tronics links.. 3D""=20

Thanks lincomatic!

__________________
-=3DBW=3D-

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06-10-2002 11:06=20 AM

=20 =

lincomatic
UberNetbumbler

Registered: Apr=20 2002
Location: Tanimbar Islands
Posts: = 739

bmoore314 has posted some interesting = photos and=20 info
on "cantennas" in the thread:

my = wireless=20 setup
http://forums.netstumbler.com/showthread.php?s=3D&thr= eadid=3D2207

__________________
~lincomatic

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06-12-2002 12:12=20 PM

=20 =

sparafina
yatta!

Registered: May=20 2002
Location: AUS/LAX/DCA
Posts: = 147

g.net omni = vs=20 maxrad=20

I = compared=20 the measurements of the g.net low powered omni to that = to the=20 maxrad picture and they match up pretty well, about 1 = mm off=20 due to pixelation. The construction is the same, even = the=20 coils match. The only thing I could'nt measure was the = decoupler length. From my understanding of this = design, you=20 can tune a collinear based on the length of the=20 decoupler.

That being said, I still don't = understand=20 the principles behind this antenna especially after = looking at=20 the collinear designs that use coax, where the last = section is=20 a 1/4 wave length.

It's hard to judge its = performance,=20 because I'm using it in an unfamiliar area. I've been = using my=20 antenna at freeway speeds (75+), and the window mount = has held=20 up. However, I thought of a new magnetic mount design = for=20 these larger antennas. Will post a pic when I build=20 it.

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06-12-2002 11:31=20 PM

=20 =

lincomatic
UberNetbumbler

Registered: Apr=20 2002
Location: Tanimbar Islands
Posts: = 739

Re: g.net = omni vs=20 maxrad=20

quote:
Originally posted by sparafina
I = compared the=20 measurements of the g.net low powered omni to that = to the=20 maxrad picture and they match up pretty well, about = 1 mm off=20 due to pixelation. The construction is the same, = even the=20 coils match. The only thing I could'nt measure was = the=20 decoupler length. From my understanding of this = design, you=20 can tune a collinear based on the length of the=20 decoupler.

That being said, I still don't = understand=20 the principles behind this antenna especially after = looking=20 at the collinear designs that use coax, where the = last=20 section is a 1/4 wave length.

It's hard to = judge its=20 performance, because I'm using it in an unfamiliar = area.=20 I've been using my antenna at freeway speeds (75+), = and the=20 window mount has held up. However, I thought of a = new=20 magnetic mount design for these larger antennas. = Will post a=20 pic when I build it.

Ha! pilfered design as we = suspected,=20 despite their claim:

This is a follow up = design that=20 culminated everything we learned from building the = first=20 collinear antenna

thanks for taking the = time to=20 spec out the maxrad.

the calculations regarding = phasing=20 coil design are really puzzling me in both this design = and the=20 mobile mark. isn't the idea of phasing coils just to = eat up=20 enough wire length to get the straight parts in phase? = there=20 must be some other effects that i'm not accounting for = because=20 the numbers don't make sense to me.

btw, here = is=20 another collinear that some of the satellite hams are = using,=20 built up of 5/8 and 3/4 wavelength elements:

http://www.qsl.net/vk3jed/2400_MHz_antenna1.JPG
http://www.qsl.net/vk3jed/2400_MHz_antenna2.JPG
it=20 uses u-shaped sections instead of coils for=20 phasing.

looking fwd to seeing your new = magmount=20 design...

__________________
~lincomatic

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06-13-2002 01:56=20 AM

=20 =

sparafina
yatta!

Registered: May=20 2002
Location: AUS/LAX/DCA
Posts: = 147

I = doubt if=20 I'll build the Pringles yagi/waveguide/whatetever, but = I=20 thought this would make a classier alternative to the=20 ubiquitous Pringles can. Definitely much more=20 enjoyable.

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

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06-16-2002 08:15=20 PM

=20 =

eric650
Net = Stumbler

Registered: Jun=20 2002
Location:
Posts: 77

@lincomatic=20

Hey=20 lincomatic, can you tell me exactly what your N jack = is? Like=20 the exact part number and from where you got it. I = want to=20 build an antenna just like yours. Thanks.

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06-19-2002 01:47=20 PM

=20 =

lincomatic
UberNetbumbler

Registered: Apr=20 2002
Location: Tanimbar Islands
Posts: = 739

Re:=20 @lincomatic=20

quote:
Originally posted by eric650
Hey = lincomatic,=20 can you tell me exactly what your N jack is? Like = the exact=20 part number and from where you got it. I want to = build an=20 antenna just like yours. Thanks.

i got mine at a local radio = supply house.=20 it was in an unmarked bag so i don't have a part = number but=20 you can get it here:

http://www.pl-259.com/page1.html

it's=20 the N female chassis mount, 4-hole = $2.00

btw=20 which antenna are you going to build?

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

__________________
~lincomatic

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06-19-2002 01:55=20 PM

=20 =

eric650
Net = Stumbler

Registered: Jun=20 2002
Location:
Posts: 77

the one that=20 you started this thread with = :P

Thanks.

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06-19-2002 02:33=20 PM

=20 =

eric650
Net = Stumbler

Registered: Jun=20 2002
Location:
Posts: 77

oh yes, that=20 n jack will hook up directly to the orinoco card with = the=20 other pigtail cable I need to buy right?

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06-19-2002 02:35=20 PM

=20 =

sparafina
yatta!

Registered: May=20 2002
Location: AUS/LAX/DCA
Posts: = 147

Score!=20

Whilst=20 looking for a laptop to build a linux wireless access = point at=20 Goodwill, I found an old ISA Rangelan2 card with an = antenna=20 for $10. The antenna turned out to be the 2 dbi model, = way=20 cool.

Yes, I started taking it apart, but its = pretty=20 well constructed and I would trash the nice plastic = case to=20 see what's inside. Based on sqeezing and bending the = antenna=20 (no comments please), I think that its a 1/4 wave whip = with=20 some kind of coil. The base has a big plate that = probably acts=20 a ground plane. Any way, I'm retiring the yogurt cup = toothpick=20 in favor of this thing. A couple of quick mods - = adding a=20 magnet to the base and soldering an N connector - and = I should=20 be stumbling in style.

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

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06-19-2002 02:37=20 PM

=20 =

lincomatic
UberNetbumbler

Registered: Apr=20 2002
Location: Tanimbar Islands
Posts: = 739

quote:
Originally posted by eric650
oh yes, = that n=20 jack will hook up directly to the orinoco card with = the=20 other pigtail cable I need to buy right?

yes. make sure the pigtail u get = has an=20 N-Male, not Female.

__________________
~lincomatic

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06-19-2002 02:38=20 PM

=20 =

lullabud
UberStumbler
3D""=20

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

Re: = Score!=20

quote:
Originally posted by sparafina
Whilst = looking=20 for a laptop to build a linux wireless access point = at=20 Goodwill, I found an old ISA Rangelan2 card with an = antenna=20 for $10. The antenna turned out to be the 2 dbi = model, way=20 cool.

Yes, I started taking it apart, but = its pretty=20 well constructed and I would trash the nice plastic = case to=20 see what's inside. Based on sqeezing and bending the = antenna=20 (no comments please), I think that its a 1/4 wave = whip with=20 some kind of coil. The base has a big plate that = probably=20 acts a ground plane. Any way, I'm retiring the = yogurt cup=20 toothpick in favor of this thing. A couple of quick = mods -=20 adding a magnet to the base and soldering an N = connector -=20 and I should be stumbling in style.

dude! how lucky can you = get??

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06-19-2002 03:24=20 PM

=20 =

sparafina
yatta!

Registered: May=20 2002
Location: AUS/LAX/DCA
Posts: = 147

Re: Re:=20 Score!=20

quote:
Originally posted by lullabud
dude! = how lucky=20 can you get??

Well, I did find a working = notebook=20 (Epson ActionNote 650c) for another $10. I'm going to = use this=20 as an access point for testing all those antennas I = built.=20 Something Eventually, I'm gonna stick it in the attic = for a=20 WIPOP, so my kids and their friends will have a never = ending=20 LAN party.

Oh yeah, and I have phenomenal = parking=20 karma this year.

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06-19-2002 04:24=20 PM

=20 =

lullabud
UberStumbler
3D""=20

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

you should=20 take your fantastic luck and buy stock or something. = just let=20 me know who you're investing in so i can mirror your=20 purchasing. =3D)

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06-19-2002 04:30=20 PM

=20 =

sparafina
yatta!

Registered: May=20 2002
Location: AUS/LAX/DCA
Posts: = 147

quote:
Originally posted by lullabud
you = should take=20 your fantastic luck and buy stock or something. just = let me=20 know who you're investing in so i can mirror your=20 purchasing. =3D)

I think that the good parking = karma is=20 the consolation prize for market losses.

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06-19-2002 04:46=20 PM

=20 =

lincomatic
UberNetbumbler

Registered: Apr=20 2002
Location: Tanimbar Islands
Posts: = 739

sparafina posted his measurements from = outcast_one's photos of the mobile mark in = another=20 thread. i've copied his msg below in case anyone is=20 = interested:
--------------------------------------------
quote=20 sparafina:

Here are my=20 measurements:

Groundplane to beginning of coil: = 34 mm=20 (roughly 1/4 wave?)
Coil: 14 mm, 3 turns with 4mm = between=20 each full turn
Coil width: 7 mm
Coil to end: 62 = mm (~1/2=20 wave)
Groundplane is about 80mm in = diameter

I'm not=20 sure if a decoupler is needed (don't see one), but its = pretty=20 important for collinears from the ham stuff I've been = reading.=20

So far, I've got the wire bent, I think I have = an old=20 harddisk drive platten for a ground plane. I bought a = new=20 microwave and I salvaged the magnets from magnetron = for a mag=20 mount. I'll post pics when I'm done.

end=20 = quote
--------------------------------------------------

i = built one myself but it sucked pretty bad...the gain = was WORSE=20 than the built in orinoco antenna.

my own=20 measurements:
ground plane to coils: 34mm (9.5mm of = that is=20 under the black plastic bump..wonder what's in=20 there?)
wire: ~1.5mm OD
length of coils: = 13mm
coil=20 ID: 5mm
coil OD: 7mm
coil spacing: = ~3-3.5mm
coils to=20 top: 51.5mm+13mm(plastic tip)..wonder how high the = wire goes=20 into the tip.

i used solid copper wire cut out = of a=20 piec of romex...forget the gauge..it was all i had = available;=20 tried initially to bend a coat hanger but the steel = wire was=20 too difficult to bend into the coils.

i think = the=20 problem w/ the bad performance i got is that there is = too much=20 uncertainty in measuring from the photos...even 1-2mm = off in=20 the dimensions @ 2.4GHz can mess it up pretty=20 badly.

btw, mobile mark's spec for the antenna = show a=20 3" diameter ground plane which is a little smaller = than 80mm,=20 but i don't think it's that critical.

__________________
~lincomatic

Last edited by=20 lincomatic on 07-05-2002 at 01:20 AM

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07-05-2002 01:02=20 AM

=20 =

lincomatic
UberNetbumbler

Registered: Apr=20 2002
Location: Tanimbar Islands
Posts: = 739

if at first you don't succeed, try try=20 again=20

ok sparafina,=20 ya got my interest piqued again. what kind of dork is = building=20 an antenna @ 2:30AM on July 4? me. but hey, it's July = 5 now=20 anyway.

this time i was able to bend the wire = more=20 accurately, and it works a lot better. but i must say = its=20 performance is rather underwhelming. went outside and = compared=20 the gain against my toothpick, and performance was = about the=20 same. about the only diff is it seems to be less = sensitive to=20 polarization effects. i guess the real acid test will = be=20 stumbling with it. but since it's made of copper wire = it's=20 going to be difficult to keep its shape under all the = abuse i=20 give my antennae.

below is a pic of the two = antennae=20 side by side. once again i used a 3" can lid for the = ground=20 plane.

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

__________________
~lincomatic

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07-05-2002 02:37=20 AM

=20 =