Any one got information as I need to shoot a link about 600 metres and
am thinking a home made slot would be the ticket . (and ues its los if I
go up 10 metres whixh means 15 metres of coax all up)

On Fri, 04 Mar 2005 15:40:12 +1000, atec <"atec77(ate***@hotmail.com>
wrote:

I'll assume 2.4GHz.  4 slot antenna:

http://www.austwireless.com/catalog/product_info.php/cPath/23_48_170/products_id/195
Only $365/ea.

Wanna disclose what you're trying to accomplish, what you have to work
with, and why you think a horizontally polarized slot antenna, which
is normally used as a sector antenna, is the "ticket"?

Jeff Liebermann wrote:
Show quoteHide quote  no I don't , I do know its the way to go , for my purposes.
  nice link but Ill have to find more as I said I intend making one or
two of then , now why you assume its horizontal in polarisation ?
Show quoteHide quote

On Fri, 04 Mar 2005 16:16:35 +1000, atec <"atec77(ate***@hotmail.com>
wrote:

Show quoteHide quoteI assumed horizontal polarization because vertically mounted slot
antennas are almost always horizontally polarized.  That's because you
can build a vertically polarized sector antenna, with similar
characteristics, much easier and cheaper using a vertical colinear.

It is possible to design a vertically polarized slot antenna, but the
geometry and pattern are rather odd looking.  These were used for
early WWII era aircraft night-fighter RADAR, where the antennas were
waveguide slots on the leading edge of the wings.

The link above is horizontal polarization.  The various examples of
Alford Slot antennas are all horizontally polarized.
  http://www.eta.chalmers.se/~pgp/alford_slot/alford_eng.html
The various examples derived from the design by Trevor Marshall at:
  http://www.trevormarshall.com/waveguides.htm
are all horizontal.  Incidentally, the above article gives dimensions
and construction details for milling your own.  More:
  http://www.seattlewireless.net/index.cgi/SlottedWaveguide

Another $300 antenna:

http://www.freenet-antennas.com/~freenet-/oscommerce-2.2ms2/catalog/product_info.php?products_id=166

Horizontal polarization has some really nice advantages when dealing
with interference as most everyone else is using vertical
polarization.

Good luck, whatever you're trying to do.

Jeff Liebermann wrote:
Jeff Liebermann wrote:
Show quoteHide quote From the house to the office , why buy two  dsl 3 mbs ?
  I've opted for waves because I can make them in the neighbours shop ,
with a corner refletor and a vpn should do the trick and it will be
cheap Im sure ..
  plenty of 9913 here and lots of connectors so I figure about an hour
each plus install at almost nothing  each with coax .
  looking at the retail prices Im glad I have the facilities .

On Fri, 04 Mar 2005 16:51:42 +1000, atec <"atec77(ate***@hotmail.com>
wrote:

Why?  Well, your ISP's terms of service may restrict redistribution of
bandwidth off the property limits.  Of course, few enforce such
restrictions and everyone does wireless, so I think you're probably
safe.

Watch your tolerances.  See the ACAD DWG on Trevor Marshall's site.
Note the tolerances.  They're tight.  I worked out the numbers in
another posting but the total error to drift out of the 2.4Ghz band
for a 1/2 wave dipole is something like 1.5mm max.  This is not
something you can build with a drill, file, and tape measure.

9913 is not too good at 2.4Ghz (0.62db/meter @ 2.4Ghz).  I prefer
LMR-400 (0.22dB/meter) but 9913 is good enough for short runs (less
than about a meter). 

May I recommend you build a pair of biquad antennas instead.
  http://martybugs.net/wireless/biquad/
  http://www.trevormarshall.com/biquad.htm
Leave the coax fairly long so that you don't need a pigtail.  I dunno
about finding a reverse TNC connector for 9913.  Therefore, I suggest
a male N connector, and buying a female N to R-TNC adapter.
  http://www.sky2web.net/rptncf-adapter.html
I hate to admit it, but I use RG-6/u and RG-58c/u for my biquads.
Very lossy, but for short runs, the coax doesn't have much effect.

Good luck.

Jeff Liebermann wrote:
  it may , but there are ways , and seeing I have a fiscal interest it
doesn't matter ..
  didn't read it did you  . he has a serious machine shop , so a
vertical cnc and 20 minutes to set it up. easy
  I'm a contractor and install all sorts of things as part of my
business, just found 40 metres of hard core .. any other problems ?
  not interested in quads , been there and they work but because of the
situation at the office the slots will be almost invisible so that's
what I'm using , thanks anyway ... will have them made in another hour
or two and fit tomorrow...
Show quoteHide quote

On Fri, 04 Mar 2005 17:58:25 +1000, atec <"atec77(ate***@hotmail.com>
wrote:

Yeah.  You mentioned using 15 meters of coax.  That's 9.3dB of loss
for 9913 or about 85% of your power gone up in smoke.  Methinks that's
way too much coax.  If you switch to LMR-400, you'll still lose 3.3dB
or a bit more than half your power, which is much better.  Lose the
9913 please and buy some LMR-400 (or bigger).

This you call monster invisible?
  http://jefflaplante.com/waveguide/waveguide_01.jpg
  http://jefflaplante.com/waveguide/Matt_waveguide.jpg
Well ok.  The machine shop will be a big help.  Good luck.

On Fri, 04 Mar 2005 08:14:53 GMT, Jeff Liebermann
<je***@comix.santa-cruz.ca.us> wrote:

One more slot antenna:

http://nuke.freenet-antennas.com/modules.php?name=News&file=article&sid=1
This one is quite different from Trevor Marshall's.  I dunno about the
zinc plates steel "downpipe" used.

Jeff Liebermann wrote:
Show quoteHide quote  don't know what hard-line is do you ?
  never mind , its the stuff you need a plumbers knowledge for
  think 6 metre high industrial building with high placement on a couple
of tinted windows , which is where the slot will go and on the inside of
the window will be essentially invisible , I see a certain degree of
assumption on your part which truthfully Id like to see you address , as
I said I do this sort of thing for a living , lots of dishes and
telephony so I do have some advantage .
  looking at the house I will mount the stick about 6 metres off the
roof and place the ap inside with some hard-line up and cat5 down. easy
and cheap
  just so you know next time its Belden 1573A
  if I had to pay for it Id be very unhappy :_)
Show quoteHide quote

On Fri, 04 Mar 2005 18:43:29 +1000, atec <"atec77(ate***@hotmail.com>
wrote:

I used to work with lots of aluminium jacketed CATV coax of various
dimensions.  Bending the larger stuff requires an EMT bender.  That's
hard line.  9913 is aluminium foil and braid, which is NOT what I
would call hard line.  It's usually listed as "low loss RG-8/u".

yeah, that will work if you mount it in the middle of the window.  One
problem with such a sector or omni antenna is that you can't really
put it next to anything metallic or reflective as it will wreck the
pattern and possibly increase the VSWR.  So, you plan to spoil
someones view by planting it in the middle of their view?  Actually,
that's not a bad idea.  Plant the lower end into a flower pot, add
some soil for stability, decorate with plastic plants, and it will be
invisible.

Incidentally, some "energy efficient" tinted windows are aluminized
and block RF.  I suggest a fast test to make sure they'll work.

Agreed.  I do badly with insufficient information.  I like numbers.

I guess math isn't part of the job requirement.  You're installing 15
meters of fairly high loss coax cable to a 1.5 meter long antenna that
is being used for a point to point link and delivers perhaps 15dBi
gain on a 180 degree sector.   Meanwhile, a 14dBi panel antenna is
perhaps 200mm x 200mm for the same gain and a narrower 35 degree
beamwidth (so you don't have do deal with reflections).  You "found"
the 9913 which is not commonly used at 2.4Ghz as a simple loss
calculation will show.

It took me a while to find Belden 1573A data.  It's not in the online
version of the Belden catalog.  Google found one reference to Belden
1573A which claims it's the same as RG-402 which is 0.141" semi-rigid
cable.  I use the stuff for short jumpers, SMA patch cables, phasing
lines, and pigtails from PCMCIA cards with no antenna connector.  The
loss is 0.875/meter at 2.4GHz which has more loss than 9913.  Just to
make life interesting, Belden recycled the part number which was an 8
pair #24 awg cable, but is now obsolete.

At 600meters link distantce, your proposed arrangement should sorta
work as described, even with the lossy coax.
  Range:  0.373 miles (600 meters)
  TX power: +15 dBm
  TX ant gain: +14 dbi
  TX coax loss: -9dB  (15 meters 9913)
  RX send: -83 dBm
  RX ant gain: +14 dbi
  RX coax loss: -9dB  (15 meters 9913)
Using:
  http://www.terabeam.com/support/calculations/som.php#calc
I get 12.4dB fade margin, which should be sufficient to get a marginal
and flakey connection.  I suggest you do something about the coax
loss.

Jeff Liebermann wrote:
Show quoteHide quoteI did find something else  , used semi-rigid found in the shed ( 600
series), measures well and on testing we got a nice solid signal
(matching my figuers) ,  you might re-read the thread , I moved the
goalposts and ran only 6 metres of feed which of course gives perfectly
acceptable results for a total cost of a couple of a few beers and some
time.
Happy ?
  yup sure am .

On Fri, 04 Mar 2005 18:43:29 +1000, in alt.internet.wireless , atec
<"atec77(ate***@hotmail.com> wrote:

And you might want to check out Jeff's credentials.

luck will be needed...


I believe Jeff does too.

Mark McIntyre <markmcintyre@spamcop.net> wrote:
Good Lord, *don't* entice him!  Jeff's CV is probably 2000 pages
long and lists the path margin on every system he's ever
implemented... ;-)

....
With a little difference too.  Jeff is doing the systems
engineering, not just installation.  He's figuring out *what* to
install, not just how and where.

A *very* significant difference...

Floyd L. Davidson wrote:
Show quoteHide quote  bound to be boring .
  See boring , no need
  1/2 his luck as it can be fun and often very challenging .
  yup , I have a couple of weeks in the field  and he knows in theory ,
after 25 years and a couple of weeks schooling I do have an idea now and
then that works :_)
Show quoteHide quote

On Sat, 05 Mar 2005 09:03:08 +1000, in alt.internet.wireless , atec
<"atec77(ate***@hotmail.com> wrote:


you're saying you have a couple of weeks field experience? And Jeff only
has theoretical experience? You're insane.

Many many field-taught engineers have said that. Generally shortly before
the cathedral fell down / dam burst / aeroplane's wings fell off etc.
Still, its up to you.

Mark McIntyre wrote:
Show quoteHide quote  I guess you don't understand dry as a desert humour ,

On Sun, 06 Mar 2005 10:58:19 +1000, in alt.internet.wireless , atec
<"atec77(ate***@hotmail.com> wrote:

or possibly you just aren't funny?

Mark McIntyre wrote:
Oh I am , just very dead pan , not something your side of the water oft
appreciates.

On Fri, 04 Mar 2005 20:31:34 +0000, Mark McIntyre
<markmcintyre@spamcop.net> wrote:

If I had any common sense, I would avoid such personality clash
discussions.  It try to exclusively deal with a persons ideas,
calculations, conclusions, and recommendations, and completely ignore
any character references.  However, since I lack common sense and
since this seems to be about me, I'll make an exception, especially
since I'm my own favorite topic of discussion.  (My most recent resume
is about 1985).

I think you'll find my credentials to be rather lacking compared to
others in this newsgroup.  I found my most recent resume from 1983.  I
don't think that will help.  BSEE from Cal Poly Pomona in about 1971.
Between about 1968 and 1983, I've worked for or owned something like
14 businesses, all of them in 2-way radio (PMC), marine radio (Intech
Inc), avionics, and related areas.  Several of my projects and designs
were analog and early digital microwave radios (Granger Assoc).  Throw
in a few military adventures, a print shop, some spook stuff I can't
talk about, and lots of consulting to keep me entertained. 

In 1983 I magically declared myself to be a computer consultant with
no more credentials than owning an original 5150 IBM PC (4.77MHz).
Since there was nobody around who could explain anything, no time for
classes, and only the IBM Tech Ref manual, I used the "Learn by
Destroying" method.  I helped fix PC's at a local clone dealer in
trade for referrals.  Fairly soon, I was in demand and had a new
career.  I decided that the skools were going to crank out programmers
by the millions, so I elected to stay in the hardware end of
computahs.

1986 thru 1995 revolved around family demands and basically prevented
me from taking on any major projects, new businesses, growing the
business, or long term commitments.  So, I mixed computer consulting
with fast fix type of consulting and design projects, mostly in radio
design and SNMP monitoring.  I developed reputations as a problem
solver and as a market analyst, which offered work in ISP SNMP
monitoring, network troubleshooting, and wireless, which at the time
was not much better than magic.  Throw in editing a few books, and
some really weird research and report writing.  I also was involved in
trying to setup 2.4GHz WISP service locally, which was severely
handicapped by the dense forest and mountains.  I gave up, but learned
quite a bit in the process.

In 2001, I had a medical crisis which required that I abandon my 60
hour work week and do something less suicidal.  I continued to do
computer repair and consulting (because it's easy) and set myself up
as a wireless "system designer and troubleshooter" or something like
that.  Basically, I do the calculations, designs, offer sanity checks,
make recommendations, make suggestions, pass judgment, run lab tests,
and stay away from towers and rooftops.

I'm 57 years old, and suspect that I've made enough mistakes to be
considered "experienced".  I'm far from retired.  A good self
description would be that I'm a "curmudgeon".  Nobody, except myself
and several ladyfriends, have ever accused me of being boring.

I sorta believe in karma and luck.  I try not to rely on them.
Therefore, I do my calculations before I dive into anything marginal.
If it doesn't work on paper (or on the computah model), it probably
won't work when assembled or built.  Specs and estimates are never as
good as the data sheet or computah model claims.  However, there is
always luck...

Not really.  I don't get my hands dirty any more.  Mostly system
planning and troubleshooting these days.  Much of my wireless
experience is from about 5-8 years ago and is limited to specific
hardware and applications.  That's like the stone age in the wireless
biz.

There's plenty that I don't know.  WDS is a good example.  I've never
done a WDS system, and haven't researched WDS at all.  So, with
infinite wisdom and overconfidence, I recently posted an erroneous
explanation of the effects of store and forward on DSL bandwidth.
Floyd Davidson posted a correction and I admitted fault.  That's quite
different from this discussion which seems to have degenerated towards
a personality attack.  In my never humble opinion, the mark of
experience and expertise is the willingness to stretch that experience
and expertise into unfamiliar areas, to accept advice and criticism,
and to understand and admit errors when made. 

We all tend to forget what it was like when we started out.  I still
remember some of the grand schemes and great ideas that were far from
optimal or even functional when I was twenty something.  I would cling
to some plan well beyond where a reasonable person would give up
simply because it was *MY* great idea.  Mr Atec is apparently just
getting started and has a way to go.  Methinks he seems willing and
ready to make his own decisions and mistakes.  Time will tell if he
profits by them.

Jeff Liebermann <je***@comix.santa-cruz.ca.us> wrote:
Actually, Jeff, you are probably the premier guru in this newsgroup,
and we all appreciate your knowledge, wit, and helpfulness.  Hang in
there!

Jeff Liebermann <je***@comix.santa-cruz.ca.us> wrote:
Ha, I warned 'em not to entice you!  Of course, you *were* nice
enough to not post all 2000 pages, but I *was* looking forward
to details of the path margins on every single radio you've
installed...  ;-)

Yer a @#$%^&* old knob twister...

On Sat, 05 Mar 2005 12:09:39 -0900, fl***@barrow.com (Floyd L.
Davidson) wrote:

Careful what you wish for.  You might get it.  I ran out of "free" web
space a few months ago and removed all my Radio-Mobile coverage maps
and JPG's from my web pile (and replaced them with pictures of
myself).  There were only about 30 coverage maps but I do have more.
Some were mesh type overlapping coverage maps included point to point
fade margin calcs.  Oops, I left one in place.  See:
  http://www.LearnByDestroying.com/maps/k6bj3-3d.jpg
It's a bad guess as to the VHF coverage of one of the local ham
repeaters (elevation 250ft) that I helped build.

Here's another of my web piles with coverage and link info:
  http://cellular.ihwy.com
However, it's now 4 years out of date (due to lack of time) and only
one page has any coverage photos:
  http://cellular.ihwy.com/jeffl/SVLY-PGE/index.html
So many projects, so little time.

I automated that years ago.

Jeff Liebermann <je***@comix.santa-cruz.ca.us> wrote:
Put the maps back.  You're almost as ugly as me.

See, stuff like that is worth looking at!  Right?

I poked around and looked at some of the other pictures too.
You are obviously having far too much fun.

I looked at some of the other pictures there too.  Interesting.

Regardless, yer obviously a knob twister!


(All jokes aside, I *did* enjoy looking at the pictures.)

atec" <"atec77(atec) wrote:
How about a USB connected transciever, no coax, that can be a ways away from
the computer, and small enuf to stick to/be part of a panel/dish/yagi
antenna? Boy.. I could use and sell a few of those....

Peter Pan wrote:
My friend just suggested an addition... Have both a USB and Ethernet (and
power) connection for runs longer than USB can handle, but within reach of
ethernet.

Peter Pan wrote:
there is such a thing available . but I figure with a couple of hours of
my time , an ap and everything done with a bit of luck I have most of it
including a 2000 dlink ap , will be chap ( only way to do it)

Isn't USB limited to something like 15 feet?

I'd say that either mounting the radio itself up 10 metres, or
spending a caboodle on expensive feedline, is the only solution.

I'd check out various units intended for remote mounting, with a
data/power connection using CAT5 cable.  They may not
inexpensive, but neither is waveguide for 2GHz!

hi,
have you seen the multi-polarized antennae(some call em snake-oil!) on
www.wifi-plus.org?
i found another site selling the same stuff under their own brand (OEM
or ODM?)
www.hautespot.com
their tetrads should suit your purpose i guess.

Floyd L. Davidson wrote:
Show quoteHide quoteThat was what my buddy said was the reason for wired ethernet. For close by
indoor use (like up off the floor since a lot of people put their cpu's on
the floor, with something like a semi or panel that the wap could clip too,
and the ethernet that can be several 100 ft away, could be placed inside
(like the attic by an outer wall with a panel or dish etc).
Seems like the biggest loss is trying to run coax to an antenna, why not
usb/ethernet and have the whole enchilada placed a bit away, somewhere
convenient?

I started wondering why they don't make em like that, I travel in an RV, and
having a USB device that I can move around and put in a window, or up high
on the roof, is usually a good thing..

Show quote Hide quote I've seen at least a couple units made like that!  Designed to
be externally mounted, with power and data fed over CAT5 cable.
Of course these things cost a good bit more than the consumer
grade products that most of us talk about here... :-)

I wonder about that restriction on USB cable length too.  I have
no idea just exactly what limits it to 15 feet, but I suspect it
might be the power leads rather than the data.  If that is true,
it might be that a device which uses significantly less than the
maximum power could actually be used on significantly longer
cables.

I've got a couple of 15 foot USB extention cables here
somewhere, and someday I'm going to test that to find out...
But I don't have any USB wifi devices, so whatever tests I
might do wouldn't necessarily apply to those.

On Fri, 04 Mar 2005 02:26:40 -0900, fl***@barrow.com (Floyd L.
Davidson) wrote:

I did some disorganized tinkering with extension cables and can offer
some anecdotal evidence.  I was able to locally power a WUSB54G with
5.0VDC and get it to somewhat function using one pair from a 50ft
piece of CAT5E cable.  The xmit signal was 1.5 volts peak to peak and
the received signal was about 400mv p-p when it crapped out.  That's
about 10dB of cable loss where the max length can be calculated for
various cables.

There are also rise time and timing delay specs, which I don't claim
to have read:
  http://www.usb.org/developers/usbfaq/
There's quite a bit in there...

I had trouble trying to figure out why my local 5V power would stick
the device in USB 1.1 mode instead of 2.0.  It seems that one has to
have a common DC power ground so that one of the data lines can be
pulled high (3.3v) to indicate it's a USB 2.0 device.   Grrrr...
  http://www.beyondlogic.org/usbnutshell/usb-in-a-nutshell.pdf
See Fig 2 and 3.  I never did get it working correctly because of all
the DC level signaling that was required.  More:
  http://www.maxim-ic.com/appnotes.cfm/appnote_number/1822

Specifications on a "typical" USB chip.  See:
  http://pdfserv.maxim-ic.com/en/ds/MAX3346E.pdf
Note the input sensitivity of 200mv with a hysteresis of 250mv. Same
here:
  http://www.micrel.com/_PDF/mic2550a.pdf
If I read that correctly, the receiver needs 450mv p-p input to work.

Incidentally, the WUSB54G apparently functioned down to an applied
voltage of about 3.8VDC.  However, I kept getting stuck with USB 1.1
mode instead of 2.0 so that's not really totally functional.

I can re-measure any of the above.  However, I'm down to my last scope
probe and can't really measure the signal levels without pair of
probes with the scope in differential input mode.

Floyd L. Davidson wrote:
Show quoteHide quoteCan save you the trouble... I have one of those little "dongles" that plug
into a USB port on a computer or other device (a few oz'z and an inch or so
long). I was experimenting and trying it with USB extension cables rather
than plugging it in directly into my laptop. When the USB extension cables
are added on, you start getting more errors (at about 45 FT it becme so
error ridden it was unusable), that's when my partner at work suggeted
ethernet (they make and sell Power over Ethernet devices) and can go about
100M (348ft). When I started looking, all I could find was pre-made USB
"dongles", and started wondering why there are no ethernet dongles (they do
make ethernet to usb converters, I have one on order for my DVR - USB output
only, but ethernet on my home network).. Sure would be neat to have ethernet
dongles that can just plug into an ethernet port and be on the network.

As for cost, the USB dongles are about $35 (ethernet to USB converter is
about $18), with economy of scale, I would suspect they would be under $50
if made together in one package, and rather than an internal antenna, a
mini-uhf connector to hook to external antennas to it, should make a
negligable difference in cost. Just to be clear, they make consumer grade
USB "dongles", adding ethernet and POE options, Seems like it would be a
perfect consumer grade device.

On Thu, 03 Mar 2005 23:10:10 -0900, in alt.internet.wireless ,
fl***@barrow.com (Floyd L. Davidson) wrote:

You can boost it to longer lengths. Over 5M you'll need a power supply. In
the UK you can buy extender cables in places like www.maplin.co.uk and over
in the astronomy / webcam groups you will read about people remote
controlling telescopes and cameras via USB from the comfort of their living
rooms.

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