"Glenn Ashmore" wrote in message
...
I think it would be wise to learn something about 2.4ghz wave propagation
and the Fresnel effect before you make that statement. If you just want a
couple of hundred yards range deck mounting is fine but for 2 miles plus
you need to be UP.

Bullocks. I happen to know by personal experience that low is better. Even
the manufacturer recommends deck top mounting.

By far the best solution is a waterproof wifi bridge at the masthead
connected by Ethernet with POE to a hub. Long range because there is
minimal coax loss and a wide Fresnel zone.

Bullocks again. KISS! Keep it simple, stupid. The more complicated it gets
the more failure prone it is. What happens to any antenna at the masthead at
anchor and even moreso under way? You have wind shaking it around, You have
the roll and pitch of the boat swaying it around. You have the heel pointing
it in all the wrong directions. You have static electricity going on at the
mast head. And watch out for any nearby lightning strike. WIPEOUT!

I am a sailor. I've been a sailor most of my life. I know what works and
your ideas won't! For lubbers maybe but for sailors, forget all about it.

And, BTW. What's with the top-posting? If you can't even learn how to post
correctly why is it you think people should take you seriously about
anything else?

Wilbur Hubbard

"Glenn Ashmore" wrote in message
...
I think it would be wise to learn something about 2.4ghz wave propagation
and the Fresnel effect before you make that statement. If you just want a
couple of hundred yards range deck mounting is fine but for 2 miles plus
you need to be UP.

By far the best solution is a waterproof wifi bridge at the masthead
connected by Ethernet with POE to a hub. Long range because there is
minimal coax loss and a wide Fresnel zone.

The pattern of coverage from the antenna is crucial. Something with a high
gain might work great when you're a mile or two offshore, but will work
horribly when you're in a marina. The pattern from most omnidirectional
antenna resembles a 'donut'. The higher the gain the 'wider' the donut will
be, but it'll be more compressed vertically. When you compress it this way
you become more susceptible to signal loss from wave motion. You're tipping
the pattern away from the intended source. I'm no RF-weenie so forgive my
use of layman's terms.

The other downside to picking up distant signals is picking up TOO MANY
distant signals. Being able to grab a signal from a mile offshore is one
thing. But using that same setup while in an anchorage that has several
wireless networks will result in poorer network throughput. Higher power
sucks too, not just for you but for the other networks you're interferring
with.

After dealing with these issues for two seasons I decided it was a lot less
hassle to just get a cellular network data card. I pop the card into the
router and it's DONE. No fiddling, no leeching a wifi signal from someone's
unsecured network, etc. It "just works". I still have the wifi gear and in
the unlikely event I'm in an area not covered I'll certainly use it as a
fallback.

-Bill Kearney

On Wed, 2 Apr 2008 15:25:43 -0400, "Glenn Ashmore"
wrote:

By far the best solution is a waterproof wifi bridge at the masthead
connected by Ethernet with POE to a hub.

I thought I said that. :-)

I know it works for me.

"Glenn Ashmore" wrote in message
...
I think it would be wise to learn something about 2.4ghz wave propagation
and the Fresnel effect before you make that statement. If you just want a
couple of hundred yards range deck mounting is fine but for 2 miles plus
you need to be UP.

The maximum radius of the first Fresnel zone for 2 miles is 33 feet. So if
the tower is at 66 feet, the path is clear. Even if there was a large
reflection in the first zone, the maximum phase deviation would be 90
degrees, a phase quadrature signal, which would make the link even more
immune to fading and could increase the recieved signal strength as Wilbur
has reported.



By far the best solution is a waterproof wifi bridge at the masthead
connected by Ethernet with POE to a hub. Long range because there is
minimal coax loss and a wide Fresnel zone.

The Fresnel zone does not become any wider with that mounting installation,
it is just that there are less object to protrude into it.

The concept of a Fresnel zone is just a crude rule of thumb calculation to
prevent multipath. It doesn't take into account antenna beamwidth or any of
the physical properties of the in-path scatterers. It's great for
determining cell phone tower sites but is completely meaningless for
actually estimating what signals arrive at the antenna. You can place a
vertical aligned metal grid directly in the path of a horizontally polarized
signal and see virtually no effect yet the Fresnel rule of thumb would say
otherwise. The Fresnel rule of thumb sees no difference between vegetation
and buildings, it provides no insight into wave propagation at all.





--
Glenn Ashmore

" wrote in news:3fc8c447-
:

I am about to raise the new mizzen mast on my old Van de Stadt ketch
and I have been thinking about some other possible uses for the mast
head. Would it make sense to place a wi-fi antenna up there to make
better use of the hot spots that may be available in some communities?
Any suggestions for other hardware on the mizzen would be appreciated.
I am already putting a spare anchor light and VHF antenna, but I know
I will think of something else, when it is too late.
Tom


All these will be moot, soon. The big guns have endorsed and are paying
for Xohm.com's WiMax, this year.
http://www.xohm.com
http://www.wimax.com
http://www.dailywireless.org/2008/04/01/7607/
http://www.srtelecom.com/en/products...-LOS-and-NLOS-
Technology.pdf

Up until very recently, WiMax has been a bunch of little, unfunded
wannabees trying to hog the licenses for profit.....BUT, the BIG BOYS HAVE
ARRIVED!

Nokia, Samsung, Intel, Cisco.....

Wimax will have the range of PCS sellphones and the bandwidth of cable
internet....2 miles away from the nearest tower...not 100' from the marina
office. It hands off and roams like sellular data but without sharing
bandwidth with sellular voice customers. 2-4Mbps is realistic.

Xohm is Sprint/Nextel owned, at the moment, and will go up on all their
towers.....eventually.

BIG money is being poured into Xohm's WiMax now....

On Wed, 02 Apr 2008 06:41:59 +0000, Larry wrote:

BIG money is being poured into Xohm's WiMax now....

Maybe in 2 or 3 years. Meanwhile WiFi and/or Aircards are the way to
go. With the right equipment WiFi is operable up to 3 or 4 miles over
water.

I use a marinized version of: http://www.radiolabs.com/products/wireless/waverv.php
Over water I can 'hit' at 2+ miles

Amen to all the respondents about how wifi can work, and how long it
will be before the newer technology is available.

To shorten the learning curve, while I didn't do this (those here for
a while, and those visiting alt.internet.wireless, I think it was,
will recall I went through the tortures of the damned to get to where
I am today), my equivalent is available in 12V, plug-and-play, from
islandtimepc.com. Those interested can see all the installation
details, as well, in my photo gallery.

Bob Stewart, the owner, who's also, now, sold me the 12V replacement
to my rapaciously hungry (over 10A) "laptop", was extremely helpful in
assisting my way through the minefields that a senao rep had created
for me by selling me something which patently wouldn't work. The end
result was essentially what he sells, but I'd already done the 110VAC
POE, so didn't replace it. I heartily recommend him, unless you're a
geek like me and like tinkering, and would rather recreate the wheel.
In the end, I would have been far better served to have bought it
there, immediately, and I'd have had more than 2 additional years of
use, rather than the first two years of agony (and failure, along with
constantly having to defend my time to Lydia, who wanted everything
else to be done first - but, now, having internet phone and her own,
separate, wifi signal aboard, loves it and forgives me) I did...

As to strength and utility, it's now a very rare event that I don't
have a usable signal at anchor, anywhere, and frequently can pick up a
usable signal under way if I'm near (1-3 miles) shore...

L8R

Skip

Morgan 461 #2
SV Flying Pig KI4MPC
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