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.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

"Wilbur Hubbard" wrote in message
anews.com...

"Bob Crantz" wrote in message
...

"Wayne.B" wrote in message
...


The potential problem is
the long run of cable up the mast which will create a lot of signal
loss even with the very best LMR400 cable.

That cable has a loss of about 6 dB/100 ft at WiFi frequencies. A
colinear antenna can have gain way in excess of the loss and maintain an
isotropic pattern in the horizontal plane. Figure 50' of cable with 3 dB
of loss added to a 9 dB gain antenna is a net gain of 6 dB. It could work
out quite well. One has to consider the entire system, not just isolated
elements. This is a much cheaper and more reliable solution than an
active bridge up on the mast head.

Glory!


I have personal experience with respect to this topic. Putting a wi-fi
antenna at the masthead is the WRONG thing to do. You don't want it high
up. You want it low down. It gets better reception low. The signals seem
to be stronger low. Mount a good amplified antenna at deck level for the
best reception. No need to worry about long lengths of co-ax at all.

Here's a good antenna that works well and is priced reasonably.
http://www.radiolabs.com/products/wi...ne-antenna.php

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.

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

On Wed, 2 Apr 2008 15:37:08 -0400, "Wilbur Hubbard"
wrote:


"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.

All worked out for you he
http://www.cisco.com/en/US/products/...ence_list.html

(Eliminating a lot of BS)

Are you sure you are not related to Jax?

I am a sailor too. Been sailing for 40 odd years now but I specify and
install long distance WIFI links as part of the job I do to pay for my
sailing. A bit over 60 systems to date including an island wide network of
anchorage hot spots for a pay for use operation in the Caribbean and a
private 9.5 mile link between Red Hook, St. Thomas and Little Thatch Island
.. I get paid well and I don't get many complaints. I have some idea what I
am talking about and, after monitoring a number of your posts, I have
concluded that you sir have a mouth in dire need of a good treatment of
Preparation H.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com

"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

I use the WaveRV marine antenna. Near metro, etc. areas I can get
adequate 'signal' 2-3 miles off the NE US coast. I have it mounted on
the stern rail ... seems to work better there.

"RichH" wrote in message
...
I use the WaveRV marine antenna. Near metro, etc. areas I can get
adequate 'signal' 2-3 miles off the NE US coast. I have it mounted on
the stern rail ... seems to work better there.


Thank you for telling it like it is. Experience under actual sailing
conditions trumps armchair bull**** every time.

Wilbur Hubbard

In article s.com,
"Wilbur Hubbard" wrote:

"RichH" wrote in message
...
I use the WaveRV marine antenna. Near metro, etc. areas I can get
adequate 'signal' 2-3 miles off the NE US coast. I have it mounted on
the stern rail ... seems to work better there.


Thank you for telling it like it is. Experience under actual sailing
conditions trumps armchair bull**** every time.

Wilbur Hubbard

Willie, what you know about 2.4 Ghz RF Antenna Propagation and Path
Design, is smaller than you IQ, which you amply demonstrate every
time you post. Best you leave this to the folks, who actually have
Professional Experience, in the field......

"You" wrote in message
...
In article s.com,
"Wilbur Hubbard" wrote:

"RichH" wrote in message
...
I use the WaveRV marine antenna. Near metro, etc. areas I can get
adequate 'signal' 2-3 miles off the NE US coast. I have it mounted on
the stern rail ... seems to work better there.


Thank you for telling it like it is. Experience under actual sailing
conditions trumps armchair bull**** every time.

Wilbur Hubbard

Willie, what you know about 2.4 Ghz RF Antenna Propagation and Path
Design, is smaller than you IQ, which you amply demonstrate every
time you post. Best you leave this to the folks, who actually have
Professional Experience, in the field......

All you armchair 'experts' can run off at the mouth till the cows come home
but it proves nothing other than your heads are full of theoretical crap.
What matters is how things work on a sailboat in the real work-a-day world.

I sail. I've sailed most of my life and I know what works on a sailboat. I
have actual practical experience with wi-fi on a sailboat. I know of which I
speak. You theorists just spout lame ideas without ever having put them to
the test.


Wilbur Hubbard
(sending this e-mail via a pirate signal through the wi-fi matrix and 1/2
mile offshore with wi-fi omni antenna stuck out the main salon hatch a mere
four feet above the water. Signal strength 95%, Link Quality 97%)

"You" wrote in message
...


Willie, what you know about 2.4 Ghz RF Antenna Propagation and Path
Design, is smaller than you IQ, which you amply demonstrate every
time you post. Best you leave this to the folks, who actually have
Professional Experience, in the field......

You could start by using your Professional Experience and explaining what
Wilbur has done wrong and why what he observes cannot be happening. As to
any professed expertise on radio wave propagation all I've seen here are
antenna installers. I'm sure they are competent at installing antennas but I
really doubt they could make any accurate predictions of radio signal
propagation based upon what knowledge is required for installing antennas.
Thinking an antenna installer is expert on radio path propagation is like
thinking the person who drains the bedpan in the hospital is a doctor.

Even Wikipedia states:

http://en.wikipedia.org/wiki/Fresnel_zone

"If unobstructed, radio waves will travel in a straight line from the
transmitter to the receiver. But if there are obstacles near the path, the
radio waves reflecting off those objects may arrive out of phase with the
signals that travel directly and reduce the power of the received signal. On
the other hand, the reflection can enhance the power of the received signal
if the reflection and the direct signals arrive in phase. Sometimes this
results in the counterintuitive finding that reducing the height of an
antenna increases the S+N/N ratio.

Fresnel provided a means to calculate where the zones are where obstacles
will cause mostly in phase and mostly out of phase reflections between the
transmitter and the receiver. Obstacles in the first Fresnel will create
signals that will be 0 to 90 degrees out of phase, in the second zone they
will be 90 to 270 degrees out of phase, in third zone, they will be 270 to
450 degrees out of phase and so on. Odd numbered zones are constructive and
even numbered zones are destructive.[2]"



Please Note the following: "On the other hand, the reflection can enhance
the power of the received signal if the reflection and the direct signals
arrive in phase. Sometimes this results in the counterintuitive finding that
reducing the height of an antenna increases the S+N/N ratio"

Based upon your Professional Experience and all that you know about "2.4 Ghz
RF Antenna Propagation and Path Design" can you refute the above
statement? Did you get the part about "Odd numbered zones are constructive"?
That means they increase the received signal. By lowering his antenna he has
increased reflection in the first Fresnel Zone - "1" is an odd number the
last time I looked and his signal should increase.

If there is some new type of non-causal electromagnetics I'd love to hear
about it, so fill me in.

BTW "2.4 Ghz RF Antenna Propagation and Path Design" should be stated as
"2.4 GHz Radio Wave Propagation and Path Analysis". Antennas don't propagate
and paths are usually analyzed, not designed.

Wilbur's observations are supported by proven science.