marine antenna choices?

Are there other 2.4ghz antennae suitable for use marine use besides the 8db
unit from hyperlink?

I'd like to find one with a better vertical beam angle. Having only 15
degrees and then dealing with the rocking motion would end up making the
target area pretty small.

It'd have to be capable of being mounted in a ratcheting mount, to allow
getting under low bridges. The arch is about 9' above the waterline.

Thanks,
-Bill Kearney

"Bill Kearney" <(E-Mail Removed)> writes:
> Are there other 2.4ghz antennae suitable for use marine use besides the 8db
> unit from hyperlink?

If you want something with a wider vertical pattern why not just get a
5dbi rubber duckie? I doubt that such a small antenna will need to be
folded down for any bridge you'd really want to go under. ;-)

Mini-Box sells some $10 5.5dBi antennas that terminate in N-Male
connectors. The intension is that you screw them directly onto the
N-female on the outside of their weatherproof cast aluminum box. It
also looks like a nice way to mount an acess point outside. I'm
sorely tempted to pick up one of their boxes and antennas.

http://www.mini-box.com/s.nl/sc.8/category.19/.f

-wolfgang
--
Wolfgang S. Rupprecht http://www.wsrcc.com/wolfgang/

On Wed, 21 Jun 2006 13:58:21 -0400, "Bill Kearney"
<(E-Mail Removed)> wrote in
<(E-Mail Removed)> :

>Are there other 2.4ghz antennae suitable for use marine use besides the 8db
>unit from hyperlink?
>
>I'd like to find one with a better vertical beam angle. Having only 15
>degrees and then dealing with the rocking motion would end up making the
>target area pretty small.
>
>It'd have to be capable of being mounted in a ratcheting mount, to allow
>getting under low bridges. The arch is about 9' above the waterline.

See the Marine section of the Wi-Fi Wiki below.

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_How_To>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

> See the Marine section of the Wi-Fi Wiki below.

Which, informative as it may be otherwise, contains nothing of use in
answering my questions.

On Wed, 21 Jun 2006 13:58:21 -0400, "Bill Kearney"
<(E-Mail Removed)> wrote:

>Are there other 2.4ghz antennae suitable for use marine use besides the 8db
>unit from hyperlink?
>
>I'd like to find one with a better vertical beam angle. Having only 15
>degrees and then dealing with the rocking motion would end up making the
>target area pretty small.
>
>It'd have to be capable of being mounted in a ratcheting mount, to allow
>getting under low bridges. The arch is about 9' above the waterline.

Disclaimer: I've never done a marine wi-fi installation so much of the
following is speculation and guesswork. I did work for Intech
designing marine VHF, SSB, ADF radios, so I know a bit about vessel
installations.

Ever consider making a gimbal mount that maintains a vertical
orientation? Kinda like the gimbal rail mounts for keeping drinks
from sloshing. The truly sloppy way would be to just hang the 8dBi
omni antenna upside down from the flexible coax cable and let gravity
keep it vertical. A weight might be required at the antenna tip.
However, I suspect you might find this aesthetically disgusting and
want something a bit more elegant.

If you can find something with a ball and socket arrangement, the
antenna base can be screwed into the top of the ball, and a
counterweight screwed into the bottom of the ball. As the vessel
rolls with the waves, the antenna remains roughly vertical.

Instead of an omni antenna, I suggest something directional. For
example, the common build it thyself biquad antenna has a vertical and
horizontal beamwidth of about 60 degrees with about 9-10dBi gain.
http://802.11junk.com/jeffl/antennas/Biquad/index.html
You have to point the antenna at the access point, but then you can
swing and sway 30 degrees in any direction and it should still work.

One of my biquads was crammed into a 6" electrical box, which should
be sufficiently waterproof for marine use. I'm a fan of pressurized
boxes but I didn't do it for this package. Basic biquad construction:
http://homepages.ihug.co.nz/~redwood4/
http://martybugs.net/wireless/biquad/index.cgi
You might need to do some silver plating of the copper.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558 (E-Mail Removed)
# http://802.11junk.com (E-Mail Removed)
# http://www.LearnByDestroying.com AE6KS

On Wed, 21 Jun 2006 22:12:04 -0400, "Bill Kearney"
<(E-Mail Removed)> wrote in
<(E-Mail Removed)> :

>> See the Marine section of the Wi-Fi Wiki below.
>
>Which, informative as it may be otherwise, contains nothing of use in
>answering my questions.

I disagree.

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_How_To>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

> If you want something with a wider vertical pattern why not just get a
> 5dbi rubber duckie? I doubt that such a small antenna will need to be
> folded down for any bridge you'd really want to go under. ;-)

Yes, but I'm still faced with the challenge of getting it mounted.

I've got enough room inside the radar arch to put the router up there so my
RF cable lengths could remain quite short.

I'd consider using an N-female bulkhead socket if I could find an 8db (or
greater) antenna that would plug into it. That way I could have the short
5db unit plugged in 'most of the time' and only use an 8db stick when
needed. But I can't seem to find an 8db antenna with an N-male connector,
they all seem to have either a pigtail or an N-female on them.

Actually a plain bulkhead mount won't work as it can't adjust it's angle.
So I'd have to get some sort of adapter that'd let me use the antenna on a
regular ratcheting marine mount.

Although a bit of digging turns up some from Pacific Wireless. Anyone tried
them?

http://www.pacwireless.com/

> The intension is that you screw them directly onto the
> N-female on the outside of their weatherproof cast aluminum box.

I'd prefer something that looked good. This is a brand new 37' boat, I'm
not about to go bodging up some hack on it. I've got some dandy homemade
(metal mesh) parabolic screens setup on the home WiFi router and the wife
will have NONE of that on the new boat.

-Bill Kearney

> Ever consider making a gimbal mount that maintains a vertical
> orientation? Kinda like the gimbal rail mounts for keeping drinks
> from sloshing.

I don't need connectivity THAT bad <grin>. If it's rocking that much,
beyond what a 5db antenna might readily handle with a 15 to 30 degree
vertical beam, then I'm not likely to be getting much work done anyway.

But it does mean that using a flush bulkhead mount N-female will not be a
good idea. I wouldn't be able to change the angle enough to fine tune it's
alignment.

I'd like to find a way to use a ratcheting mount and also have the ability
to swap antennae. Most of what I'm seeing out there expects to use a
pigtail running through the socket or a pole mount. I've not yet found a
pole mount suitable. I'm open to suggestions on sources for one. The
problems being finding something that's going to be resistant enough to the
harshness of a marine setup (full sun exposure all day, salt water, etc).
Beyond just being resistant to the elements it's preferable to have
materials that won't cause discoloration of the surfaces under them should
they corrode or otherwise lose their finish. It's a white gelcoat on the
arch, stuff dripping makes things look ugly. Up on the roof of a building
you might not care, on a white boat you do.

That way I could open up the possible antenna choices to those using an
N-female on the bottom and run a small N-male to RP-TNC pigtail on the WiFI
device inside the arch (or nearby).

> However, I suspect you might find this aesthetically disgusting and
> want something a bit more elegant.

Yeah, I'd really like to keep it a clean-looking setup. For both aesthetic
and resale value reasons.

> Instead of an omni antenna, I suggest something directional.

For in-marina use, or when docked at a fixed pier that'd be workable. For
our home port, where I know the location fo the base station, it'd be great.
But when we're travelling I won't know where the base station is located and
I'm not sure I'd want to get into hunting for it. I'd rather just switch to
a higher gain omni and let it do the work. But then we're back to the
vertical beam issues. The further we are from the base, the wider the
vertical spread so (hopefully) it'd work.

> One of my biquads was crammed into a 6" electrical box, which should
> be sufficiently waterproof for marine use. I'm a fan of pressurized
> boxes but I didn't do it for this package. Basic biquad construction:
> http://homepages.ihug.co.nz/~redwood4/
> http://martybugs.net/wireless/biquad/index.cgi
> You might need to do some silver plating of the copper.

Impressive stuff, thanks for the links!

I'm now looking to find a suitable way to mount an N-female equipped antenna
onto a powerboat radar arch. Anyone know of suitable mounts? Or a way to
'cleanly' attach a pole antenna to a marine-style ratcheting base? The
ratcheting base is important not just for low-clearance situations but also
for changing the tilt.

-Bill Kearney

On Thu, 22 Jun 2006 03:12:43 GMT, Jeff Liebermann
<(E-Mail Removed)> wrote in
<(E-Mail Removed)>:

>Disclaimer: I've never done a marine wi-fi installation so much of the
>following is speculation and guesswork. I did work for Intech
>designing marine VHF, SSB, ADF radios, so I know a bit about vessel
>installations.

I have done a fair amount of marine Wi-Fi, and can also draw on the
experiences of other boaters I know.

>Ever consider making a gimbal mount that maintains a vertical
>orientation? Kinda like the gimbal rail mounts for keeping drinks
>from sloshing. The truly sloppy way would be to just hang the 8dBi
>omni antenna upside down from the flexible coax cable and let gravity
>keep it vertical. A weight might be required at the antenna tip.
>However, I suspect you might find this aesthetically disgusting and
>want something a bit more elegant.
>
>If you can find something with a ball and socket arrangement, the
>antenna base can be screwed into the top of the ball, and a
>counterweight screwed into the bottom of the ball. As the vessel
>rolls with the waves, the antenna remains roughly vertical.

It's probably not going to work very well without a really heavy weight,
low friction bearings (not just a simple ball and socket, and difficult
in an external marine environment), and serious damping -- otherwise it
will tend to get out of phase with the boat, and actually be worse than
a fixed mount.

>Instead of an omni antenna, I suggest something directional. For
>example, the common build it thyself biquad antenna has a vertical and
>horizontal beamwidth of about 60 degrees with about 9-10dBi gain.
> http://802.11junk.com/jeffl/antennas/Biquad/index.html
>You have to point the antenna at the access point, but then you can
>swing and sway 30 degrees in any direction and it should still work.

The problem I've seen with high-gain directional antennas, other than
mounting and aiming, is that they tend to be sensitive to boat movement,
even just small movements in a slip, resulting in wireless connections
that go in and out annoyingly. (I'm guessing there's considerable
multipath in many marinas.) I generally get the best results with
higher-gain omnis, mounted as high as possible.

I know of someone experimenting with a Hawking HWU8DD
<http://www.hawkingtech.com/products/productlist.php?CatID=32&FamID=60&ProdID=280>,
mounted with suction cups to a hatch, so he can set it up and remove it
easily. He says getting it aimed and keeping it aimed is sometimes a
hassle, and it's not good for a boat swinging at anchor, but is
otherwise pretty happy with it.

I've been surprised at how many Wi-Fi signals I see in many marinas.
Not only to many marinas provide Wi-Fi, often free, some boats are
offering free Wi-Fi to other boats in the marina.

The alternative to marine Wi-Fi is cellular data -- I sometimes get
better results that way, especially in remote anchorages. As in the
case of Wi-Fi, a good external antenna can help, although I've gotten
quite good results with my cell phone up on deck, with a laptop down
below connected to the cell phone via Bluetooth.

--
Best regards, FAQ for Wireless Internet: <http://Wireless.wikia.com>
John Navas FAQ for Wi-Fi: <http://wireless.wikia.com/wiki/Wi-Fi>
Wi-Fi How To: <http://wireless.wikia.com/wiki/Wi-Fi_How_To>
Fixes to Wi-Fi Problems: <http://wireless.wikia.com/wiki/Wi-Fi_Fixes>

"Bill Kearney" <(E-Mail Removed)> hath wroth:

>> Ever consider making a gimbal mount that maintains a vertical
>> orientation? Kinda like the gimbal rail mounts for keeping drinks
>> from sloshing.
>
>I don't need connectivity THAT bad <grin>.

Connectivity is currently the holy grail. The search for connectivity
has some similar characteristics.

>If it's rocking that much,
>beyond what a 5db antenna might readily handle with a 15 to 30 degree
>vertical beam, then I'm not likely to be getting much work done anyway.

Well, that means you can use a higher gain antenna. However, I was
more concerned about the pointing accuracy than the rocking motion. If
the marina access point is sufficiently close, almost any antenna will
work.

>But it does mean that using a flush bulkhead mount N-female will not be a
>good idea. I wouldn't be able to change the angle enough to fine tune it's
>alignment.

True. However, a short piece of LMR-400 coax between the antenna and
the N feedthrough bulkhead connector might be sufficiently flexible to
orient the antenna. What I'm concerned with is the omni radiationg
power in all manner of direction except the direction you want. That's
why I suggested a directional antenna.

>I'd like to find a way to use a ratcheting mount and also have the ability
>to swap antennae. Most of what I'm seeing out there expects to use a
>pigtail running through the socket or a pole mount. I've not yet found a
>pole mount suitable.

The typical marine antenna mount has a nifty lever for lowering the
antenna. However, adjusting it for vertical requires a wrench. There
is no fine adjustment as the meshing "teeth" are rather coase.

>I'm open to suggestions on sources for one. The
>problems being finding something that's going to be resistant enough to the
>harshness of a marine setup (full sun exposure all day, salt water, etc).
>Beyond just being resistant to the elements it's preferable to have
>materials that won't cause discoloration of the surfaces under them should
>they corrode or otherwise lose their finish. It's a white gelcoat on the
>arch, stuff dripping makes things look ugly. Up on the roof of a building
>you might not care, on a white boat you do.

Add UV embrittlement and not having accumulated salt jam the
mechanism. I could probably design a custom mount for the intended
purpose out of stainless. Unfortunately, I don't know of any existing
commerical product that will tilt, swivel, rotate, aim, and remain
vertical. I was thinking of modifying a motorized outdoor video
camera mounting and adding circuitry that would maintain a fixed
direction once set as stabilized by a solid state gyro. Something
like this camera:
| http://www.elmousa.com/cctv/pdfs/PTC_401CIP_Flyer.pdf
| http://www.2mcctv.com/product_info-S...pUSACPTZ1.html
| http://www.2mcctv.com/product_info-S...SAASH65NV.html
but without the camera.

Then, there's the manual version. See:
| http://www.ram-mount.com/camera_mount/camera_mounts.htm
Camera mounts. Some have knobs for easy adjustment. Install a
(white) plastic box with a biquad antenna inside on one of these.
Point it in the general direction of the access point. It's not
motorized or fancy, but it sure it cheap and easy.

>For in-marina use, or when docked at a fixed pier that'd be workable. For
>our home port, where I know the location fo the base station, it'd be great.
>But when we're travelling I won't know where the base station is located and
>I'm not sure I'd want to get into hunting for it.

It's worth the effort aiming the antenna. A few marina maps I've seen
show the exact location of the access points. You can probably get
the location by just asking.

Hunting is not that horrible. Most client radios have a signal
strength indication. They're not particularly responsive, so it won't
exactly be easy to adjust. If you were to use a 24dBi barbeque grill
dish antenna, with a 7 degree beamwidth, aiming will be almost
impossible. However, a 60 degree wide 9dBi biquad is very easy to
aim.

>I'd rather just switch to
>a higher gain omni and let it do the work. But then we're back to the
>vertical beam issues. The further we are from the base, the wider the
>vertical spread so (hopefully) it'd work.

The omni vertical beamwidth issue is a killer. It's so bad that it
even happens on vehicles. One mobile wi-fi user tells me that he had
to install a bubble level from a 4wd shop to make sure the antenna is
fairly level. Worse, some access points are overhead on light poles
and rooftops, which are impossible to "aim" the vehicle (short of
using a bumper jack).

Omni's also have a bigger problem. They pickup garbage from other
wi-fi users from all directions. In a marina, you're probably also
going to have reflection problems from masts and rigging. A
directional antenna will not eliminate these problems, but certainly
will reduce them dramatically.

>I'm now looking to find a suitable way to mount an N-female equipped antenna
>onto a powerboat radar arch. Anyone know of suitable mounts?

N to N bulkhead feedthough connector with a pair of drilled metal
plates (washers) on both sides for strengh.
| http://www.hyperlinktech.com/web/con...SKU=AXA-NFNFB2
The antenna screws into one side of the feedthrough. The coax cable
going to the radio into the other side.

--
Jeff Liebermann (E-Mail Removed)
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558