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 Subject :VEHICLE MESH ANTENNA.. 2015-01-20- 01:20:18 
kc8rgo
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Joined: 2014-01-27- 20:44:36
Posts: 33
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What would be the groups recommendations on NMO antennas for MESH on board my vehicle - Toyota Sienna LE?  

I am finding them from $20 to $90.  I don't mind paying the price if the PRICE/PERFORMANCE is there.

I expect that I will use a UBNT Bullet in the van.

I expect that the 2.4 / 5.8 combos are a convenience compromise and that if I need to support 5.8 or 900MH a replacement antenna would be the best option.

Is a

L-Com HG2405UR-NMO 2.4 GHz 5 dBi worth the $90?

thanks - Vance - KC8RGO

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 Subject :Re:VEHICLE MESH ANTENNA.. 2015-01-20- 06:29:22 
K6AH
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Joined: 2012-03-05- 10:47:45
Posts: 181
Location: San Diego, CA

Vance,

Ubiquiti has a line of MIMO concurrently horizontal and vertical polarized antennas: http://dl.ubnt.com/datasheets/airmaxomni/amo_ds_web.pdf

These are likely the best choice... although they're expensive and require a Rocket rather than a Bullet because they need two RF chains to operate the two domains.

I have had good luck with the Bullet to an EnGenius 8 dBi vertical (model EAG-2408; $29) .  I operate this---while stationary---via a dash-mounted PC and wireless keyboard (see photos attached).  It works real well, but for best results, when at a distance of several miles, I need to respect the antenna's radiation pattern and position my vehicle below the node or on an incline facing the node. 

I would definitely mount the router on the roof directly connected to the antenna, not inside the vehicle as you've planned.  Note also, that the vehicles 12 volt battery is plenty adequate as a POE power source.

Andre, K6AH




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Last Edited On: 2015-01-20- 07:02:32 By K6AH for the Reason
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 Subject :Re:Re:VEHICLE MESH ANTENNA.. 2015-01-20- 07:18:34 
kc8rgo
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Joined: 2014-01-27- 20:44:36
Posts: 33
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Thanks, boy the $160+ prices sure slowed me down. May have to wait awhile.
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 Subject :Re:VEHICLE MESH ANTENNA.. 2015-01-20- 07:28:30 
K6AH
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Joined: 2012-03-05- 10:47:45
Posts: 181
Location: San Diego, CA

If and when you do get one, I'm sure this user community be eager to hear your thoughts on its performance.

Andre, K6AH

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 Subject :Re:Re:VEHICLE MESH ANTENNA.. 2015-01-21- 01:20:20 
kc8rgo
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Joined: 2014-01-27- 20:44:36
Posts: 33
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Trying to put light on some of the Presidents faces in my wallet - they kind of like the dark, but may be . . . . Need some help/opinion with antenna / equipment metrics: If I get the UBNT Rocket and the $160 10db antenna and use it for a central node, what is the relative strength of this central Rocket vs Nanostation M2 units in the field? i.e. communication needs to be two way. Will the directional pattern of the NSM2 have the same strength as the omni pattern of the Rocket when pointed at each other? SENIARO: I live on the Keweenaw Peninsula of Michigan which juts out into Lake Superior. For SAR and Events I want to cover a 60 by 20 mile rectangle with MESH. This is a relatively low noise environment. There are 30,000 people and several bear turds in the woods. I have access to towers at 10 to 20 mile distances down the center of this rectangle which could give be basic coverage and then deploy portable MESH nodes for fill for a Search or Event. WHAT is the infrastructure that should be deployed? Vance, KC8RGO

P.S. I guess I hijacked my topic here.

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Last Edited On: 2015-01-21- 01:22:53 By kc8rgo for the Reason Content not fully in topic.
 Subject :Re:VEHICLE MESH ANTENNA.. 2015-01-21- 03:43:55 
K6AH
Member
Joined: 2012-03-05- 10:47:45
Posts: 181
Location: San Diego, CA

This isn't an easy question to answer.  There are tools available, such as Radio Mobile (recommend the online version at http://www.cplus.org/rmw/rmonline.html), which will help you determine path feasibility, the power/antenna gain you'll need to make the distance, etc.  Many of us have successful links of 10 miles and some even 20 miles or more... but the devil is in the details.  I suspect you will not get 10 miles with a 10 dBi omni antenna and .4 watts unless the other end a dish with 20-30 dBi of gain range.  Rather, consider one or more sector antennas.  UBNT makes several of these as well.  Above all, the paths and their Fresnel Zones will need to be clear of vegetation.  You mention the area is forested.  This will kill 2.4 GHz and above.  You may want to consider 900 MHz if you have no choice but to shoot through vegetation.  But at 900 MHz you'll need to constrain the bandwidth to 5 MHz to respect other users and be careful to coordinate your channel with other local uses for the band.

So, as you can see, it's a complex question.  If you haven't already done so, I recommend to you and anyone planning a deployment to download and read Wireless Networking in the Developing World (http://wndw.net/). It'll give you all the background you'll need to successfully implement a mesh.

To answer the comparison question:

  • The Rocket TX power is 28 dBm and the vertical is 10 dBi for a total of 38 dB.
  • The NanoStation power is 28 dBm and the integrated antenna is 11 dBi for a total of 39 dB.

So they are equivalent within their antenna radiation patterns, but the Nanostation only has a 55 degree radiation pattern.

Remember that signal loss over distance follows the inverse-square law, so doubling the distance between nodes requires an additional 6 dB of power or antenna gain.  Achieving that 6 dB through antenna gain improves the link in both directions.  Achieving it with additional transmitter power only helps in that one direction.

Andre, K6AH

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Last Edited On: 2015-01-21- 05:49:27 By K6AH for the Reason
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 Subject :Re:Re:VEHICLE MESH ANTENNA.. 2015-01-21- 12:29:03 
AE6XE
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Joined: 2013-11-05- 00:09:51
Posts: 115
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Note that this 28dBm on the 2-channel ubnt devices seems to be split across the '2' antennas (vertical and horizontal polarization). Thus, the modeling of the path should use 25dBm (3dB less or half power split). I recently converted a Bullet M2 with 15dB omni to a Rocket M2 with dual channel sector 15dB panel. Consequently, I lost 3db of overall signal power per polarization, but other nodes can now connect with horizontal polarization in my saturated 2.4Ghz location. (Most people point antennas up to create competing vertical polarization signals.)
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 Subject :Re:VEHICLE MESH ANTENNA.. 2015-01-21- 23:23:31 
kc8rgo
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Joined: 2014-01-27- 20:44:36
Posts: 33
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Gentlemen, thank you very much for your help.  You are teaching an old dog new tricks :)  Your posts were very helpful to me.

I did read the book a year or so ago, and will be back into it.  The first pass was like being in a Cabelas catalogue where the items remembered were from the current hunting season.  With a bit more background and focus, I'm sure that a second read will help.  

Thanks again - What a MESH we have here. :)

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