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Q: Long-range 802.11b Antennas ( Answered 5 out of 5 stars,   2 Comments )
Subject: Long-range 802.11b Antennas
Category: Computers > Wireless and Mobile
Asked by: apozniak-ga
List Price: $9.50
Posted: 31 Dec 2002 13:00 PST
Expires: 30 Jan 2003 13:00 PST
Question ID: 135664
I am looking for a long range 802.11b antenna that i can use easily
with little difficulty of setup that will extend a minimum of 3 miles.
I would like to find out where I can purchase something like that at a
relatively low price ($200-$400). I would also like some information
about how something like that works.

Clarification of Question by apozniak-ga on 31 Dec 2002 13:25 PST
I need an omni-directional antenna to BROADCAST a Cable Internet
Connection 3-6 miles. Basically I need the antenna to be like a
wireless access point. I will need to hook it into my router.
Subject: Re: Long-range 802.11b Antennas
Answered By: snapanswer-ga on 01 Jan 2003 10:39 PST
Rated:5 out of 5 stars
Below I have links to antennas in the price range you are looking for.
 In addition, I link to some helpful information about setting up long
range Wi-Fi networks.

In general, if you are trying to cover a 3-6 mile distance between two
points, you would use directional antennas to broadcast your long
distance, then omnidirectional antennas for client access points at
either end of the span.  If you are trying to blanket an area with 3-6
mile radius with access to your Wi-Fi network, you may need to create
multiple client access points throughout the area with omnidirectional
antennas.  The latter is similar to the goals of the Seattle Wireless
project, found with the links below.

I hope you find the information useful and easy to understand.  If you
have any questions about the information provided, please do not
hesitate to request a clarification.

Omnidirectional Antennas
Ramsey Electronics: DA25 Discone 450-2500Mhz Antenna Kit with

Ramsey Electronics: ISM9D - 6dBi 2.4Ghz Antenna 

Aerialix: ARLX-om2400-12 12dBi Omni Directional antenna
$100.00 assembled

Directional Point-To-Point Antennas
ISM19 - 19dBi Gain 2.4Ghz Antenna
$49.95  ($119.95 with 50 ohm feed)

ISM24 - 24dBi Gain 2.4Ghz Antenna
$59.95  ($129.95 with 50 ohm feed)

Pringle can 12db Yagi antenna

Additional Equipment
Logi/Yagi Equipment, Antennas, and Pigtails

Additional Information About Extended Wi-Fi Setup
TechTV: "Extend Your Wi-Fi Range" by Patrick Norton,24330,3306273,00.html

Seattle Wireless:  Questions About Nodes  2.4GHz Radio Resources

Search Strategy:  Review TechTV resources for Wi-fi
Search Terms:  Long range 802.11

Request for Answer Clarification by apozniak-ga on 02 Jan 2003 07:59 PST
I was wondering about dBi amount. Can you please explain the
approximate relationship of dBi with the actual distance (as in one
dBi=x feet). Thanks.

Request for Answer Clarification by apozniak-ga on 02 Jan 2003 08:09 PST
Also, I am interested in buying
with all options ($70) and was wondering what kind of dbi it has (not
listed) and the approximate range (whether or not it would get the 3-6
miles I need it to cover. Also if you could explain what the setup is
like (how to actually connect it to a broadband network) that would be
great, thanks.

Clarification of Answer by snapanswer-ga on 03 Jan 2003 01:20 PST
Thank you for the rating and the tip.  I am happy that you found the
answer useful.

I will try my best to add some additional details, though, I suspect
that the service staff at Fabcorp (listed below), Ramsey Electronics,
or Aerialix would have the most accurate information about what you
might expect for "real world" results.

The dbi relationship to distance is a tough one, because environmental
factors play a huge role in performance.  I can tell you that the
12dbi yagi antenna created from a Pringles can is expected to have a
point to point range of at least 10 miles.  However, an
omnidirectional antenna would not have nearly the same range at that
dbi.  For example, the description of the 6dbi omni antenna at Ramsey
Electronics suggests that they were able to get 11Mbps at 1/4 mile
with a hill blocking the line of sight.  From what I read, every 3dbi
is a doubling of gain.  If I surmise (perhaps incorrectly) that the
range approximately doubles as the gain doubles, than a 12dbi omni
antenna might be comfortable with a mile range in poor conditions,
further in good conditions.  Also, one might consider that at the
further distances, you may have a signal, but not one that can deliver
11Mbps.  However, you may find that even 2Mbps is adequate for many

You may want to reevaluate your choice of the DA25, because I believe
its specialty is reception rather than broadcast (I note that from the
way the description is written).  I suspect you will end up wanting
the highest dbi antenna that you can legally use under FCC
guidelines... which might lead you to the Aerialix or an even higher
gain antenna from another vendor.  Or, you may want to look at some of
the premade kits available affordably from Fabcorp:

In the case of the Fabcorp kits, you would simply connect the antenna
to the DLink or Linksys wireless router that you purchase separately. 
(Note that you want to keep the length of the wire from the wireless
router to the antenna as short as possible {less than five feet if
possible} to maintain signal strength).  You would connect your
Internet connection to the wireless router.

Since it sounds like you are planning to simply have one antenna
broadcast over a radius, that's it for setup.  You would then use you
wireless PDA or laptop and see what distance you can reach reliably.
(Depending on the environment and interference you encounter, you may
need to set up multiple antennas with overlapping radii to cover your
desired area.  I note in the material that typically point-to-point
antennas are used for reliable distances greater than 1/2 mile.)

You may find these links helpful in understanding the setup of this
type of network:
Range Extension Discussion:

FCC Limitations

Cityshare:  Sharing Internet Access Overview

Cityshare:  Simple Wireless Network (with Diagrams)

I hope that helps.
apozniak-ga rated this answer:5 out of 5 stars and gave an additional tip of: $1.00
Fast, accurate, better than I expected. Would Recommend!!

Subject: Re: Long-range 802.11b Antennas
From: snapanswer-ga on 31 Dec 2002 14:42 PST
Note to other researchers:  Most of the long-range 802.11b Antennas
I've seen with extended ranges are directional, meaning the broadcast
antenna needs to point directly at a receiving antenna.

However, if you find an omnidirectional antenna with that range at
that price, that would be a great find.
Subject: Re: Long-range 802.11b Antennas
From: loraan-ga on 10 Apr 2003 11:09 PDT
R.e. relationship of range to dBi:

The factor that's missing is input power.  Roughly speaking, the
relationship could be described as:

Transmit Power * dBi -> Range

Where "->" signifies "is proportional to".  That means that as
transmit power OR dBi (antenna gain) increases, range increases. 
Snapanswer-ga is correct that as gain doubles, range approximately
doubles.  As input power doubles, range approximately doubles as well.

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