Can you help me roughly CALCULATE how to increase the range of my home
Internet wireless WiFi setup to a shed 300 feet away from my house?

Presently, I can walk about half the way through the wooded area to the
shed with my laptop in hand before I lose the connection to the PCMCIA
802.11b,g Linksys card. Basically I need to gain 150 feet in "range".

But how?

At the store, I immediately become confused as I try to compare $30 USD
omnidirectional antennas (D-Link ANT24-070) that boost "power" by a claimed
7 db; $50 USD directional corner antennas (Hawking HAI15SC) that claim 15
dbi (whatever a dBi is); and $150 USD 802.11N routers that claim to boost
omnidirectional "range" by 4x (Linksys WRT300N).

How does an omnidirectional 7 db or directional 15 dBi boost in "power"
equate to range?

Approximately how many decibels of (omnidirectional or directional) power
do I really need to boost my WiFi range from about 150 feet to the 300 feet
I need?

Looking up what a decibel is
(http://en.wikipedia.org/wiki/Decibel#Definition), I
calculate the D-Link ANT24-070 omnidirectional antenna gives me about 5
times the power (assuming 7 db = 10^7/10 ~= 5); but does this get me the
additional 150 feet of range to my shed?

Spending almost twice as much money on the Hawking HAI15SC directional
antenna gets me roughly 30 times the power (assuming 15 db = 10^15/10 ~=
32); but is that enough power to get me the range to my shed?

Indeed, is there some way to add a Hawking 15db antenna on the receiving
end to get 1,000 times the power (15 db + 15 db = 30 db = 10^30/10 ~=
1,000); but what would I hook the wire output from this receiving antenna
to in the shed (I can't hook it to the pcmcia card, can I)?

Given those db calculations, how do I compare the antenna options with
replacing my home 802.11b,g router with the 4X range $150 USD Linksys
802.11n WRT300N router and the required $120 USD Linksys WPC300N PCMCIA
card (assuming 6 db = 10^6/10)?Will this three-antenna 802.11n router be
forced to drop down to 1X speeds because inside my house my kid's laptops
will all be using 802.11b or 802.11g? Or can the router work on both
802.11g to one computer and on 802.11n to the other computer at the same
time?

I'm so confused!

All I want is to make a well-informed buying decision to increase my WiFi
range reliably to 300 feet to a known point.

Can you help me sort out all these very confusing variable (to me anyway)?
I have no training in electrical engineering; but I can google.

Thank you,
Beverly

On Tue, 04 Jul 2006 06:28:16 -0000, Dave Platt wrote:
Can you help me roughly CALCULATE how to increase the range of my home
Internet wireless WiFi setup from 150 feet to a shed 300 feet away?

Doubling the range requires 6 dB of additional gain from the antennas
at one end or the other.

Hi Dave,

First thank you for taking the time to help me and anyone who read this.
Second, I'm going to have to go slowly with you so I'll respond one by one.

Third, does your statement that 6 dB of gain equates to 2 times the range
mean that the "square root" of the power difference is my key to
calculating the range?

That is, is this range calculation from dB power roughly true (based on
what you said)?

6 dB = 10^(6/10) ~= 4X the power, where the square root of 4X equals a
doubling the range (assuming an omnidirectional antenna)?

Beverly

6 dB = 10^(6/10) ~= 4X the power, where the square root of 4X equals a
doubling the range (assuming an omnidirectional antenna)?

I'm hoping I can extrapolate from the above statement to calculate the dB
gain for the $150 Linksys WRT300N router which claims a 4X range
improvement (so I can compare the $50 antenna's effect with that of the
802.11n router).

Following your lead, the power improvement necessary for a 4X range
improvement is 4^2 = 16X power gain.

This 16X power gain then equates to about 12 dB (since 12 dB = 10^[12/10]
~= 16X power).

So, is it safe to calculate that the claimed 4X range improvement of the
Linksys WRT300N wireless broadband router can be compared to that of a 12
dB gain omnidirectional antenna?

Beverly

On Tue, 04 Jul 2006 06:28:16 -0000, Dave Platt wrote:
Can you help me roughly CALCULATE how to increase the range of my home
Internet wireless WiFi setup to a shed 300 feet away from my house?

dBi refers to gain relative to an "isotropic" antenna
dBd refers to gain relative to a half-wave dipole
dBi numbers are approximately 2 dB higher than dBd numbers,
for the same actual amount of gain.

Hi Dave,

Oh my. I guess the Hawking marketing folks were trying to trick me by
quoting a decibel number that was higher those I compared with.
15 dBi ~= 15 -2 ~= 13 dBd

That makes the $50 USD 15 dBi Hawking HAI15SC Hi_Gain Antenna drop down
from a gain of 32X power to only 20X power which gives me about a 4X range.

13 dBd = 10^(13/10) power ~= 20x power

Assuming the square of the power is the range, I get 4X range.
20^(1/2) ~= 4X range

Assuming my reliable range is 100 feet, that equates to 400 feet of range.
100 feet * 4 = 400 feet range

Interestingly, for comparison purposes, that is the SAME RANGE that the
much more expensive Linksys (Cisco) WRT300N router claims.

Do these calculations make sense?
Beverly

On Tue, 04 Jul 2006 06:28:16 -0000, Dave Platt wrote:
Can you help me roughly CALCULATE how to increase the range of my home
Internet wireless WiFi setup to a shed 300 feet away from my house?

3 dB of additional gain equates to twice the delivered power at a
specific range. Because power falls off in proportion to the square
of the distance, twice the power yields sqrt(2) or about 1.4 times the
range, all else being equal (which it often isn't).

6 dB of additional gain is four times the delivered power at a given
distance, or twice the range for the same amount of power.

So that I may compare the different options available at the store to me
for increasing my range, are these simplified calculations below correct?

a. 3 dBd additional gain = 10^(3/10) ~= 2x the delivered power
b. 2x power = 2^(1/2) effective range ~= 1.4X the range

b. 6 dBd additional gain = 10^(6/10) ~= 4x the delivered power
b. 4x power = 4^(1/2) effective range ~= 2X the range

Can someone let me know if these calculations are correct because that
helps me equate the different antennas and routers to the one measure I
desire, which is effective range in the area of 400 feet.

Beverly

On Tue, 04 Jul 2006 06:28:16 -0000, Dave Platt wrote:
There may be a cheaper way for you to get the gain you need, from your
existing equipment, without spending any money at all. It's possible
to fabricate a corner reflector, or (even better) a parabolic
reflector, out of material as inexpensive as cardboard (or posterboard
or something like that) lined with aluminum foil. Simply make one,
and then set it behind your existing router's vertical antenna... aim
the parabola in the direction of your shed and place the router's
antenna at the focal point of the parabola. Aim carefully, and it
wouldn't be surprising for you to get 8 - 10 dB of additional gain.

Hmm. I wonder. This is too good to be true. So, I will be a bit critical
with you (i.e., the scientific method) just to "test" the assumption so
that I can be sure I understand your position.

Assuming a 9 dBd increase in the directional gain from putting a pie tin
behind one of my existing router antennas, that equates to either 280 or
380 feet of range based on the calculations below.

a) 9 dBd = 10^(9/10) power gain ~= 8x power gain
b) 8x power gain = sqrt(8) range gain ~= 2.8X range gain
c) 100 foot range * 2.8 ~= 280 foot range

I'm a bit confused about the "range gain". May I ask if thta 280 foot range
is the total range or the range improvement?

That is, is my range with a pie tin behind the antenna 280 feet in toto; or
is the range now the 100 original feet + 280 additional feet which equals
380 feet in toto?

Beverly

On Tue, 4 Jul 2006 11:03:49 -0400, Peter Pan wrote:
Can you help me roughly CALCULATE how to increase the range of my
home Internet wireless WiFi setup to a shed 300 feet away
....
I Had a linksys WRT54G in the house attached to my sat,
and used one of the 4 router outputs to daisy chain one to the wan input of
another WRT54G (same ssid) and a semi-directional antenna pointed towards
the garage about 500ft away,

Hi Peter Pan,

Oh my! Is "wireless" daisy chaining workable? Is it that easy?

I did not think I could just daisy chain multiple routers! Are you sure?
(My shed has no power but I think I could run an extension cord into it if
that would make things workable.)

Would I just set the second Linksys router (which, amazingly, has it's own
wikipedia entry at http://en.wikipedia.org/wiki/WRT54G) in the shed on the
same channel (SSID=12, name = default) as the first router in the house?

That is, could I put one linksys WRT54G in the house (perhaps with one
antenna replaced with a 7 dBd higher-gain directional antenna); and then
put the other Linksys WRT54G in the shed 300 feet away (perhaps with one of
it's antennas replaced with a similar 7 dBd directional antenna)?

Or, is it best to hardwire with cat5 the first router downstairs in the
house to the second router, say upstairs in the attic window pointing the
antenna toward the shed? I didn't even know that two routers could be daisy
chained. That might solve my dilemma.

Can someone confirm that two routers could be daisy chained either by wire
cat5 cable or by wireless signals as long as they use the same SSID channel
and network name? That solution seems to easy to be true ...

Beverly

On Tue, 04 Jul 2006 06:11:27 -0700, Dan Richardsonk6mhe wrote:
If your goal is to increase your range then add an extender
(hams would prefer to call them repeaters).

Oh my. The seemingly perfect option.

I had come across the concept of wireless "repeaters" in my initial
googling before I went to the store, e.g., in this Microsoft "how to
increase range" article
http://www.microsoft.com/athome/more...elesstips.mspx and in this
"Extending WLAN Range" article
http://www.wi-fiplanet.com/tutorials...le.php/1571601

The repeater most often recommended was the "Linksys Wireless-G Range
Expander WRE54G".

However, I can't find that 802.11b,g WiFi repeater (aka range expander or
extender) anywhere in the local stores. The salesperson who sold me the
$300 USD 802.11n router and PCMCIA card combination said they didn't work
so they dropped it.

This solution seems to be the most elegant of all (but someone else
suggested just using a second router).

Can someone unconfusify the situation?

Is placing a repeater (on the same SSID) in the shed really the same as
adding a second router instead?

Beverly

On Tue, 04 Jul 2006 17:57:22 GMT, stephen wrote:
but - you mentioned you could run power out to your shed. Why not plumb it
in for power and networking?
then you can add a separate access point there and avoid antennae, gain,
loss through leaves and the rest.

Hi Stephen,
I'm confused about this "access point" thing.

Is that the same as a "router"?

Is it as simple as buying a second router (routers are familiar to me) and
just hooking that second router to the first router by cable and that would
extend my range by the distance of the cable connecting the two routers?

This is a key confusion point for me!
Beverly

Beverly Erlebacher wrote:
I'm confused about this "access point" thing.

An access point is a device with an ethernet port on one side and a wifi
port on the other. In technical terms it would be called a "bridge". It
"bridges" two seperate network segments, although in this case they use
different topologies (100Base-T and WiFi).

Is that the same as a "router"?


The usual WiFi router consists of a four port ethernet hub (LAN ports),
a seperate single ethernet port (WAN port) and a WiFi access point.
It is set up to "route" between the single (aka WAN) port and the other
two ports, the LAN and WiFi. Most of what it does for routing is NAT (network
address translation) and some sort of IP tunneling.

If you ignore the WAN port and just use the LAN ports, you have a four port
hub and an access point.


Is it as simple as buying a second router (routers are familiar to me) and
just hooking that second router to the first router by cable and that would
extend my range by the distance of the cable connecting the two routers?

Yes. Just make sure to use the LAN ports. It would be best to use different
channels. Most WiFi clients are smart enough to use the channel that is the
strongest if they have access points on more than one with the same SSID.

Make sure to use encryption. Encryption is NOT to keep your data safe,
nothing can do that. If someone is intent on accessing your network, WEP
encryption will not keep them out.

What it is for is to convince the guy driving down the street looking for an
open network to send out SPAM, or "share" kiddie porn, to drive on.
Unfortunately, most users don't even change the SSID of their network, let
alone set an encryption key.

Having tuned in late, if you want to have an open network, look up PublicIP.
It's a "live cd" that runs on a PII or better (x86) computer and provides
all the functions you need to offer a secure and safe open network.

Geoff.

--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
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