24 Dbi parabolic grid in a neighborhood, distance?

cdaybox · 08-01-2002

Just making a rough estimate, how far would one say a 24 dbi parabolic grid could go in a decent sized neighborhood? I know you need to know what is in the way and such...but just assume you are using this antenna at your house, how far could it go? and the ap on the other side will be a standard linksys AP

bmoore314 · 08-01-2002

Hey my recent pictures help here.

Here is my dish network satelitte antenna:

http://www.forgottenfords.org/dishroof.jpg

its pointed at an ap through this:

http://www.forgottenfords.org/pointedat.jpg

The airport is a standard linksys, and is 2 blocks away.
across the street behind my house, and across the street behind that house, and at the other end of the block. My signal/noise ratio hangs aorund 10-14 db or so.

Brian

Thorn · 08-02-2002

Some people I know are running 20 miles or more with a 24dB dish.

For a "neighborhood" setup, why don't you use that 8dB omni you're selling? Unless you're doing a Point-to-Point and have the 24 already, it's overkill. Major overkill. On one of my setups we get 1.5 miles on a 4.5dBi omni. Another one I know of gets 7.65 miles on an 8dBi. At least I believe it is an 8. It is about the right size, but I haven't been up close to it.

Fritzo · 08-02-2002

So the 19db I just got for a house 500ft away was overkill? There's a tree in my line of sight, but it's pretty much a straight shot. I want to get 5-11MB if I can.

biko · 08-02-2002

how do you guys do that ?
i've tested my cantenna and I get about a gain of 15dbi.
but still i can't connect to an ap even one block away !!
is that possible or am i wrong somehow ?
I know that I have to aim my antenna, but it still doesn't work.
I live in a pretty dense neighborhood in boston.
thanks a lot
biko

lincomatic · 08-02-2002

Quote:

Originally posted by Fritzo
So the 19db I just got for a house 500ft away was overkill? There's a tree in my line of sight, but it's pretty much a straight shot. I want to get 5-11MB if I can.

maybe not if the tree has thick foliage. anyway, if you're just doing a point to point link the omni would also spread your signal further in all directions, making it easier for hackers to hook in.

Thorn · 08-02-2002

Quote:

Originally posted by Fritzo
So the 19db I just got for a house 500ft away was overkill? There's a tree in my line of sight, but it's pretty much a straight shot. I want to get 5-11MB if I can.

Fritzo,
That's definitely overkill. I'm serious. People I deal with are doing 20 miles with 24dBI at 11mbs.

Quote:

Originally posted by biko
how do you guys do that ?
i've tested my cantenna and I get about a gain of 15dbi.
but still i can't connect to an ap even one block away !!
is that possible or am i wrong somehow ?
I know that I have to aim my antenna, but it still doesn't work.
I live in a pretty dense neighborhood in boston.
thanks a lot
biko[/b]

The trick is to do the math. If it doesn't work on paper, it won't work in Real Life. Figure out your SOM, Frensel zone, and LOS.

BTW, where in Boston? I grew up win Roslindale and West Roxbury.

Quote:

Originally posted by lincomatic
maybe not if the tree has thick foliage. anyway, if you're just doing a point to point link the omni would also spread your signal further in all directions, making it easier for hackers to hook in.[/b]

True, but even a 19dB is a bit much. A 8dBi Yagi would probably do it. Maybe something on the order of a 14, but 19? The reason I suggested the 8dB omni is cdaybox has one already.

Thorn · 08-02-2002

Quote:

Originally posted by bmoore314
Hey my recent pictures help here.

Here is my dish network satelitte antenna:

http://www.forgottenfords.org/dishroof.jpg

its pointed at an ap through this:

http://www.forgottenfords.org/pointedat.jpg

The airport is a standard linksys, and is 2 blocks away.
across the street behind my house, and across the street behind that house, and at the other end of the block. My signal/noise ratio hangs aorund 10-14 db or so.

Brian

Brian,
Get a shorter and better cable, and you'll do a lot better. Suggestion: Put the AP in a weatherproof box, and mount it with the dish. Run Cat 5 to the computer, and run a short (6' for so) piece of LMR400 to the dish.

lincomatic · 08-02-2002

Quote:

Originally posted by Thorn
True, but even a 19dB is a bit much. A 8dBi Yagi would probably do it. Maybe something on the order of a 14, but 19? The reason I suggested the 8dB omni is cdaybox has one already.

agreed. i was just too lazy to mention using a lower-powered directional, esp since he already has the 19dB.

biko,
when you say you can't connect, are you sure it's because of signal strength? how many dB's are you showing for SNR/signal/noise?

btw, 15dBi is optimistic for a single-can cantenna. they are more like about 7dB or so.

cdaybox · 08-02-2002

I dont see how 24 dbi is overkill, there are networks in my area that from time to time show a small signal on my netstumbler and then go away, and i know that if i had 24 db I could get a nice signal from that AP

What is the best 24 db grid to buy? andrews? hyperlink?

Thorn · 08-02-2002

Quote:

Originally posted by cdaybox
I dont see how 24 dbi is overkill, there are networks in my area that from time to time show a small signal on my netstumbler and then go away, and i know that if i had 24 db I could get a nice signal from that AP

What is the best 24 db grid to buy? andrews? hyperlink?

The reason I say overkill is that they are essentailly made for long haul PtP. To use one to connect to a neighbor's house is like shooting flies with an elephant gun. Sure you can do it, but why would you? Better to do the math and work out a good system, than to spray excess RF where isn't needed.

Anyway, Andrews is a good brand. I've never used a Hyperlink.

bmoore314 · 08-02-2002

I cant have a shorter cable, the dish hooks to an orinoco card in a machine of mine, and I dont think I can put the machine outside. I most definately can get a better cable, right now its some generic type rg-8x that was cheap, and right now its only about 10 feet or so. If someone could donate an AP to a poor college kid, I'd be grateful

Brian

lincomatic · 08-02-2002

Quote:

Originally posted by bmoore314
I cant have a shorter cable, the dish hooks to an orinoco card in a machine of mine, and I dont think I can put the machine outside. I most definately can get a better cable, right now its some generic type rg-8x that was cheap, and right now its only about 10 feet or so. If someone could donate an AP to a poor college kid, I'd be grateful

Brian

maybe you should try that DWL900AP deal @ office max & cktsh*ty...$9 after rebate & price match if it works. also, did you ever get the biquad working? that will kick the can feed's butt on your dish.

bmoore314 · 08-04-2002

I have been really busy recently, havent worked much on antennas at all. My last project was a fan speed controller with a 555 doing PWM. Works well, took damn long to layout on a protoboard tho. Probably cause I never did it before

Brian

biko · 08-04-2002

The trick is to do the math. If it doesn't work on paper, it won't work in Real Life. Figure out your SOM, Frensel zone, and LOS.

BTW, where in Boston? I grew up win Roslindale and West Roxbury.

Thorn:
I live in Cambridge, close to Brattle Street in the Fresh Pond Area. I would really love to do the math, but how ? Do you have any good ideas about books or so...
Thanks a lot
biko

08-01-2002	#1 (permalink)
cdaybox Registered Member Join Date: Jul 2002 Posts: 49	24 Dbi parabolic grid in a neighborhood, distance? Just making a rough estimate, how far would one say a 24 dbi parabolic grid could go in a decent sized neighborhood? I know you need to know what is in the way and such...but just assume you are using this antenna at your house, how far could it go? and the ap on the other side will be a standard linksys AP __________________ f o r s h e e z y Last edited by cdaybox : 08-01-2002 at 01:56 PM.

08-02-2002	#3 (permalink)
Thorn Did you do the math? Join Date: Apr 2002 Location: Villa Straylight Posts: 10,430	Some people I know are running 20 miles or more with a 24dB dish. For a "neighborhood" setup, why don't you use that 8dB omni you're selling? Unless you're doing a Point-to-Point and have the 24 already, it's overkill. Major overkill. On one of my setups we get 1.5 miles on a 4.5dBi omni. Another one I know of gets 7.65 miles on an 8dBi. At least I believe it is an 8. It is about the right size, but I haven't been up close to it. __________________ Thorn "Read Altas Shrugged. Compare it to today. Repeat as necessary"

08-02-2002	#4 (permalink)
Fritzo Registered Member Join Date: Jun 2002 Posts: 8	So the 19db I just got for a house 500ft away was overkill? There's a tree in my line of sight, but it's pretty much a straight shot. I want to get 5-11MB if I can. __________________ Maybe in order to understand mankind, we have to look at the word itself: "Mankind". Basically, it's made up of two separate words - "mank" and "ind". What do these words mean ? It's a mystery, and that's why so is mankind.

08-02-2002	#5 (permalink)
biko Registered Member Join Date: Jul 2002 Location: Cambridge, MA Posts: 39	what am i doing wrong ? how do you guys do that ? i've tested my cantenna and I get about a gain of 15dbi. but still i can't connect to an ap even one block away !! is that possible or am i wrong somehow ? I know that I have to aim my antenna, but it still doesn't work. I live in a pretty dense neighborhood in boston. thanks a lot biko

08-02-2002	#10 (permalink)
cdaybox Registered Member Join Date: Jul 2002 Posts: 49	I dont see how 24 dbi is overkill, there are networks in my area that from time to time show a small signal on my netstumbler and then go away, and i know that if i had 24 db I could get a nice signal from that AP What is the best 24 db grid to buy? andrews? hyperlink? __________________ f o r s h e e z y

08-01-2002	#2 (permalink)
bmoore314 Stumbly Stumbly Join Date: Jun 2002 Location: south bay area, california Posts: 35	Hey my recent pictures help here. Here is my dish network satelitte antenna: http://www.forgottenfords.org/dishroof.jpg its pointed at an ap through this: http://www.forgottenfords.org/pointedat.jpg The airport is a standard linksys, and is 2 blocks away. across the street behind my house, and across the street behind that house, and at the other end of the block. My signal/noise ratio hangs aorund 10-14 db or so. Brian

08-02-2002	#12 (permalink)
bmoore314 Stumbly Stumbly Join Date: Jun 2002 Location: south bay area, california Posts: 35	I cant have a shorter cable, the dish hooks to an orinoco card in a machine of mine, and I dont think I can put the machine outside. I most definately can get a better cable, right now its some generic type rg-8x that was cheap, and right now its only about 10 feet or so. If someone could donate an AP to a poor college kid, I'd be grateful Brian

08-04-2002	#14 (permalink)
bmoore314 Stumbly Stumbly Join Date: Jun 2002 Location: south bay area, california Posts: 35	I have been really busy recently, havent worked much on antennas at all. My last project was a fan speed controller with a 555 doing PWM. Works well, took damn long to layout on a protoboard tho. Probably cause I never did it before Brian

08-04-2002	#15 (permalink)
biko Registered Member Join Date: Jul 2002 Location: Cambridge, MA Posts: 39	The trick is to do the math. If it doesn't work on paper, it won't work in Real Life. Figure out your SOM, Frensel zone, and LOS. BTW, where in Boston? I grew up win Roslindale and West Roxbury. Thorn: I live in Cambridge, close to Brattle Street in the Fresh Pond Area. I would really love to do the math, but how ? Do you have any good ideas about books or so... Thanks a lot biko

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