24 Dbi parabolic grid in a neighborhood, distance? - Page 2

Thorn · 08-04-2002

biko,
A good place to start is the Calculations pages of www.ydi.com. They have good diagrams which explain a lot of the basics, as well as some of the more advanced ideas. Most, if not all, of the calculations have the actual formulas posted there, too. (Of course, you have the option of going about a mile and a half east and just grabbing an MIT geek to help.

)

biko · 08-05-2002

Thorn:
thanks a lot, good idea ! The funny thing is, that I am an MIT geek myself. Not geekish enough though...
So whenever you need some hints in Material Science, ask me.
Take care
biko

Thorn · 08-05-2002

Great! I'll know who to contact when I need ask about mixing concrete on my first tower... Or would that be more a Civil Engineering type?

Seriously though, about MIT; There's a Ham club there, I know they have swap meets almost every weekend. I'm sure someone would be able to point you in the right direction if you asked around. I think I've read something on the web recently about a wireless networking community starting at MIT, too.

Good luck.

mshimek · 08-05-2002

I get coordination notices everytime someone is building or changing their 6 Ghz microwave systems on our channels or next to our channels.
I just got one that details a system the Commonwealthe of Pennsylvania is building. One of the paths is 10.05 miles, using a 25 MW (14 dbm) transmitter, (a little less than a 30 MW Wi-Fi Card!), using a 42.1 DB gain 8 foot parabolic dish antenna, with a 1.2 degree beamwidth! Antennas at both ends of the path were at 130' above ground level. Bandwith on this path is 4 T-1's.
Longest path is 32.436 miles, using 29 DBm (.794 watts), 8' dishes and a bandwidth of a single T-3. Most of these systems are designed for "Five 9's" or 99.999% reliability. It's not the power, it's done mostly with antennas. How would you like to be 250' in the air trying to aim an antenna with less than 2 degrees of beamwith?

Thorn · 08-05-2002

Quote:

Originally posted by mshimek
... One of the paths is 10.05 miles, using a 25 MW (14 dbm) transmitter, (a little less than a 30 MW Wi-Fi Card!), using a 42.1 DB gain 8 foot parabolic dish antenna, with a 1.2 degree beamwidth! ... Bandwith on this path is 4 T-1's.
Longest path is 32.436 miles, using 29 DBm (.794 watts), 8' dishes and a bandwidth of a single T-3. ... It's not the power, it's done mostly with antennas. How would you like to be 250' in the air trying to aim an antenna with less than 2 degrees of beamwith?

Like you said, "It's not the power, it's done mostly with antennas.", but try and tell some of these guys that. Every other new guy seems to think they need to be transmitting in the kilowatt range before they can go two blocks.

My fear is that there may be repercussions on the ISM band as a whole rather that the idoits who are illegal. The satellite radio companies tried that last month.

As for aiming that, no thanks! I have a hard enough time up 75' with a 15 degree beamwidth. I don't know how those guys who climb 1000' towers do it.

08-04-2002	#16 (permalink)
Thorn Did you do the math? Join Date: Apr 2002 Location: Villa Straylight Posts: 10,430	biko, A good place to start is the Calculations pages of www.ydi.com. They have good diagrams which explain a lot of the basics, as well as some of the more advanced ideas. Most, if not all, of the calculations have the actual formulas posted there, too. (Of course, you have the option of going about a mile and a half east and just grabbing an MIT geek to help.) __________________ Thorn "Read Altas Shrugged. Compare it to today. Repeat as necessary"

08-05-2002	#18 (permalink)
Thorn Did you do the math? Join Date: Apr 2002 Location: Villa Straylight Posts: 10,430	Great! I'll know who to contact when I need ask about mixing concrete on my first tower... Or would that be more a Civil Engineering type? Seriously though, about MIT; There's a Ham club there, I know they have swap meets almost every weekend. I'm sure someone would be able to point you in the right direction if you asked around. I think I've read something on the web recently about a wireless networking community starting at MIT, too. Good luck. __________________ Thorn "Read Altas Shrugged. Compare it to today. Repeat as necessary"

08-05-2002	#19 (permalink)
mshimek Chile-Head Stumbler Join Date: Apr 2002 Location: Wi-Fi Wonderland Posts: 57	Microwave Paths I get coordination notices everytime someone is building or changing their 6 Ghz microwave systems on our channels or next to our channels. I just got one that details a system the Commonwealthe of Pennsylvania is building. One of the paths is 10.05 miles, using a 25 MW (14 dbm) transmitter, (a little less than a 30 MW Wi-Fi Card!), using a 42.1 DB gain 8 foot parabolic dish antenna, with a 1.2 degree beamwidth! Antennas at both ends of the path were at 130' above ground level. Bandwith on this path is 4 T-1's. Longest path is 32.436 miles, using 29 DBm (.794 watts), 8' dishes and a bandwidth of a single T-3. Most of these systems are designed for "Five 9's" or 99.999% reliability. It's not the power, it's done mostly with antennas. How would you like to be 250' in the air trying to aim an antenna with less than 2 degrees of beamwith?

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08-05-2002	#17 (permalink)
biko Registered Member Join Date: Jul 2002 Location: Cambridge, MA Posts: 39	Thorn: thanks a lot, good idea ! The funny thing is, that I am an MIT geek myself. Not geekish enough though... So whenever you need some hints in Material Science, ask me. Take care biko