Patch Array?

sparafina · 06-06-2002

Had a brain wave while wearing my tinfoil hat (shiny side out of course).

It seems to me that patch and panel antennas are the easiest to build for the amount of gain, but they are too directional for stumbling. Then it hit me that cell towers used these in an array. So why not take 3-4 of them and combine them using a DSS splitter or one from a wireless CCTV system?

Would appreciate any input or suggestions, especially on calculating the placement or positioning. I've been looking at the Lindenblad construction, but I'm not sure its applicable. Also, what's the effect of using thinnet vs rg6/u (I probably should get some LMR, but I'm too cheap); and the effect of soldering the connections to the splitter vs using connectors to reduce loss.

blackwave · 06-06-2002

Quote:

Originally posted by sparafina
Had a brain wave while wearing my tinfoil hat (shiny side out of course).

I have been wondering about this as well, but don't have the time to research or fiddle. I would love to hear more about this.

lincomatic · 06-06-2002

that LMR stuff isn't really too expensive. u only need a few feet. even LMR400 is well under $1/ft.

lullabud · 06-06-2002

anybody ever try using buryflex? i had thought about buying some because it's cheaper than LMR, or was last time i checked. looks like it'd work fine...

lincomatic · 06-06-2002

comparing the specs between LMR400 the buryflex they seem very similar. same velocity factor 85%. the loss spec @ 400MHz is just a fraction of a db higher...but what's the buryflex loss @ 2.4GHz? anyway, @ $.59/ft it's the same price as LMR400

http://www.universal-radio.com/catalog/cable/coax.html

lullabud · 06-06-2002

i have no clue, it was just something i came across one day... but yeah, the price ain't competitive anymore. back when i found buryflex LMR was just under $1/ft.

Thorn · 06-06-2002

I have been told that the ideal lateral spacing between sector antennas is 10'. On that basis, I'm not sure that the plan is practical.

Day · 06-09-2002

As for a patch array, I was wondering the same thing so I ordered 2 of the 9.3dbi gain patch panels. Its not quite an array but similar idea.

First I have an older Toyota 4Runner so I mounted the panels one on each side. The panels work great! For driving they pretty much cover each side of the vehicle. I figured since I was going to be driving forward the majority of the networks would be on each side of the road =) - oh yea i'm using the cisco 350 card with dual mmcx connectors - anyway when I turned everything on I immediatly got 5 networks, turning the corner it jumped to 24. I have to turn the power down on the card so I can get acurate gps data and I'm not picking up an ap across the city but I'm more than impressed with the setup.

Driving to a point where I have an altitude advantage and can see large portions of the city I have great success as well (when i dont care bout the gps info). The setup is very neat and discreet, as everything is mounted inside the truck. I hope to post pics when I can find a dig camera - thanks for reading the long post

Day

"why are bunnies strife?"

lincomatic · 06-09-2002

sounds very interesting; by all means pls post the pics whun you gat a chance

Mother · 06-09-2002

The biggest problem with panel arrays is distortion of the signal arriving at the card due to time delays.

Basically, if you were to set up four panels, for example, you have to make sure that ALL of them are at the same distance, cablewise, from the card - otherwise you'd be causing multipath-like interference.

I remember helping out a friend who works for a local telco set up the antenna array of a TETRA station - they were having very bad problems with coverage in a particular area. After investigating, we found out that the cable running from one of the panels to the combiner cavities was slightly longer than the others.
This was causing the signal arriving at that panel to reach the combiner a bit later than the signal from the other panels, thus producing signal cancellation.

Cards which have diversity antenna inputs (i.e. two antenna connectors) will be able to compensate for this, but not as intended (to compensate multipath), but as a result of antenna placement.

If you were to place two antennas on each of the card's connectors, you should keep cable lengths the same, connectors really tidy, etc.

Cheers,

Mother

sparafina · 06-09-2002

Quote:

Originally posted by Mother
The biggest problem with panel arrays is distortion of the signal arriving at the card due to time delays.

If you were to place two antennas on each of the card's connectors, you should keep cable lengths the same, connectors really tidy, etc.

Yep, I've been doing some more research and looking at the literature from amateur satellites, tuning is crucial. I'll probably put this project on hold, until I understand microwaves and figure out how to test antennas.

06-06-2002	#1 (permalink)
sparafina Registered Member Join Date: May 2002 Location: TX,MD,NY Posts: 1,430	Patch Array? Had a brain wave while wearing my tinfoil hat (shiny side out of course). It seems to me that patch and panel antennas are the easiest to build for the amount of gain, but they are too directional for stumbling. Then it hit me that cell towers used these in an array. So why not take 3-4 of them and combine them using a DSS splitter or one from a wireless CCTV system? Would appreciate any input or suggestions, especially on calculating the placement or positioning. I've been looking at the Lindenblad construction, but I'm not sure its applicable. Also, what's the effect of using thinnet vs rg6/u (I probably should get some LMR, but I'm too cheap); and the effect of soldering the connections to the splitter vs using connectors to reduce loss.

06-06-2002	#3 (permalink)
lincomatic Squaaawk! WiFi! WiFi! Join Date: Apr 2002 Location: Tinsel Town Posts: 1,682	that LMR stuff isn't really too expensive. u only need a few feet. even LMR400 is well under $1/ft. __________________ ~lincomatic

06-06-2002	#5 (permalink)
lincomatic Squaaawk! WiFi! WiFi! Join Date: Apr 2002 Location: Tinsel Town Posts: 1,682	comparing the specs between LMR400 the buryflex they seem very similar. same velocity factor 85%. the loss spec @ 400MHz is just a fraction of a db higher...but what's the buryflex loss @ 2.4GHz? anyway, @ $.59/ft it's the same price as LMR400 http://www.universal-radio.com/catalog/cable/coax.html __________________ ~lincomatic

06-06-2002	#7 (permalink)
Thorn Did you do the math? Join Date: Apr 2002 Location: Villa Straylight Posts: 10,358	I have been told that the ideal lateral spacing between sector antennas is 10'. On that basis, I'm not sure that the plan is practical. __________________ Thorn "Read Altas Shrugged. Compare it to today. Repeat as necessary"

06-09-2002	#9 (permalink)
lincomatic Squaaawk! WiFi! WiFi! Join Date: Apr 2002 Location: Tinsel Town Posts: 1,682	sounds very interesting; by all means pls post the pics whun you gat a chance __________________ ~lincomatic

06-06-2002	#4 (permalink)
lullabud Registered Member Join Date: Apr 2002 Location: Silicon Valley Posts: 261	anybody ever try using buryflex? i had thought about buying some because it's cheaper than LMR, or was last time i checked. looks like it'd work fine...

06-06-2002	#6 (permalink)
lullabud Registered Member Join Date: Apr 2002 Location: Silicon Valley Posts: 261	i have no clue, it was just something i came across one day... but yeah, the price ain't competitive anymore. back when i found buryflex LMR was just under $1/ft.

06-09-2002	#8 (permalink)
Day Registered Member Join Date: Jun 2002 Posts: 8	As for a patch array, I was wondering the same thing so I ordered 2 of the 9.3dbi gain patch panels. Its not quite an array but similar idea. First I have an older Toyota 4Runner so I mounted the panels one on each side. The panels work great! For driving they pretty much cover each side of the vehicle. I figured since I was going to be driving forward the majority of the networks would be on each side of the road =) - oh yea i'm using the cisco 350 card with dual mmcx connectors - anyway when I turned everything on I immediatly got 5 networks, turning the corner it jumped to 24. I have to turn the power down on the card so I can get acurate gps data and I'm not picking up an ap across the city but I'm more than impressed with the setup. Driving to a point where I have an altitude advantage and can see large portions of the city I have great success as well (when i dont care bout the gps info). The setup is very neat and discreet, as everything is mounted inside the truck. I hope to post pics when I can find a dig camera - thanks for reading the long post Day "why are bunnies strife?"

06-09-2002	#10 (permalink)
Mother Too many secrets... Join Date: Apr 2002 Location: Barcelona, Spain Posts: 204	Diversity antennas The biggest problem with panel arrays is distortion of the signal arriving at the card due to time delays. Basically, if you were to set up four panels, for example, you have to make sure that ALL of them are at the same distance, cablewise, from the card - otherwise you'd be causing multipath-like interference. I remember helping out a friend who works for a local telco set up the antenna array of a TETRA station - they were having very bad problems with coverage in a particular area. After investigating, we found out that the cable running from one of the panels to the combiner cavities was slightly longer than the others. This was causing the signal arriving at that panel to reach the combiner a bit later than the signal from the other panels, thus producing signal cancellation. Cards which have diversity antenna inputs (i.e. two antenna connectors) will be able to compensate for this, but not as intended (to compensate multipath), but as a result of antenna placement. If you were to place two antennas on each of the card's connectors, you should keep cable lengths the same, connectors really tidy, etc. Cheers, Mother

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