Want to use circular parabolic dish for 802.11 wireless. What simple feed can I construct? Bi-quad looks easy. I've seen these used to feed a Primestar single-axis parabolic ( "trough" or "slot" reflector?). Is bi-quad also good to feed a circ. dish reflector?
Other ideas?
Thanks,
Dave, I just did at least .4 miles thru a pine tree with 50 % signal strength using a hawking54g with built in 6db antenna as the feed into a direct TV dish I found in the trash. The hawking is only $50 and all i did was tape the flat of the antenna down onto the orphaned dish amp feed so it was oriented properly with the sweet spot. the usb adapters also saves you the rf loss along the cable
I was testing with a laptop and the dish on top of my truck cab cradled by ladder racks -no real optimazation - closest house .3 according to odometer and development starts at .4 mile - I was able to pick up 4 signals by re-orienting slightly but only spent 10 minutes as I didn't want to attract unwanted attention doing this on side of the road. I am fairly certain I could approach 1 mile with proper mounting and orientation and likely twice that with a second dish at the source.
DaveC wrote:
Primestar
Biquad or Coffee Can feeds are fine. However, you must match your feeds illumination pattern with the f/D ratio of the dish. Each type of feed has a range of f/D dishes that will work efficiently. Start reading here:
The biquad was designed specifically for illuminating a Primestar offset feed dish with a f/D ratio of about 0.5 to 0.8 (depending on axis). See:
Lighting up deep dishes is a problem because the feed beamwidth needs to be rather wide. Biquads, cans, and dipoles don't do well. So, you'll see several "scalar rings" wrapped around a waveguide or can feed to widen the pattern.
If you're serious about designing and building your own, you might wanna try modelling your dish. See:
Also note that there's a legal power limit (FCC 15.247) when using high gain antennas (in the USA). An easy number to remember is 24dBi gain dish has a maximum allowable +24dBm (250mwatts) tx power for a point to point link at 2.4GHz.
Nope. You didn't bother to specify what you were trying to accomplish and what else you have to work with. Kinda hard to guess.
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