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Old Jun 29, 2007, 02:06 PM
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WBFlyer's Avatar
Portland, OR
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need the best omni directional antenna for receiver

need the best for max signal. I use the future hobbies setup and need to know the connector type as well. I think I need a polorized patch possibly.
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Old Jun 29, 2007, 02:53 PM
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Quote:
Originally Posted by WBFlyer
need the best for max signal. I use the future hobbies setup and need to know the connector type as well. I think I need a polorized patch possibly.
Patch and omnidirectional are mutually exclusive.

Pete
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Old Jun 29, 2007, 03:39 PM
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somebody her said to get a polorized patch 3bdi or something and lay it on the ground flat.
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Old Jun 29, 2007, 06:07 PM
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Get this with a SMA male connector...Done!

http://sharperconcepts.zoovy.com/c=c.../YSC-HG2409PCR
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Old Jun 30, 2007, 03:01 AM
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perfect. thanks!
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Old Jun 30, 2007, 11:20 PM
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Quote:
Originally Posted by Wmacky
Get this with a SMA male connector...Done!

http://sharperconcepts.zoovy.com/c=c.../YSC-HG2409PCR
What's the diff between right-hand, left-hand, and plain circular polarization?
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Old Jul 05, 2007, 05:44 PM
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Circular has one of two possible directions (L or R hand) and the first two examples are merely specific about the direction.
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Old Jul 05, 2007, 06:31 PM
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Quote:
Originally Posted by MtnGoat
Circular has one of two possible directions (L or R hand) and the first two examples are merely specific about the direction.
Right. It should also be mentioned, however, that you can suffer a 3dB (or more) loss with mismatched polarity. In general, vertical to vertical and horizontal to horizontal are best. Circular with vertical is OK if you're alright with losing a bit of gain to pay for more consistency. In general you shouldn't mix LH with RH circular polarity, however it's not so much of an issue for us, since our Tx antennas are vertically polarized (again, generally).
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Old Jul 05, 2007, 07:32 PM
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Yup, cross polarizing circulars R to L or vice versa blows big time.

I used a circular polarity RX system for a bit (vertically polarized omni on plane) and liked the result, it was more stable at various aircraft attitudes compared to running Vpol Tx to Vpol Rx.

At 200mW output the 3db initial mismatch wasn't noticeable because the antenna I was using was an 8 dB unit to start with. In any event, since I wanted more solid performance with respect to aircraft attitude onboard a slope glider, I found it acceptable.

I didn't care for the pattern of the circ pol antenna I had however (I hate aiming antennas, this was a directional, 8db feed element from a dish antenna) so I got a wifi plus "Multipolarized" omni from work and that's been my standard.

I don't know what they're doing in there but it works at different angles better than the Vpol whip standard with any Rx and it doesn't have the initial cross pol loss the circular patch does.

It's very omni and doesn't care what angle the airplane is. I added a 12dB LNA with a 1.5dB noise figure, and an ISM band cavity filter to the receive chain...my 200 mW system now gets me way farther away than I'll ever need.

The antenna was a little spendy new, luckily we use them at work, I just fished one out of the dumpster and it was OK. Ditto for the LNA and filter, which are *real* spendy. Sometimes jobs are handy to have for more than one reason!

Wi FI plus omni

They also have a tiny thumb sized antenna for this band (they call it the Bullet), I have one in the lab but I've never tried it out.
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Old Jul 05, 2007, 09:13 PM
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Well this interests me.

I have placed an order with Future Hobbies which is in transit. I ordered the Diversity RX and Wade recomended getting two circular polarized patch antennae (left & right, which aren't on the FH website yet) over the standard linear ones. The circular polarized ones have a beam width of approz 65 degrees both vertical and horizontal, whereas the linear only have 35 degrees vertical.

Can someone explain the best way to set these up. I assume they would be best set apart (1 foot will probably be my set up), and aimed so they have a bit of overlap in their horizontal beam coverage. Is this right?

Also is it possible to use one standard dongle (is this a whip?) antenna and one patch?

I'm new to this and this is my first system and can't find much info on using 2 circular polarised antennae, so any advice would be great.

cheers

Andrew
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Old Jul 07, 2007, 10:24 AM
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Can no one help me here?

Don't mean to be pushy or anything.
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