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Old Jun 15, 2012, 03:22 PM
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Orlando, FL
Joined Oct 2004
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Question
What is the difference between these 2 antennas?

These came as a stock antenna in 900mhz VTx VRx units from two different vendors.
They all are referred as "Stock Antennas" but there's got to be a difference between them (other than the size of course). Both can be bent 90 degrees at any direction.

If you wouldn't mind sharing...
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Old Jun 15, 2012, 03:27 PM
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Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
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One is a base loaded 1/4 wave whip (has a little spring looking thing in the bottom).
The other is a 1/2 wave bazooka dipole.
The 2nd is likely a significantly better antenna, but you pay a significant weight/drag penalty.
Sometimes the whip will go as far as you need, although at 900Mhz they're notoriously bad.
Search for "modding junk 900Mhz antenna".

Personally, if I were ever to go back to 900Mhz, I'd just build myself a simple Vee.
That antenna has worked great for me on 1.3Ghz if using linear polarization.

The Rx antennas for 900Mhz are often a significant limiting factor. The LCOM 900Mhz patch
has an undersized ground plane. Should look into getting a biquad if you stick with
linear polarization, or a crosshair if you move to circular polarization.

ian
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Old Jun 15, 2012, 03:31 PM
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Canada, ON, Toronto
Joined Jan 2011
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Depending on the vendors, worst case scenario is they work the same. Best case scenario, the little whip is 3dbi and the bigger one is about 5dbi, which would be a noticeable difference.
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Old Jun 15, 2012, 03:40 PM
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Lakewood, Colorado
Joined Aug 2002
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Actually, there's no reason the big one should have higher gain. It's just a dipole rather
than a whip and doesn't appear to be more than twice as long. But with a real counterpoise it
should perform better.

ian
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Old Jun 15, 2012, 03:55 PM
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Orlando, FL
Joined Oct 2004
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Thanks. I don't have much FPV experience. I have yet to discover the range difference between these two antennas.

-I have heard of Cloverleaf antennas. Like the one on the left but with a spherical shaped wires on the top. I guess it is considered circular polarized. It wasn't very expensive. Is this better than the Vee style if I am wiling to switch to circular polarization?

-Could the above antennas be cross-used? Like one on the VTx and the other is on VRx?
If yes, would it matter which one is on the VTx?

-Daemon, you said "if you were ever to go back to 900Mz..." Did it not work for you? That's all I have unfortunately...
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Old Jun 15, 2012, 03:59 PM
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Orlando, FL
Joined Oct 2004
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Also is the one on right called "Rubber Duck" antenna? I found conflicting info on this. Some websites call both of them as "whip antenna".
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Old Jun 15, 2012, 04:27 PM
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Lakewood, Colorado
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A "Rubber Ducky" is actually a neither of the above. It's usually a short (1/4 wave or less)
base loaded antenna (sometimes the whole antenna is base loading, with no straight part)
enclosed in a flexible housing. Mostly commonly used on CBs and other handheld radios.
Some people mistakenly refer to the antenna on the right as a rubber ducky.

Generally you should expect extremely poor performance if you try to use either of those
antennas on the Rx side. Go with what I said above. If you stick with linear polarization,
then use a biquad on the Rx. If you move to CP, then use a crosshair on the Rx.
There's lots of threads here about antennas. It's a major key to success.
See the "How to be successful" sticky thread at the top of the forum, for more info.

I used to use 900Mhz but found it performed very poorly in urban or near urban areas
due to a lot of external interference. Worked fine in rural areas.

ian
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