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Old Nov 04, 2012, 09:19 AM
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Quote:
Originally Posted by IBCrazy View Post
2-1/8" for 1280MHz
Ok, is that measuring both legs? Right?
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Old Nov 06, 2012, 02:36 AM
novian89
Indonesia, Jakarta
Joined Sep 2012
65 Posts
before i bought one becouse they are attracted by low price in my countries
cctv Spy Camera mini wireless INFRARED 1.2Ghz




Uploaded with ImageShack.us

the camera has build in antenna
what can be modified so that its antena can be greater distance
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Old Nov 06, 2012, 02:44 AM
novian89
Indonesia, Jakarta
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sorry double post
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Old Nov 06, 2012, 09:13 AM
Engineer for Christ
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Amherst, VA
Joined Jun 2006
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You are going to need to hack into that thing a little and access the output transistor. Where then antenna is soldered on, solder in a section of RG316 coaxial cable. Connect the shield to the neares ground. Now simply build the antenna on the other end.

-Alex
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Old Nov 06, 2012, 09:14 AM
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Quote:
Originally Posted by bolo1234 View Post
Ok, is that measuring both legs? Right?
Correct.
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Old Nov 26, 2012, 11:37 AM
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Anybody have any idea where I can get 4-conductor shielded cable (I need a small diameter outer casing - preferably less than 4mm)?


Nevermind - Using a USB cable
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Old Nov 28, 2012, 06:03 AM
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Hello Alex, I have just spent a few hours reading all the information in your blog, thank you so much for spending the time and effort to put it down in words. I have just ordered the goods to have a go at an inverted vee.

Thanks again. Angry
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Old Nov 28, 2012, 06:16 AM
Ed @ Experimental Airlines
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Joined Sep 2011
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Completely aside from fresnel zone considerations, is there a critical proximity of "parts" (Vtx, camera, battery, other wires, etc.) to the video transmitter antenna that will actually detune or otherwise suppress transmitted power?

I'm getting what I consider to be pretty dismal performance from a Lawmate 2.4GHz 500mW, seemingly with less influence than I would expect between stock omni, Vee, cloverleaf antennas, and corresponding antennas (plus tried a patch) on receiver. I have a pretty tight setup with a 6cm feedline (except stock antennas) direct to Vtx, with PSU and camera immediately adjacent to the Vtx, and main battery 15cm from that.

I'm on the verge of abandoning this concept, just looking for some information and affirmation. Or if it's something else, I'll keep searching. Thanks!
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Old Nov 28, 2012, 07:44 AM
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Quote:
Originally Posted by ExperimentalAir View Post
Completely aside from fresnel zone considerations, is there a critical proximity of "parts" (Vtx, camera, battery, other wires, etc.) to the video transmitter antenna that will actually detune or otherwise suppress transmitted power?

I'm getting what I consider to be pretty dismal performance from a Lawmate 2.4GHz 500mW, seemingly with less influence than I would expect between stock omni, Vee, cloverleaf antennas, and corresponding antennas (plus tried a patch) on receiver. I have a pretty tight setup with a 6cm feedline (except stock antennas) direct to Vtx, with PSU and camera immediately adjacent to the Vtx, and main battery 15cm from that.

I'm on the verge of abandoning this concept, just looking for some information and affirmation. Or if it's something else, I'll keep searching. Thanks!
Yes. Even moisture causes detuning of the antenna. The wider the antenna bandwidth, the less it affects performance. The Vee is a narrow band antenna and thus the effect of environment is relatively high compared to a closed loop design such as a folded dipole (hence why folded dipoles are used as feeders for Yagi antennas).

However, this is likely not the cause for poor performance. Poor performance lies in the ground station at least 90% of the time. Poor performance on the TX side is more or less limited to fresnel zone issues.

Let me explain what I mean. This flight is the raw footage from a .000125W system. That's 125 uW or 1/8th of 1mW! My transmit power is really cut down as I was using this as a test bed for my new "Pepperbox" antenna that is comng out very soon.

125uW test flight - 2250 feet (3 min 18 sec)


-Alex
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Old Nov 28, 2012, 06:22 PM
2Vision-Air
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Blainville, Quebec, Canada
Joined Aug 2009
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Alex, i need your help again master

I have a meeting this weekend and have no time to crimp and make a top quality antenna, i just want to do a fast inverted V,

I have welding wires left from the CP antenna project + old 2.4ghz antenna,

What i did is open the old antenna and unsolder the cylinder around the dipole, then cut it to keep the connector and solder 2 pieces of welding wires (that i will trim to 2.4)
Lookig at pictures, you think that method is okay ?

Thanks Alex !



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Old Nov 28, 2012, 07:31 PM
Engineer for Christ
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Looks good to me. Open your angle up to 120-135 degrees for best results.

-Alex
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Old Nov 29, 2012, 04:12 AM
2Vision-Air
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Blainville, Quebec, Canada
Joined Aug 2009
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Quote:
Originally Posted by IBCrazy View Post
Looks good to me. Open your angle up to 120-135 degrees for best results.

-Alex
Thank you Alex, the angle was not set yet.

Thanks for always helping out !
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Old Dec 16, 2012, 10:18 PM
Houston, we have a problem!
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Hello Alex and all, i know it has probably been posted before but i am reasonably new to this thread, but is there a calculator or formulas to calculate the length of the antenna elements for an inverted vee.

thanks angry
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Old Dec 17, 2012, 08:45 AM
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Hello again please disregard previous post found info on page
161. Thanks
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Old Jan 02, 2013, 06:26 PM
Houston, we have a problem!
Joined Aug 2012
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Hello Alex, first test flight of the home made inverted vee this morning, 2.6 klm faultless video all the way, (900mhz 500mw tx) could not be happier, had a little interference on the way back, (vee pointing to nose).

Thanks for your tutorials. Is there any real advantage to building a 2/3 vee? space is not a problem.

Thanks again, angry
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