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Apr 20, 2011, 05:43 PM
Registered User
Old Man Mike's Avatar
Quote:
Originally Posted by Hugeone
Made one for 2.4ghz out of brass wire
Very nice. Do you have any SWR plots to compare with the model prediction?

Again, I want to say what an excellent job you did getting such a good Axial ratio with that design. Also, have you tried stacked set of two?

OMM
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Apr 20, 2011, 07:19 PM
Zephyr 66" Blunt
mark hitchman's Avatar
Quote:
Originally Posted by Hugeone
Made one for 2.4ghz out of brass wire
That is excellent workmanship, very nice.

Mark
Apr 20, 2011, 08:08 PM
Registered User
Hugeone's Avatar
Quote:
Very nice. Do you have any SWR plots to compare with the model prediction?

Again, I want to say what an excellent job you did getting such a good Axial ratio with that design. Also, have you tried stacked set of two?

OMM
Thx Mike

Unfortunately, I do not have access to an analyzer. I grant you permission to build one and test it I'll go for a "out in the field" approach...

I stacked them off course, gain is doubled but no more. It does not have the null on high/low horizon that your stack have.

-Hugo
Last edited by Hugeone; Apr 20, 2011 at 09:44 PM.
Apr 20, 2011, 09:21 PM
TBS Crossfire or DragonLink?
Hugeone....

Will your new antenna replace the CloverLeaf? a better/updated design?

Also, is your antenna more suitable for the VidTx ?
I'm using the Skewer Planar Wheel on the VidRX. (I'm using 5.8ghz 200mW VidTx from Foxtech and VidRX from Foxtech also).
Apr 21, 2011, 12:57 AM
Suspended Account
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Last edited by Mictronics; Jul 02, 2012 at 01:39 AM. Reason: Tired of RCG - Quality can be found at FVLAB
Apr 21, 2011, 01:52 AM
Registered User
Old Man Mike's Avatar
Quote:
Originally Posted by Mictronics
For now we have seen only real return loss plots but nothing about gain or radiation pattern. (apart from the simulation)

I would like to perform some measurements in this direction. At least for gain there are two methods: Two antennas where one has a known gain factor, or a second with three unknown but similar antennas.
I've been doing this for about a year using three receivers with 1 dB calibration matching of AGC output. It allows me to compare three receiving antennas directly during flight in an Excel format:



I can accurately compare RX performance averaged over selected periods of time such as at max distances or at specific elevations. Once again, NEC predictions always appear to correspond to real world measurements.

While flying, there is a real time bar graph showing the RX levels being collected. Notice in this 180 degree rotatation how the signal for all three receivers drop at the same time. This corresponds to the point where the quad body is directly between the quad antennas and RX base antennas:



By the way, it is not easy to maintain 1dB accuracy. I have to do a periodic calibration check and make sure that receivers are maintained at the same temperature (same warmup time, cooling, etc.). But the data collected certainly makes the effort worth while.

Quote:
Originally Posted by Mictronics
At work we have a standard gain horn for 1-1.7GHz. Since this is either vertical or horizontal polarization the question is, does it make sense to use it for gain measurements?

Can I just assume a 3dB loss due to polarization mismatch (to a CP antenna) and add this later on to the calculated gain?
The multipath will drive you crazy using this approach. Even CP to CP measurements are very inaccurate if you try to do it on a ground to ground setup. It really needs to be an Air to Ground measurement.

Quote:
Originally Posted by Mictronics
For the radiation pattern it might be useful if we don't use absolute values but draw the pattern just relative to the starting point.

Any other ideas?
I've often used the three receiver system to verify the elevation pattern. You need to use the GPS/baro for distance/altitude and then calculate the EL angle. The key is correlating the data time for position and the calibrated AGC levels.

OMM
Apr 21, 2011, 02:22 AM
Registered User
Hugo,
Can you give some dimensions for the 2.4GHz variety, I feel the urge to do something constructive over the easter holiday!

Thanks in advance and nice work, it certainly looks easier to construct than a SP.

Nigel.
Apr 21, 2011, 02:59 AM
Suspended Account
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Last edited by Mictronics; Jul 02, 2012 at 01:39 AM. Reason: Tired of RCG - Quality can be found at FVLAB
Apr 21, 2011, 06:51 AM
Engineer for Christ
IBCrazy's Avatar
Thread OP
Quote:
Originally Posted by LexusFPV
Hugeone....

Will your new antenna replace the CloverLeaf? a better/updated design?

Also, is your antenna more suitable for the VidTx ?
I'm using the Skewer Planar Wheel on the VidRX. (I'm using 5.8ghz 200mW VidTx from Foxtech and VidRX from Foxtech also).
This new antenna can be used as both a TX and RX antenna, just like the Skew-wheel and cloverleaf.

The testing I have done does seem to follow the simulation very closely. I think I am the only one who has used one of these so far.

I have not flown it on an airplane yet (RX antenna only) as the winds here have been in excess of 25 mph and it's a pain to land the plane. Once the winds die down, I'll fly my TX version.

-Alex
Apr 21, 2011, 02:29 PM
KF5LDN FPV Junkie!!!
Wizzard033's Avatar
Sorry for the off topic but has anyone ever experianced their VRx video fading after power up. The feed is good for a few seconds then it slowly fades

I bought a 900 VRx from New Generation and didn't use it for several months and once I did I found it didn't work.

Anyone know where I might search for an answer?
Apr 21, 2011, 02:44 PM
Registered User
Hugeone's Avatar

1280mhz


Made one for 1280mhz
Apr 22, 2011, 06:40 AM
Engineer for Christ
IBCrazy's Avatar
Thread OP
Quote:
Originally Posted by Wizzard033
Sorry for the off topic but has anyone ever experianced their VRx video fading after power up. The feed is good for a few seconds then it slowly fades

I bought a 900 VRx from New Generation and didn't use it for several months and once I did I found it didn't work.

Anyone know where I might search for an answer?
There is a 5V voltage regulator inside. It's a uA 7805 soldered flat to the board. You pin connections should read 5V, Ground, 12V. That would be my first suspected component.

-Alex
Apr 22, 2011, 12:41 PM
Internal Paradigm Consultant
perfeet's Avatar
Quote:
Originally Posted by Hugeone
Made one for 1280mhz
Looks nice, but it is big
Apr 24, 2011, 02:57 PM
KJ4IKY Gravity Wins
blade thrasher's Avatar
Quote:
Originally Posted by Hugeone
Look at this CP omni I made, a distant cousin of the SPW and easier to construct. I need a real-world test before making a "how-to".
Have no idea hake to interpret but would love a lesson.
Apr 24, 2011, 03:28 PM
Registered Loon
Blackrat's Avatar
got sizes for a 5.8ghz one please :-D


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