Ghetto lightweight VTX antenna for micros

On my lightweight x2 EYAS (updated build link here) build I use an Eachine TX01 All In One (AIO) Camera/VTX. Stock, these come with a basic Circular Polarised (CP) antenna that works well but is heavy and more importantly: not very durable. This is because the antennas are left fairly exposed on micro quads.

More often now, AIO camera/VTX modules have linnear whip antennas that are much more durable, lighter and still get you about 90% of the performance of the CP antenna - much more practical in the real world for micro. Linnear whip antennas are actually a sleeved dipole where the outside sheild of the co-axial cable is grounded. The exposed centre transmitting signal is then exposed for a VERY specific length that should be tuned to 5.8GHz which in most cases is 12.9mm for a 1/4 wavelength of 5.8GHz.

Albert Kim did an excellent video here and found that most whip antennas have the wrong length. Great! Easy to cut if they are too long, hard to fix if they were too short. Well the 10 spares I had were too short!!

To fix this I tried the trick that my flysky FS82 and RX2a pro receivers use - a basic monopole antenna. This is a simple 28AWG wire (or any other small gauge wire) soldered directly to the signal line of the VTX with nothing on the ground pad. The wire is then cut to precisely 12.9mm, then heat shrunk over the top to relieve stress from the joint. Result:

• 0.8g lighter
• Video reception just as good as the dipole
• Even more durable antenna and less stress on PCB

What I see now is that the main reason for a dipole whip is to elevate the signal out of the frame where the AIO camera/vtx is enclosed. However, when the camera is mounted high like on my EYAS X2, it does not give any benefit and so the ghetto monopole antenna works just as well.

Relevant parts:

• Eachine TX01 25mW - AIO camera/vtx, comes with CP antenna
• Eachine TX05 25mW -  As above but pre-wired to work with betaflight OSD
• Spare pre-tinned whip antennas - if you want to use a dipole
• 28AWG silicon wire - if you want to use monopole
• LST S2 5.8G 800TVL HD Micro CMOS FPV Camera - AIO camera/vtx only 3.6g and handles light well for CMOS (cheaper presently than TX01 or TX05)

Quick follow up 10 months later and this continues to work well. I've now done the conversion to 4 AIO cameras with no ill effects. I've even done this on a FullSpeed tx200 piggyback vtx (review here) that is attached to the back of a runcam swift and no longer snag and lose the dipole. A really useful mod that has stood the test of time

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