First DIY UHF antenna

This is my first DIY antenna...
Actually... it's just some sort of ... "mess" production. I made it up out from zero knowledge in head.
I was planning to build a "上下 18 寸" antenna with this coaxial cable and 13A power cord. However, I was too smart to build an antenna with 1 wavelength. So, the VSWR in VHF side just fly high to 1:5. However surprisingly, the VSWR for UHF could be lowered to as low as 1:1.7. So I just move on with the antenna's shape, hoping that I can get a even better VSWR.

I ended up with rolling the two cables together and twisted it into somekind of awkward shape. This lowers the VSWR of UHF to <1:1.1 and <1:1.3 for VHF. The sensitivity is not really high for this.. how should I call it? coxical antenna?.. coxical antenna. As seen, it is not really big in size..

I'm now wondering if there will be any problem with this antenna, as you can see, high p.d. could be induced on the shield coil. (Brown: connected to centre core, green/yellow: connected to shield) Anyone knows if there is gonna be any potential risk in using THIS awkward antenna? You're welcome to leave me a comment.