My Android phone (as many others) have FM radio receiver on-board. But apparently, it has no internal VHF antenna at all, since there is no signal at all w/o headphones plugged in and sound quality varies drastically depending on the headphone cable currently in place.
So, I'm curious how to build dedicated antenna, particularly, which pin(s) of 3.5mm connector FM receiver uses to get a signal from. Thanks!
Finally, found my worst headphones, less strong station and the longer conductor and did the clever experiment suggested by @Kevin again. However, I'm not exactly sure how to interpret the results:
With headphones connected reception improves when an additional conductor attached to all three pins (can't really hear the difference if any)
Without headphones (open circuit) I've got the definite results, reception have most clear treble frequencies at Tip pin (Left), noisy treble the Ring pin (Right) and the worst at Sleeve pin (Ground).