Everyone knows these small, nice, and recently in Germany allowed FM transmitter for MP3 player, which you can hear music in your car without cables. Unfortunately, the sound quality is due to permanent faults but very much to be desired. This is sometimes in the statutory, rather low transmission power. But you can improve a little bit, by pimps, the antenna a bit. For this I use an old and well proven principle of the antenna. In other words, just a cable in a certain length, which must be calculated beforehand. The best thing is when the length of the cable length frequency wavelength, or fractions thereof. The FM spectrum is in the VHF band II between 87.5-108 MHz, the mean count on us is thus 97.75 MHz.
Now we calculate:
Speed ​​of light [m / s] / frequency [1 / s] = wavelength [m]
in numbers:
300 million [m / s] / 97.75 million [1 / s] = approx 3.07 [m]
Since no one has fixed on a 3m long antenna, you can also use a fraction of them, eg 1/8 or 1/4. Ie 77 cm or 38 cm.

Then I have the body of my ultra-cheap, illegally produced in China by children, housing my FM transmitter and have opened the aerial search, which was glued a small strip of copper in the body. I have then extended the same time. At the point where it was soldered with a small antenna cables to the board, I then simply soldered on my 38cm cable. But the best thing now would be really, if we take this new antenna cable out of the case and simply hangs on the device, so the length to its best advantage. But I wound for aesthetic reasons, this cable and herded into the enclosure. Experimentally, I've also found that if I bridge the small SMD capacitor, which is located directly after the antenna connector on the motherboard, the range has again raised discreetly. Why can not explain it, maybe even one of my readers know the reason. Have fun listening to music!