**Feels like an idiot...**

Okay guys, maybe you can help me out here.

I've got a 433 MHz signal and need to find a 50 Ohm antenna. Reliable sources tell me the length of this antenna should be 17.3 cm, but I just can't get it to work out.

Here's where I'm at: lamda=c/f = (300 * 10^6 m/s)/(433 * 10^6 s^-1) = 0.69 m = 69 cm

Now as far as I know, the length of the antenna should then be half of the wavelength to produce a 50 ohm impedance. 1/2 of 69 cm is NOT 17.3 cm.

Anyone wanna tell me where I'm going wrong?