Short Traveling Wave Antenna

Hi all,

I want to design a traveling wave antenna which is not longer than approximately one wavelength and shall operate at ca. 0.5 GHz. In my initial design, I used a straight microstrip line with a characteristic impedance of 50 Ohms which I fed at one side and which I terminated with a resistive 50 Ohm load at the other side. It worked well, except for the fact that very little power was radiated and most power was dissipated in the resistor.

Does anybody know a more efficient design which has a significant higher radiation efficiency than a straight microstrip line?