Comment Re:30$? (Score 1) 135
Another way to calculate this: Google "c/1.8GHz" and it'll give you the result in centimeters. Then just divide by two to get a half-wavelength dipole or divide by 4 to get a 1/4-wave ground plane length.
If you want a high-gain directional antenna for >1GHz you're probably best off with a dish, perhaps using a cantenna-like feed horn.