Hi I am building an rf transmitter for a short range data link at 433MHZ and am almost done, but I would like to understand better exactly what I am seeing with regard to antenna performance.
All technical notes I have read recommend a 1/4 wave whip over ground plane as offering the best performance, statements like: "Best range is achieved with either a straight piece of wire, rod or PCB track @1/4 wavelength over a ground plane", I understand many factors effect performance however I have found that a "bent" 1/2 wavelength length of wire offers better performance.
If I use a 1/4 wavelength I need (due to case requirements) to have two 90 degree bends in it (feed -> up, across, up). If I use a 1/2 wavelength I need to run it once around the (plastic) case (feed -> up, around the case, up).
I hope this makes some sense, anyway I have found the 1/2 wave is less effected by polarisation and offers generally better performance. However while more ground plane may help a 1/4 wave it seems to hinder the 1/2 wave, I guess because it shields the loop around the case?