how to measure radiation Pattern....

dear all,

can any one help me to measure the radiation pattern of a horizontal polarized omnidirectional antenna. i have the radiation pattern test set up with me... i have some doubts..

1. A vertical polarized monopole antenna is mounted on a ground plane and connected vertically (azimuth plane / perpendicular to the ground) and the same is exited with a simple
log periodic antenna (as per fig 1).
Result: the pattern is omni-directional

2. The same antenna is mounted horizontally ( elevation plane / parallel to the ground) and the same is exited with a simple log periodic antenna (as per fig 2).
Result: the pattern is similar to "figure of 8"

3. Now i want to measure the azimuth radiation pattern of a horizontal polarized omni directional antenna. pls suggest me in azimuth plane & in elevation plane how to
fix the antenna? in which plane we will get omni patten? pls suggest which figure is azimuth? Pls seeFigure3 & 4

thanks for your time in advance

Biju

It seems to me that your problem is only the orientation of the antenna relative to ground.
An antenna has its pattern related to the "dipole" line like in Yagis, or, E or H if it has an aperture.

Azimuth and elevation are only related to the ground, and you should test your antenna in "any" plane, in a free space. The real pattern then indicates in which plane the antenna radiates omnidirectionally. Polarization of the reference antenna is also important in testing.