Vertical and Horizontal Oriented Difference?

Hi,

I have the following 2 antennas:
Tunable dipole: tuned to 375MHz for my measuements
Broadband Dipole: 200-500MHz

I put the antennas in an anechoic chamber 3 meters from each other. First, I oriented both dipoles vertically and receiver -35dB in power on the network analyzer at 375MHz. Second, I oriented both dipoles horizontally and received -28dB in power.

Question: Why is there such a big difference of 7dB in power received? Shouldn't the power received be the same because both the antennas are positioned the same relative to each other?

Thanks

The reading should be the same so some other factor is present. My first guess would be the feeder is radiating/receiving, try rotating the feeder cables at both ends at the same time as the antenna and see it that is responsible.

Brian.

You cannot do this polarization test if the antenna height of both dipoles is less than 2λ (1.6m in your case).
For vertical polarization might be a challenge to reach this height in a normal chamber.
At these frequencies is better to do the test in open air using wooden antenna supports. And if is nice weather you can have a beer also