Peaks and Nulls of Two Antenna

[Dan86]

Hi, relatively new to the forum so wondering if there is somebody who may be able to help.

I am doing a project where I am looking at setting up a measurement of the peaks and nulls of two antennas operating at 868 MHz, with one of the antennas being fed with the same signal amplitude but being approx. 90 degrees out of phase with the other.

Before I do this though I have been asked to determine this with calculations to see if the peaks and nulls that are calculated will then correlate to what I will then measure in a lab. The only thing here is I am not sure where to start as I jumped straight in looking at spherical co-ordinates with integrals etc. but was told to just look at the problem as two point sources and use basic trigonometry to work out the peaks and nulls and then to do some vector addition. Can somebody point me in the right direction of how to do this and if it can be done as simply as that without having to jump into high level mathematics?

 

[BradtheRad]

What pattern of ripples form on a pond when you toss in one stone, then toss in a second stone at a spot exactly 1/4 wavelength away?

This is similar to the pattern resulting when you overlap a:

a) sine curve (emanating from a point source)
and
b) cosine curve (emanating from a nearby point source).