why am i getting the complex values after applying the phased.Freespace object to the rectangular waveform ouput

I want to simulate a correlative interferometry algorithm in matlab to estimate Direction of Arrival for a rectangular radar wave form generated by phased.RectangularWaveform using array of antenna.To simulate this i need to measure the phase differences between all the antennas in an array.

1)How to measure the phase of a signal arriving at an antenna ??

2)After applying a phased.FreeSpace to the rectangular waveform ,why am i getting complex values ?? what is the relation between those complex values and the distance between source position and target position ??

If any body wants to see the code which i have written ,i will upload it here

Answer 1

[George]

Hi Ijjada,

To answer your questions:

1) You can use the phased.Collector to measure the phase of a signal in each antenna in an array arriving from certain direction(s). See the following documentation to learn more - https://www.mathworks.com/help/phased/ref/phased.collector-system-object.html

2) You see complex values after applying phased.FreeSpace because the phase of the signal changes as a function of distance travelled. The phase of the waveform should be something like 360*mod(distance,wavelength) / wavelength. So for e.g. the phase of a waveform that has travelled 1.5 wavelengths is 180 degrees.