What Is Azimuth Fourier Transform in Signal Processing?

[chingkui]

I am reading something about Electromagnetic wave and Antenna, and come across some equations that the author says are "Azimuth Fourier Transform" and "Inverse Azimuth Fourier Transform". While I am somewhat familiar with Fourier Transform in the time/frequency domains, "Azimuth Fourier Transform" really is something I see the first time and I am not sure from the geometry why they are defined that way. Have anyone seen anything like this and can point me to some more detail information? Is it just a special case of Fourier Transform in the spatial domain rather in time domain?

 

[Karlisbad]

Perhaps the article you read is referring to calculating the Fourier transform in Polar coordinates.. instead of cartesian ones.