where array, k = 2Pi / wavelength , is the polar angle and is the difference of phase between any two successive elements forming the array.
The main objective of the tutorial below is to explore how each of the parameters N, d and affect the radiating pattern of the Interactive Tutorial
1 - Start the applet by clicking on the button "click here to start". On the left panel, you may use any of the sliders to change N the number of elements making the 3 - Set N = 10, d = 0.25 (this is 0.25*wavelength) and = kd = 2*Pi*0.25 = 0.5Pi. The main beam (maximum radiation) is directed toward = 180 degrees along the z axis which is also the axis of the array. If you change to -0.5Pi, the main beam is directed toward 0 degrees along the z axis. For these values of we have end-fire radiation.
Broadside
Array4 - Set N = 10, d = 0.25 (this 0.25*wavelength) and = 0 . The main beam (maximum radiation) is directed toward = 90 degrees normal to the z axis which is also the axis of the array. For this value of we have broadside radiation.
Change Phase For Scanning
5 - Set N = 10, d = 0.25 (this 0.25*wavelength) and change slowly starting from 0. Note that the direction of maximum radiation changes. The maximum radiation can be oriented in any direction. This is the basic principle of electronic scanning using antenna arrays.
More on antennas antennas and parabolic reflectors. |