Re: Antenna array help!!!!
Hi, Shantanu:
I don't think there is any blocking. However, when two elements are close, the coupling always tries to suppress (or reduce) the radiation from the individual elements. You need fine tuning it in order to achieve best results.
Also, when two elements are close, it is not pure superposition. There is some interaction related to the correlation of the individual fields. If you look at the Poynting vector, you will see. Assuming antenna A1 is creating E1 and H1 and antenna A2 is creating E2 and H2 individually. The radiated powers are:
Pr1 = integral{ E1*Conj(H1) }
Pr2 = integral{ E2*Conj(H2) }
while their input powers are Pi1 and Pi2.
Assume you put them together and the coupling does not change the current distribution, you will have the input power as:
Pi = Pi1 + Pi2
However, the radiated power is:
Pr = integral{ (E1+E2)*Conj(H1+H2)}
= Pr1 + Pr2 + Pra1 + Pra2
Pra1 = integral{ E1 * Conj(H2) }
Pra2 = integral{ E2 * Conj(H1) }
If you further assume A1 and A2 are identical and they are moving to the same location, you will see, Pr1 = Pr2 = Pra1 = Pra2. In the other word, Pi = 2 * Pi1 while Pr = 4 Pr1. As you can see, the input power is doubled while the radiated power is quadrupled. Such a case is impossible. What it indicates is that when you put 2 elements close to each other, they will affect the current distribution of each other. If you still use superposition for such an analysis, you will over predict the radiated power. Certainly, when the coupling between the elements are far away, you can use superposition to get reasonable accurate results.
Best regards.