Question 8.17: Find the current in one of the dipoles in an antenna array i...
Find the current in one of the dipoles in an antenna array if there is
(a) No mutual coupling between the dipoles.
(b) A mutual coupling between the dipoles.
The driving voltage is V_{1} = 100 V and the distance between the two half-wave dipoles is d = λ/2. Estimate the amplitude and the phase change.
(a) For the case with no mutual coupling, we can apply (8.70) with Z_{12} = 0. This results in
Z_{11}I_{1} + Z_{12} I_{2} = V_{1} \\Z_{21}I_{1} + Z_{22} I_{2}= 0 (8.70)
I_{1} = \frac{V_{1}}{Z_{11}} = 1.183 e^{-j30.17°} A(b) For the case with mutual coupling, we obtain from Figure 8-21 that Z_{12} = -12.5 – j29.9 Ω . The solution of (8.70) yields the current
I_{1} = 1.218 e^{-j21.80°} AThe amplitude of the input current changes slightly, while the change in phase is more significant.
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