# Half wave dipole with parasitic element, (Gain calculation)

good morning all,

I have difficulties to find the correct formula that allows me to calculate the gain of half wave dipole in parallel with another parasitic half wave dipole. I'm trying to calculate the gain(theta,phi) of this array for different distances bentween the two dipoles. If you have any interesting book or link that would be great.

$$G_f(\phi)\left[\frac{\mathrm{A}}{\mathrm{HW}}\right] = \sqrt{\frac{R_{11}+R_{1L}}{R_{11}+R_{1L}-\lvert Z^2_{12}/Z_{22}\lvert \cos(2\tau_m-\tau_2)}} \times \left( 1+\left\lvert \frac{Z_{12}}{Z_{22}}\right\lvert \frac{\zeta+d_r\cos\phi}{} \right)$$

• Figure frome John.D KRAUS's book (Antennas for all applications, 3rd edition, P477) – Tarik L Oct 7 at 14:33
• Does the graph illustrate the difference between the calculated results of the equations and NEC2 simulations? – Brian K1LI Oct 8 at 12:17
• Yes sir (freq=868MHz), and i'm looking if there is another formula ! – Tarik L Oct 9 at 11:14
• Hey Tarik, I tried to write the equation in MathJax. How did I do? I couldn't read a few of the subscripts. If I made any mistakes please let me know in the comments and I'll fix them, or edit the question if you want to fix them yourself. – rclocher3 Oct 13 at 19:48