The Field of a Dipole with a Tuned Parasite at Constant Power

Theoretical curves are shown of the electric field in the forward direction and in the backward direction for a center-driven half-wave dipole in the presence of a parallel center-tuned parasite of the same length and radius. The ratio of the electric field of the two-antenna array to the field of the driven unit alone at constant power is given as a function of the distance b between the antennas in the range from b = 0 to b = λ
0
, for both the forward direction (the parasite is a reflector) and the backward direction (the parasite is a director). The total reactance of the parasitic antenna is used as a parameter in the form X
22
= X
s2
+ X
2
where X
s2
= X
s1
, is the self-reactance of the parasite in the presence of the identical, driven dipole and X
2
is the tuning reactance at the center of the parasite. Values for which curves are shown are X
22
= 20, 10, 0, -10, -20 ohms and X
22
= X
s2
or X
2
= 0. Reactances and resistances used are those of the first-order King-Middleton-Tai theory.