For a helical antenna, the half-power beamwidth and directive gain are given by
where C = πD, N = L/S, and S = C tan α,in which α is called the pitch angle, and
The input impedance seen by the transmission line at point P is almost purely resistive, given by Za ∼ = 140C/λ. Calculate the antenna parameters of a 10-turn helix at f = 500 MHz by assuming that C = λ and α = 14π/180.