Rca1948FrequencyModu.. - The New Jersey Antique Radio Club

TURNSTILE ANTENNA 189This adjustment insured that the correct value of R was present foreach radiator. It should be noted that even though mutual impedancewas present between radiators, this method of adjustment takes accountof the mutual impedances without even measuring the specific values.We were now ready to adjust the series-inductance and seriescapacitancesections. The shorting straps were removed from theseries-inductance sections of the East and West radiators. The Northand South radiators were connected to the feed lines. The North andSouth radiator lengths and position of the shorting plugs were madeto correspond with the dimensions found to be desirable for the Eastand West radiators. Then, the approximate length for the seriescapacitancesections was calculated and the capacitance sections werecut a little longer than this length. The series inductance sections wereFig. 10—Arrangement used for adjusting the new turnstile antenna on theground.next adjusted by means of variable shorting-plugs until the main feedline was matched.Under this condition, the currents in the North and South radiatorswill be in quadrature with the currents in the East and Westradiators, but may be somewhat greater in magnitude than the latter.A field-intensity meter was placed a few hundred feet away from theantenna. The turnstile antenna was then rotated about the axis ofthe flagpole and observations of field intensity were made at the remotepoint. If the maximum field intensity was obtained when the Northand South radiators were pointing straight up and down, it was necessaryto shorten the capacitance sections to obtain a circular pattern.When the capacitance sections were shortened, the series-inductance