Method of tuning dipoles using capacitors and variable-capacitance diodes

A method of tuning dipoles using discrete capacitors is presented with a theoretical model and experimental verification. Two or more capacitors are placed at various points across the two wires of a folded dipole to cancel the reactive part of the driving-point impedance for single-frequency tuning. Variable-capacitance diodes can be used in place of the capacitors to tune a dipole over a very wide band of frequencies. These tuning techniques are demonstrated for a 7.5 cm monopole at frequencies from 500 to 1270 MHz. Methods are described and demonstrated for suppressing the harmonics which are intrinsically generated by the diodes.