AN IMPROVEMENT TO THE TRANSMISSION-LINE MODEL OF THE FOLDED DIPOLE

The transmission line method provides a computationally efficient technique for obtaining the input impedance of a folded dipole. The method is limited however to cases where the separation between the parallel wires of the folded dipole is less than 1/100th of a wavelength. The paper extends the use of the method to include folded dipoles with spacings less than 1/6th of a wavelength. This is achieved by using an extended equivalent length based on the inter-element spacing of the folded dipole. The physical length of the folded dipole is increased by an extension factor of 0.39 times the inter-element spacing. The factor is obtained by numerical experiments using the NEC2 method of moments program and this is also used to generate the comparative results.