Improved Calculation Method of Antenna in a Form of Open End of a Rectangular Waveguide with Partial Dielectric Filling and an Excitation Pin

Abstract

An improved methodology for calculating an antenna in the form of the open end of a rectangular waveguide with partial dielectric filling (PDF) and an excitation pin is introduced.An improvement in the antenna calculation method is provided by simultaneously taking into account the effective dielectric constant of a partial dielectric filling, changing the dimensions of the excitation pin and its displacement relative to the waveguide axis to reduce the geometric dimensions of the waveguide cross section and antenna matching in a certain frequency band enhancement. With this purpose, the value of the effective dielectric constant can be found through the intrinsic transverse vector functions of the hollow waveguide. In particular, the method provides an improved equation (9) to calculate the normalized conductivity of a coaxial waveguide transition from the side of a rectangular waveguide, which allows matching the excitation pin with the coaxial power line by determining (optimizing) its size and position in the waveguide. The obtained formula is used for normalized shunt conduction introduced by a resistance-loaded pin z1 and z2 , which may be applied in various certain cases when changing the nature of the load resistances z1 and z2 when calculating and designing other antennas and elements of microwave technology. The graphs of the dependences of the voltage standing wave ratio (VSWR) on the frequency for different radius, length of the excitation pin and its displacement relative to the axis of the rectangular waveguide are presented. With the optimal size and position of the excitation pin, the antenna matching in a certain frequency band is improved (the VSWR is reduced to a level not exceeding 1.18 in the 6-8 GHz frequency band).Also, the use of PDF allows to reduce the geometric dimensions of the cross section of the waveguide (up to 61% or more) without changing the electric size (for the 6–8 GHz frequency band the cross-sectional size of a rectangular waveguide for a wave H10 is 23 × 10 mm at a relative dielectric constant of plates thick cx =  6 mm, which equals to εr = 1,9). The charts of normalized antenna patterns in the E and H planes are presented. The reliability and validity of the results obtained is ensured by the convergence of the calculation results under boundary conditions with known results and the convergence of the formulas obtained in units of measurement.