Characteristics of conical horns loaded with internal metallic discs

Horn antennas, pyramidal and conical, are extremely popular antennas at microwave and millimeterwave frequencies. Their widespread application stems from the simplicity of their construction, ease of excitation and large gain. However, they suffer from a number of deficiencies due to phenomena like spillover, phase error in the aperture field distribution or cross-polarization, resulting in reduced aperture efficiency of about 50% to 60% for optimum gain horn.