Study on the Design Problem for Constant Characteristic Impedance TEM Horn Antenna

TEM horn antenna with constant characteristic impedance(CCI TEM horn antenna) as one kind of ultra-wideband(UWB) antennas has been widely used.As the characteristic impedance of such antenna is a constant value along the axial direction,the reflection loss in the horn is very low.In order to elevate the CCI TEM horn antenna'Vpp(peak to peak value of the far-field pulse in the axial direction),the relationship between the Vpp and the aperture as well as characteristic impedance is analyzed by numerical simulations and experimental measurements.If the CCI TEM horn antenna is fed by a 50Ω coaxial cable and its length along the axial direction is a constant value,the maximum Vpp of such antenna can be reached with optimal apertures.Also,when optimal aperture is chosen for the antenna with different impedance values,the Vpp of such antenna with characteristic impedance 280Ω is the maximum.