MicroStrip Balun for TEM Horn Antenna used in Level Measurement

Abstract. Localized time domain pulses can be used for non-contact and non-destructive measurement of liquid level in industrial applications. Due to its wider bandwidth and directional radiation pattern, Transverse Electromagnetic (TEM) horn antennas are well suited for target distance measurements. For balanced radiation over a larger bandwidth, a TEM horn antenna is fed using a wideband balun. The design and characterization of a Microstrip wideband balun are presented in this work. Exponentially tapered balun with varying width and spacing were studied using Finite Element Method (FEM) based electromagnetic (EM) solver, Ansys HFSS® for operation over 2-10 GHz. Designed balun w as manufactured and characterized using a vector network analyser. Simulation and experimental data indicated better than -10 dB S 11 and VSWR less than 1.5 for the exponentially tapered balun.

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