Analysis and modeling of the input impedance of a short monopole antenna in the higt frequency band

Using impedance modeling of transmitter antennas based on reactance parameters measured with a vector network analyzer, an equivalent of a short monopole antenna operating in the 1.5-30 MHz range was developed, suitable for operation of the transmitting device. Equivalent circuit diagrams of the considered tri-band antenna and their parameters for high-frequency ranges of 1.5-6, 6-18, and 18-30 MHz are presented. To verify the adequacy of the equivalent circuits to the parameters of the real antenna, frequency dependencies of the real and imaginary parts of the impedance of the monopole antenna equivalent are shown, along with the corresponding equivalent parameters for the given ranges. The analysis revealed a noticeable deviation of the modeling results in the 18-30 MHz range compared to the real antenna, indicating the need for further refinement of the input impedance model for monopole antennas over a wide frequency range to improve its accuracy. The developed models enable the use of modern wideband matching theory tools for antenna matching.