New System for Measurement of Low Frequency Radio Transmitting Antenna Parametersin Near Real Time

摘要

Fixed site very low frequency (VLF) and low frequency (LF) transmit antennasystems are used as the primary means of communication to submarines at sea. Until now there has not been a system to measure important antenna parameters on these low frequency transmit antennas in near real time while the antenna is being driven by frequency shift modulation. This paper describes a new system which can be used to measure several important antenna and tuning system parameters on these transmit antennas while the antennas are in normal operation. The measurements are made by sampling and processing the antenna voltage and current signals to calculate the antenna system resistance, capacitance, inductance, voltage, current and power which can then be displayed and stored on a personal computer. All of these measurements are made while the antenna is being driven by FSK or MSK signals. The paper includes a model of a typical low frequency transmit antenna as well as the associated equations. The response of the antenna system to frequency shift keying signals is then presented. In addition, the algorithms, hardware, and software used by the measurement system, called the VLF/LF antenna monitor system (AMOS), are discussed along with a summary of results obtained during initial testing of the AMOS system.