Calorimetric Method for Measurement of Electrically Small Antennas Efficiency

To solve the problem of measuring the efficiency of electrically small portable and mobile antennas operating at HF and MF ranges, a calorimetric measurement method is considered. The method is based on the representation of the antenna as a physical system in which electromagnetic radiation is useful, and heat losses are detrimental. Measuring the heat loss of the antenna and its non-radiating equivalent allows you to estimate the efficiency. The description of the developed calorimetric installation for measuring the efficiency is given. Physical and technical features of its work are considered. For testing, a sample of a small-sized spiral antenna was selected, operating at a frequency of 1.9 MHz and matched with a 50 Ohm feedline with VSWR <; 1.1; the efficiency measurement was carried out, which showed the high efficiency of the antenna being measured.