COMPARISON OF THE INPUT IMPEDANCE OF MONOPOLE ANTENNAS OBTAINED BY NEC, MINlNEC, AND MEASUREMENTS

Abstract

This paper compares the input impedance of monopole antennas numerically calculated by NEC and MININEC with experimental results. This comparison determines the limitation of these two computer codes used for modeling more complicated structures. Two groups of monopoles are considered. The first group consists of eight electrically thin monopoles of length .28 meters (.235 wavelengths at 252 MHz) and radii of .4064, . 7874, 1.168, 1.562, 2.390, 3.162, 6.350, and 7.920 millimeters (.341E-3, .661E-3, .981E-3, 1.31E-3, 2.01E-3, 2.66E-3, 5.33E-3, and 6.65E-3 wavelengths at 252 MHz). For this group, impedance calculations were compared to measurements over the band of 237-267 MHz. The second group consists of five electrically thick monopoles of length .2 wavelengths and radii of .0509, .0635, .0847, .1129, and .1270 wavelengths. For the second group impedance calculations were compared with measurements of tubular monopoles with flat ends. The results of this paper show that the extended kernel option of NEC predicted measured monopole impedance measurements more accurately than MININEC. [Vol. 10, No. 2 (1995), pp 75-85]