SITE ATTENUATION MEASUREMENTS USING SHORTENED DIPOLE ANTENNAS

Use of a shortened dipole with its element length fixed at the 80-MHz resonator length or a half-wavelength is studied for the site-attenuat ion measurement of the interference-wave measurement field. Since this shortened dipole antenna is specified as the standard antenna for int erference wave measurement, the antenna factor and the impedance chara cteristics are investigated by numerical calculations and measurements . Next, in regard to the measurement of the site attenuation with this antenna, the theoretical values are derived by the method of moments. Further, actual measurement is carried out at three outdoor locations . It is confirmed that the obtained theoretical values agree well with the measured data. As a result, it is found that the theoretical valu es can be used sufficiently well as normalized values. Therefore, a me asurement method of the site attenuation using a shortened dipole has been established. It is found that the use of the shortened dipole is better in terms of measurement error and labor than the conventional h alf-wave dipole in site attenuation measurements at these frequencies. (C) 1998 Scripta Technica.