Fig. 4 Example of Voltage Probe Transmission Loss Measurement (Example of S21 Parameter MeasuringMethod)3.4 Measurement Box Antenna (For 30 MHz or less)A device to measure the radiated noise in the band of 30 MHz or less emitted from the specimen.Since the measuring box is the loop antenna type as shown in Fig. 5, it shall be installed on thenonconductive skid such as a wooden table to carry out measurement. The metallic table must notbe used as it will intercept electromagnetic wave, which is penetrating the loop antenna, in such a wayas to deteriorate the measuring value which leads to inaccurate measurement.(1) Dimensions: W500 D300 H200 mm(2) Material: Polystyrene foam or other material having relative permittivity of nearly 1.(3) Antenna: Wind two turns of AV wire or formal wire whose lead wire section is 1 mm diameteraround the box.(4) If the box it too small to accommodate the test specimen, the opening area W (mm) D (mm)may be increased. In such a case, however, the test data shall be determined by subtracting thecoefficient 20 Log10 [(W D) / (500 300)] (dB) from the actual measurement values.