General formulas for calculating magnetic field at a receiving loop placed at an arbitrary position from a radiating loop in a shielded room

摘要

The standard magnetic field radiated by a small loop antenna is used for sensitivity testing of radio receivers. To avoid interference from external sources, the test is often carried out in a shielded room. A formula to obtain the intensity of the magnetic field at the receiving loop, when a small radiating loop antenna and the receiving loop antenna are placed at random locations in a shielded room, is derived. The convergence of the formula is analyzed. Using the formula, an equation is derived which expresses the shielded room error or the effect of the room on the standard magnetic field. The correlations between the calculated values of the error and the measured results are reported.