Modeling the electromagnetic radiation from electrically small table-top products

It is noted that the most difficult radiated electromagnetic interference (EMI) problems with table-top products often occur at frequencies where the maximum dimensions of the product are much smaller than a wavelength. Electrically small table-top products tend to be much more efficient radiation sources than dipole source models would predict, and the radiation is generally much more difficult to contain than other types of EMI source models indicated. The ways in which electrically small sources radiate are investigated, and a technique for modeling electrically small table-top products that have power or signal cables is proposed. The end-driven wire model is a strategy for reducing the product to a form that is more readily analyzed. The results is a relatively simple configuration that includes only those parameters of the product that are of primary importance to the radiated EMI calculation