Difficulties in MoM analyses of resonant circular arrays of cylindrical dipoles

Previous studies have shown that a properly dimensioned, large circular array of cylindrical dipoles possesses very narrow resonances. Only one dipole is driven and the rest are parasitic. Those studies made use of the 'two-term theory'. In the present Letter, the Numerical Electromagnetics Code is applied to the aforementioned circular array. At some frequencies, meaningless results - large, negative driving-point conductances - are found. An attempt is made to explain why such results occur and to propose remedies when possible.