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An analytic preconditioner for the electric field integral equation, based on the Calderon identities, is considered. It is shown, based on physical reasoning, that RWG elements are not suitable for discretizing the electric field integral operator appearing in the preconditioner. Instead, the geometrically dual basis functions proposed by Buffa and Christiansen are used. However, it is found that this preconditioner is vulnerable to roundoff errors at low frequencies. A loop/star decomposition of the Buffa-Christiansen basis functions is presented, along with numerical results demonstrating its effectiveness.