As a conductor’s diameter increases, what is the effect on its electrical length?

Explanation

Electrical length is measured against the current distribution standing on the conductor, and a thicker element spreads that current over a larger surface while presenting more fringing capacitance at its ends. Both effects make the current distribution complete its quarter cycle in less physical distance, so a given physical length corresponds to more electrical degrees and a fat element resonates lower than a thin one of the same size.