In Calculation of equivalent self capacitance of Small Transmitting Loop I mentioned that (Straw 2007), The ARRL Antenna Book 21, gave an expression for equivalent self capacitance of a Small Transmitting Loop of one turn:

C=HD where C is in pF, D in cm, and H comes from a given table of length/diameter ratios from 0.1 to 1.0. ARRL cites (Medhurst 1947) for this expression. Medhurst’s work was for solenoids.

Values of the Constant H for Distributed Capacitance Length to Diameter Ratio H ===== ===== 0.10 0.96 0.15 0.79 0.20 0.78 0.25 0.64 0.30 0.60 0.35 0.57 0.40 0.54 0.50 0.50 1.00 0.46

A 1m diameter loop of 10mm diameter conductor has l/d=0.01, so it is not covered by the table, and you might form the view from the table that H tends to 1.0 or thereabouts as l/d approaches 0, but that is an extrapolation and dangerous. Continue reading Calculation of equivalent self capacitance of Small Transmitting Loop – ARRL