A question about the formula below which solvse the average characteristic impedance of a DIPOLE and is taken from page 7-12 of 23rd edition of ARRL Antenna Book. Q1.Is there an equivalent formula for a cubical quad element? Q2. Ditto for a wire skeleton saw-tooth element. Q3. Ditto for a wire skeleton rectangular element. To be used in a calculator for matching boom impedances of log periodic antennas with all four types of elements.