Q and Mu

Wheeler in 1947 developed fundamental limitations for antennas within a hypothetical cylinder using electrostatics and magnetostatics. Chu in 1948 derived fundamental limitations for antennas within a hypothetical sphere using exact electrodynamics. He used an iterative ladder network representing the antenna. After 58 years Thal in 2006 included energy inside the sphere, again using an iterative ladder network. As pointed out by Collin this is awkward for higher orders. Collin developed an exact closed form result, as Chu had done earlier, but in terms of spherical harmonics. He then developed the exact Thal results, again in spherical harmonics.