This paper describes a nondestructive measurement method for complex permittivity of dielectric plates at 2 GHz, using a cylindrical cavity resonator. The resonator is divided into two parts at the center. Two dielectric plates are symmetrically loaded around the center of the cavity. These plates have high permittivity of 45. A dielectric plate specimen is clamped with these halves. The values of relative permittivity ε and loss tangent tanδ of the specimen are obtained from the resonant frequency and unloaded Q-value of TE011 mode. Measured results of various materials are compared with those values obtained at 3 and 10 GHz by other cavity resonator method. An edge effect is taken into account by a reference method, using measurement data of a sapphire plate. The errors of the present method are smaller than 1% and 2-310-5 for ε and tanδ, respectively.

Bifurcations of the periodic solutions of the space-clamped Hodgkin-Huxley equations for the muscle membrane are studied regarding the chloride conductance as a parameter. A limit cycle appears at a Hopf bifurcation and disappears at a homoclinic orbit. With high sodium permeability, a subcritical period doubling bifurcation occurs before it disappears.

A muscle membrane model (the same form as the Hodgkin-Huxley (H-H) equations for the squid axon) at low chloride conductance is shown to have a stable periodic solution, a stable equilibrium point and two unstable equilibrium points simultaneously. This structure does not appear in the H-H equations.