In either case, one obtains the following expression for the minimum value of Q in (19) for a highly dispersive lossy electric and magnetic dipole antenna
Consequently, the minimum value of Q in (19) for a nondispersive-conductivity electric and magnetic dipole antenna with [mathematical expression not reproducible] is
The quasi-static electric-dipole electric field [E.sub.e] of an electrically small electric and magnetic dipole antenna dominates the electric field both inside and outside the surface [S.sub.a] of the antenna [V.sub.a].
The magnetic-dipole magnetic field [H.sub.m] of an electrically small electric and magnetic dipole antenna dominates the magnetic field both inside and outside the surface [S.sub.a] of the antenna [V.sub.a].
Also, Thal  has obtained lower bounds on the Q of spherical electric and magnetic dipole antennas under subsidiary conditions that maximize the gain of the antenna and increase the lower bounds by requiring extra internal tuning to maintain the proper phase between the single-port electric currents that feed the electric and magnetic dipoles.
Similar to the principles found in seismic systems, the RIM-IV's use of magnetic dipole antennas
(transmission and receiver) give users the ability to survey changes in attenuation rates and phase shifts, enabling mine owners and managers to make better informed decisions on overall mine integrity and ensure continuous coal production without costly shutdown scenarios.