We propose that the meridian system as a whole is one grand transmission line, excited periodically at a frequency of f50, the frequency of the 50-round circulation (0.578 x 10(-3) Hz). This grand transmission line is analyzed as a 28-leg, uniform, low pass (LP) electromagnetic (EM) birdcage coil, consisting of capacitors and inductors. The second lowest resonant frequency (mode 1) of the birdcage is f50. Each leg represents one channel and is analyzed as a lossless transmission line itself. The amplitude of the Qi standing wave on each channel is periodically amplified at f50. The average number of acupoints on the 28 channels involved in the 50-round circulation and the speed of Qi were used to calculate the resonant frequencies. A mechanical birdcage consisting of mass and spring may co-exist and exchange energy with the EM birdcage. Magnetic resonance imaging (MRI) may be used to map the diffusion coefficient, elastic modulus and electric conductivity of tissues in vivo, as an indirect evidence of the existence of the proposed EM and mechanical standing waves.