Mijo, In a distant way, there is a relationship between a transmission line and a dipole design, or whatever you call the type where two woofers are working in or out of phase, back to front or front to front. The transmission line is akin to an open baffle where the rear radiation is used to augment the very low frequency bass output by undergoing a phase change in the course of passing through the transmission line and out through the port at the base. But the cabinet does not damp the motion of the woofer, as in open baffle.
Raul, I was a lowly intern when I first heard the IMF Monitor at Lyric Hi-Fi in NYC. I wanted that speaker very badly but could not afford what seemed to be the stupendous price at the time, $1000 I think. I had a patient who offered me the use of his bench saw, so I bought the HDF, clamps, glue, drill, etc, and built the transmission line exactly according to the IMF Monitor, which was based on a published paper in a British journal called "Wireless World". A guy named Bailey described the TL in one issue of the journal and gave all information needed to make the cabinet using a KEF B139 woofer. Then my home-made version used a KEF B100 midrange, as in the Monitor, and RTR Electrostatic tweeters, 4 per side, that I bought from a guy in CA who was associated with Infinity, which was then making the Servo-Statik 1. The problem then was that I knew nothing about crossover design. I got some help with that from an MIT-trained engineer who worked for NSA here in the DC area. I eventually sold the speakers to my cousin, and then bought them back from him about 20 years later. I cut off the midrange and tweeters and saved the TL woofer cabinet, which I now use along with the Beveridge 2SW, as the outboard woofers.