29 September, 2011

Communication with vector potential waves

Field lines (black) and potential (red) for a dipole, static field. 
In QEX July/August 2011 Robert K. Zimmerman (NP4B, VE3RKZ) had an intriguing article entitled "Transmission and Reception of Longitudinally-Polarized Momentum Waves."  What he claims is that he has communicated over a distance of 1500 m at 1296 MHz using vector potential or momentum waves.

Unlike transversal electromagnetic (TEM) waves these are longitudinal waves just like sound waves. This may seem like real magic, but if true it would allow covert communications which is undetectable with ordinary radio receivers and antennas.

The electric scalar potential around a dipole is shown in red in the figure. This is for static dipole charges where the potential is usually denoted φ. The time-varying case is more complex and has an additional magnetic vector potential A which has three components, in total a 4-component vector potential.

If I understand the papers right, it is one of the components of the A-vector that is used in these experiments, and it seems to be one component of the curl-free vector potential (thus without a magnetic field) alluded to initially here. But as I could not find any figure showing that, I chose to show the nearest I could find, the electric scalar potential φ. (Figure from the Equipotential page of Hyperphysics.)

Zimmerman has made an experiment with a transmitter antenna inside a 7" round waveguide of length 69 cm. I think the intention is that the TEM wave cannot escape from this waveguide, only the vector potential wave. On the receiver side he has used a similar waveguide with a folded fluorescent tube, the type which is used in camping lanterns. The fluorescent tube is arranged geometrically in such a way as to be insensitive to TEM waves.

I am open to new ideas and find the whole concept very interesting. On the other hand I wish that he had documented the whole experiment better, by for instance demonstrating how he had listened with an ordinary receiver and antenna to convince himself and us, his readers, that there really wasn't any TEM wave emitted. Also I wish that he would have provided more detailed explanations of how the transmitter and receiver antennas work in the QEX-article and in his other paper "Macroscopic Aharanov-Bohm Effect at L-band microwave frequencies," Modern Physics Letters B. 2011.

Now the Aharonov-Bohm effect is a real particle physics phenomenon which has both been predicted in theory (1959) and also shown in experiment (1986). It is nicely illustrated on the Physics World pages. It shows that the vector potential is indeed real and influences particles. But here the claim is that it manifests itself not only in the microscopic domain, but also at the macroscopic level. Although I am more positive than the "Software Safety" blog, I remain for now interested, but so far unconvinced, and awaiting more evidence.