```Dear LF Group, ```Dick's experiments looking at V and I on a 'scope simply demonstrate that the antenna was resonant - voltage and current in phase being one way of defining resonance in an LC circuit. This does not mean that significant currents are not flowing in the distributed capacitance of the coil or that they are in or out of phase with the applied voltage, just that the overall resultant voltage and current at the feed point are in phase. At my station, I use what is effectively the same method as Dick's experiment to tune my antenna during normal use - see the article in the LF handbook. It has the advantage that you can see at a glance if the antenna is resonant, and if the load resistance is correct. Any 2 conductors anywhere will have some capacitance between them. The distributed capacitance between a loading coil and ground can be quite substantial - several 10s of pF - because the coil has a big diameter compared to the antenna wire, and is close to the ground. A current must flow in the distributed capacitance, because there is a voltage between the coil and surroundings. The loading coil terminals and ground effectively form a 3 terminal impedance matching network containing distributed elements. For a small antenna with the resulting big loading coil, the current at each end of the coil will be significantly different due to the current flowing in the distributed capacitance. Conversely, a big antenna requiring a small loading coil with distributed capacitance much smaller than the antenna capacitance will have little difference in current at it's ends The distributed capacitance won't significantly reduce the overall efficiency of an antenna, provided the loss in the distributed capacitance is small compared to the overall antenna losses. It just means that a greater current is required at the cold end of the coil to get a particular antenna current. To minimise additional losses, much the same considerations should apply to siting the coil as the rest of the antenna, ie. as far as possible from lossy dielectric materials. Since the ground is a very lossy dielectric, there is a lot to be said for raising the coil off the ground as far as possible. The altenative is a low - loss electrostatic screen, to prevent the electric field of the high voltage parts of the coil reaching the lossy dielectrics. G3YXM seems to have done this succesfully, completely surrounding the coil. I once tried a similar experiment to GW4ALG's, covering a 3m x 3m area of ground around the loading coil with wire mesh, but it made no observable difference to the loss resistance. But then, my coil is already about 1.5m off the ground. There was only a few percent difference in current between the hot and cold ends of the coil, but my antenna is considerably bigger than Steve's, with about 50m of wire in total (305pF capacitance). When I had an indoor loading coil (with a similar antenna), the difference in current was considerably higher, about 10%, presumably due to higher distributed capacity Since most amateur LF antennas are high impedance devices (ie, high voltages, relatively low currents), I would guess that the dielectric losses will normally dominate the magnetic ones (hysteresis, eddy currents). The magnetic field of a coil falls off rapidly with distance - an inverse cube law, I believe, so keeping it a reasonable distance away from conducting materials is probably adequate to minimise the magnetic losses. However, a poorly designed electrostatic shield around a loading coil might increase the eddy current losses drasticaly. Any kind of experiment that involves measurement of V or I at the "hot" end of the coil using an oscilloscope is going to be very difficult to obtain meaningful results from - any connecting leads will considerably alter the capacitances, and the high electric and magnetic fields will induce signals in leads and probes that lead to erroneous results. Phase measurements using a 'scope are notoriously inaccurate, and small changes in phase will be hard to detect reliably. ```Cheers, Jim Moritz 73 de M0BMU ```