Commentary

Experiment 3. This was a measurement of a section of line I constructed years ago. Measurements were made only up to 100 megahertz where the fixture was useful. It really only shows the ability to make measurements of high impedance line that seem credible, using time domain and gating to remove unwanted reflections. As for most of the experiments, observe the improvement in ripple when unwanted terms are ignored.

Experiment 4. This experiment is also limited to 100 megahertz maximum with similar gating and results. However, this time one conductor is terminated on both ports by using wet saw previously measured asa load. This demonstrated an increased attenuation of about six DB corresponding to half the voltage being delivered to the port two. In addition, there’s another two and a half dB or so of attenuation. Even so, it demonstrates that a single wire can transmit energy across significant distances.

Experiment 5. This is the first measurement using a tapered transmission line transformer. I use the standalone measurement ability of the NanoVNA Without the benefit of time domain processing. Only a side view of the tapered transformer in the foreground is visible. Periodic terms due to re reflection and aliasing can be seen in the yellow reflection plot. Like most of the experiments, this was performed a few feet above a wooden fence with metal rabbit wire screening. This distance was determined to be adequate to not add significant effect to any of the measurements.

Experiment 6. This is the first measurement which builds on the previous involving deliberate bends in the transmission line. Because I already had the wide space two line set up, I was able to simply deflect it with styrofoam wheels. The first of these non-bend situations quantifies the degree of impact a wheel touching the line has. When that was seen to be negligible, larger and larger bends, three places were included. Note the low radiation from the center of line, the region of the bends, at the same time there is increasing attenuation and transmission. This implies that the energy was being lost to radiation.

Experiment 7. Here with essentially the same setup as experiment six, a one meter extra length of line was applied to one conductor. If the two conductors are independent, as hypothesized, then this should include an extra 180 degrees, a phase reversal, at port two. The P44 trace shows the inclusion of that length and the large dip in attenuation where it is 180 degrees near 150 MHz. Then note that these seemingly in-phase signals on the two conductors were combined to a single wire connection, as in the previous experiments. It can be seen that uh almost the total attenuation observed in a previous experiment was observed here. There is no extra loss.

Experiment 9. Here I resurrected two old single wire launchers, that is, test fixtures, and remeasured them. They’ve been in storage for years, and I wanted to see if the results were the same as before. They seem to be, but do note for later reference the ripple below the design cutoff frequency for these launchers, which was somewhere a little bit below 150 megahertz. There are characteristic periodic peaks that are show ripple in frequency domain but low attenuation at some points. This is an indication that it is possible to make a efficient surface wave launcher with dimensions a good deal shorter than those indicated by the Klopfenstein tapered equation.

Experiment 10. This experiment is somewhat the reverse of the previous one, where a single wire line is split into two balance lines with a one-meter extra length again inserted to provide differential drive to port two. Prior to this insertion, it can be seen that there is also and again a large dip near150 megahertz when port two receives two in phase components Shown here in Maroon. . The loss due to one of the fixtures has not been calibrated out.

Experiment 11. This is a demonstration of use of common cat-side conductor to create a higher impedance line. It’s being fixtured with a lump transformer rather than tapered as in the previous experiments but continues to show very low attenuation across the 80-foot length. Again, one meter of extra conductor is inserted demonstrating the phase reversal and nulling at port two when that is one half wavelength.

Experiment 12. This experiment is a potpourri providing tools and advice for general use of additional or further experiments. It includes two methods for determining a line’s characteristic impedance. One is the classic method of measuring the reactive portion when the line is an eighth wavelength long. The other is a TRL calibration tool created for the purpose. This experiment also serves to introduce the Jupiter notebook as a convenient environment for analysis.

Experiment 14 This experiment Uses the original QEX single wire launchers to to make an estimate of the use of a 2-way split and also to compare different single wire conductor diameters. The data shows approximately a three DB decrease in transmission due to half of the power being terminated.

Experiment 15 This experiment again qualifies the use of styrofoam as a deflector for intentionally adding bends in a wire conductor. The foam sheet is simply common household insulation with a notch cut into it, which encloses the wire. The data shows no significant difference between its presence and absence.

Experiment 16 In this experiment, the entire length of the line is bent at right angles at the center By the previous styrofoam sheet.. The Radius of the bend is controlled by slots in the styrofoam.. The data shows relatively small additional reflection due to the presence of the bend. And slightly more attenuation as could be expected for the additional total line length. The data shows a small frequency dependent increase in attenuation as the radius of bend is reduced.

Experiment 17 This experiment qualifies and calibrates the Field Probe for use of radiation measurement near 150 megahertz. Accurate antenna factor calibration for this probe has not been done otherwise yet, so this was considered useful. Because the calibration at the field probe was the same one used for the line and through condition, there is an additional error, a mismatch, uh at the probe’s 50 ohm terminus. Because the fixture calibrated is absent, signal levels will tend to be about four tenths of a DB higher than they really should be.

Experiment 18. This is the first radiation measurement. For it, the probe was kept at the calibration distance from the center of the line, perhaps a little bit too close. It was then moved along the length of the line starting at Port One and proceeding most of the way to Port Two, where n f f f f f f f f f f f f f f f f f f f foliage prevented f further measurement. The large peak near Port One occurred in the vicinity of the end of the Klopfenstein tapered launcher, where mode conversion between TEM and TM is occurring. This is by far the largest radiation anywhere on the line. Radiation near the center may be attributed to direct leakage from the VNA which was located at the center right below the measurement point. A reconfiguration of the equipment removed the VNA and allowed measurement at various distances away from the center. The data seems to reflect a measurement floor which may be attributable to radiation from the launchers at each end. The the geometry of the test situation is not great enough to allow a lower limit.

Experiment 19. Many years ago on larger SWTL I performed these obstruction measurements but did not document them. The results are useful for understanding and should be repeated (by someone).