Reference
The complete register
Twenty-two entries in seven sections. Each one is a single propagation or hardware fact and the operating consequence of it.
01 · Propagation
Ground wave, skywave and the layers.| No. | Entry | The fact, and its consequence |
|---|---|---|
| 01.1 | Ground wave | The signal that follows the curve of the earth, and why soil conductivity decides how far it gets. |
| 01.2 | Skywave | Refraction off the ionosphere, and why it turns a local transmitter into a long-distance one after dark. |
| 01.3 | The D layer | The absorbing layer that exists only in daylight — the single fact behind almost every peculiarity of AM broadcasting. |
| 01.4 | Appleton's proof | Edward Appleton measured the reflecting layer experimentally and took the 1947 Nobel Prize for it. |
02 · Day and Night
Why the same transmitter is two different stations.| No. | Entry | The fact, and its consequence |
|---|---|---|
| 02.1 | Licensed two ways | Separate day and night power, and why a transmitter drops power or changes pattern at sunset. |
| 02.2 | Clear channels | Frequencies protected for long-distance night coverage, and WLW Cincinnati running 500 kW in the 1930s before it was stopped. |
| 02.3 | Sunrise and sunset | The switch follows the sun, not the clock, which is why the schedule moves through the year. |
03 · The Mast
The antenna is the structure.| No. | Entry | The fact, and its consequence |
|---|---|---|
| 03.1 | The mast is the antenna | A series-fed tower radiates as a whole and stands on an insulator, which is why its height is chosen in wavelengths rather than metres. |
| 03.2 | Ground radials | Buried copper doing half the work; a poor ground system wastes power no transmitter can make back. |
| 03.3 | The Blaw-Knox tower | The diamond cantilever, widest at its middle and balanced on a single base insulator. |
04 · The Array
Steering a signal by phase.| No. | Entry | The fact, and its consequence |
|---|---|---|
| 04.1 | Phase and pattern | Two or more towers fed with a controlled phase difference produce a pattern that protects one direction and reinforces another. |
| 04.2 | Nulls | The deliberately quiet direction, and how deep a null can actually be held in practice. |
| 04.3 | Phasors and tuning | The cabinet that sets the ratio, and why an array has to be re-proofed after work. |
05 · Modulation
AM, FM and what each does under interference.| No. | Entry | The fact, and its consequence |
|---|---|---|
| 05.1 | Amplitude modulation | Encoding in the envelope, which is simple to detect and defenceless against noise that arrives the same way. |
| 05.2 | Frequency modulation | Edwin Armstrong's alternative, the capture effect, and why FM sounds clean and then vanishes rather than degrading. |
| 05.3 | Digital carriage | What actually changed when transmission went digital, and what did not. |
06 · Fading
Multipath, selective fading and the fixes.| No. | Entry | The fact, and its consequence |
|---|---|---|
| 06.1 | Selective fading | Two paths arriving out of phase at some frequencies and not others, which is why the distortion sounds like it is inside the voice. |
| 06.2 | Multipath | Reflections off terrain and buildings, and what they do to FM in a moving car. |
| 06.3 | The Grimeton exception | SAQ in Sweden, an Alexanderson alternator from 1924, still transmitting on 17.2 kHz at a wavelength that barely fades at all. |
07 · Measurement
Field strength, and how coverage is actually known.| No. | Entry | The fact, and its consequence |
|---|---|---|
| 07.1 | Field strength | Coverage is measured, not calculated — a meter, a route and a map of readings. |
| 07.2 | Proof of performance | The measured demonstration that an array is doing what its licence says. |
| 07.3 | What a contour means | A coverage contour is a statistical statement about a field strength, not a fence. |