I note that a reasonable

*a priori*case can be made on the basis of propagation characteristics that somewhat different metrics in the G(Δ, n) series might be better representations of RBN coverage on some of the bands. However, rather than make this into a full-scale research project, I shall simply use the G(15, 100) metric on the basis that it seems "good enough" on all bands.

#### RBN Posting Stations as a Function of Time

We begin by looking simply at how the number of per-band posters to the RBN has varied since the RBN's inception. (NB Throughout this post, we ignore posters for which the location is not recorded by the RBN; plots for which the abscissa is time show one datum per month.)

First, a plot of the total number of posters as a function of time:

Now similar plots for the HF bands (in this post I exclude 60m, but include the low bands even though 160m is not technically HF).

10m:

12m:

15m:

17m:

20m:

30m:

40m:

80m:

160m:

These can usefully be represented on a single summary plot that preserves the interesting features of the above graphs:

#### G(15, 100) as a Function of Time

Turning now to the mensal values of G(15, 100), we obtain the following plots. First, the value covering posters from all bands:

And for the individual bands, starting with 10m:

12m:

15m:

17m:

20m:

30m:

40m:

80m:

160m:

As before, a summary plot is useful (if only for making it depressingly obvious how much room remains for improvement in coverage):

#### G(15, 100) as a Function of the Number of Posters

Finally, we can combine the mensal values of G(15, 100) and the number of posters. Firstly, including all bands:

And for individual bands, starting with 10m:

12m:

15m:

17m:

20m:

30m:

40m:

80m:

160m:

The summary plot for these data is slightly different, as the ordinate is multi-valued for some values of the abscissa. So, in this summary plot, we take the mean value of G(15, 100) in bins of width equivalent to ten posters, and plot rectangles in the equivalent colours:

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