Friends in Radioland -
With signals from the Peter I DXpedtion about to show up on the
band and solar minimum not far off, it is of interest to rate the
challenges that will be presented to DX operators. To that end,
I've developed a rating system, not in terms of distance, but the
loss of a DX station's signal in reaching three centers of amateur
activity - North America (W0), Western Europe (DL) and Asia (JA).
Signal loss is due mainly to ionospheric absorption and signal
spreading. Keeping in mind that absorption loss varies linearly
with distance and spreading varies as the inverse-square of
distance, by defining DX paths as beyond 4,000 km, we can evaluate
paths in ionospheric terms. For the 4,000 km standard path, the
loss on 1.8 mHz due to spreading amounts to 72 dB and about 40 dB
due to absorption at night. Taking those values for 4,000 km
standard paths, we obtain the following for additional losses, in
dB, for DX signals to reach all three centers of amateur activity:
Sub-Antarctic Indian Ocean Western Pacific
VK0H ---- 342 VK9C ---- 245 P2 ----- 216
3Y/P ---- 340 VK9W ---- 242 KC6 ----- 169
VK0 ----- 338 VQ9 ----- 233 DU ----- 160
VP8/SS -- 337 8Q ------ 202 KH2 ----- 156
VP8/SO -- 337 VU/L ---- 183 KH0 ----- 152
VP8/SA -- 335 VU/A ---- 177 KH9 ----- 141
Central Pacific Atlantic Arctic
FO ------ 247 ZD8 ----- 228 OY ------- 59
T31 ----- 209 8P ------ 161 VE8 ------ 57
T33 ----- 198 6Y ------ 142 JX ------- 50
T30 ----- 196 C6 ------ 124 JW ------- 47
KH5 ----- 189 VP9 ----- 107 UA1/FJL -- 46
T32 ----- 188 CU ------- 97 UA1/NZ -- 45
So working Peter I will be comparable to the difficulty earlier in
connection with VK0IR at Heard Island. The "good news" is there
won't be a "dead zone" in western USA, as was the case with VK0IR.
If you're curious about any DX site, just give me the prefix, its
latitude and longitude; I'll send you the rating.
73,
Bob, NM7M
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