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