Six Band Propagation Test with Two Antennas and 10W vs 100W

Thought of conducting propagation test on six HF bands for which I have provision. For 40, 20, 15 and 10m bands I use a three band fan dipole antenna, with 15m working on third harmonic of 40m elements. That antenna is an inverted V with apex at about 10m from the ground. Second antenna is a zig-zag linear loaded inverted V dipole meant for 80m, but working only on 30m and 12m currently. Apex of that antenna in inverted V fashion is at 7m from the ground. All tests were based on pickup at Reverse Beacon Network. To prevent RBN skimmers from ignoring sequential calls, calls with 10W power were made 5kHz up compared to the calls on 100W. This chart shows propagation on RBN with 100W. Pick up was noted only on four bands. There were no pickups on 20m and 12m. Yet I could hear VU3FGJ working ARSI contest on 20m with a booming 5,9+ 20 dB signal. Of course there are no RBN skimmers near his region.

Of more interest to me was the propagation with 10W. RBN skimmer at VU2PTT picked up my signal on 30m with a signal to noise ratio of 6dB, while 100W signal had been picked up with SNR of 11 dB. So 5 dB difference at 171 miles for a 10 times difference in power. VR2FUN-77 had picked up my 10W signal with SNR of 6 dB on 10m, compared to 13 dB with 100W. That was a difference of 7 dB for 10 times power difference at a distance of 2568 miles. Obviously 10m had fared better for DX propagation. But the antennas were different. 10m was with multi-band inverted V dipole with apex at 10m from the ground. 30m was with zig-zag linear loaded inverted V dipole meant for 80m, a very sub optimal antenna with apex at just 7m from the ground. I had expected propagation on 12m as well for that antenna, but had no luck this time.