[Lowfer] LF/MF Groundwave Comparison

[John Andrews]

What follows is not exceptionally scientific, but may be of interest.

I ran some daytime low power WOLF tests on 508.5 kHz earlier in the 
week. Looking back through my notes, I did some similar tests on 136.3 
kHz, again during the day, at this time of year in 2005. Over this 130 
mile path, the results were very similar. 50 milliwatts consistently 
produced copy on the same line number in both cases. The same transmit 
and receive loop antennas were used on both bands, with appropriate 
tuning networks.

This indicates that with my xmit/receive setups, the groundwave signal 
to noise ratio must be similar at the two frequencies. Note that there 
is an estimated 27 dB higher groundwave path loss at 508.5 vs 136.3 kHz. 
The results probably point to better antenna performance and lower noise 
at 508.5 kHz.

Just one other observation: I could get reliable mid-day copy over this 
path using WOLF and 20 milliwatts output power. Not bad!

John Andrews, W1TAG