Last weekend I had the chance to play with my HamWAN portable setup (this is the Poynting dish, RouterBoard Metal 5SHPn, 11.1V battery, and tripod combo you see on http://hamwan.org/ homepage). I set up at the Camano Island survey location shown on the map. It's right at water level with a clear view toward Everett. When I first set up, I got a signal level of about -58 dBm. Wow! This is great for 21 miles at 5.9 GHz. As the tide went out, I saw the signal dip to around -76 dBm. This was over about 250 yards of mudflats. As the tide came back in, I saw the signal climb until the water reached the bulkhead (about 5 ft from antenna), and the signal level hit -54 dBm. The computer model predicts a path loss of 145 dB, which would put my signal level at -71 dBm. You can see from the numbers that the water improves the signal level. This was not predicted. What causes it? Kenny linked me to an interesting paper on the topic, although my observations differed from theirs: http://www.researchgate.net/publication/224138836_Slow_Frequency_Hopping_for... I find the effect of tides on signal level very intriguing. This is the sort of effect that makes 5.9 GHz microwave interesting to me. Tom KD7LXL