Update on Radio Mapping Baylor Peak

I'm hoping to do a few more ham radio POTA activations of New Mexico parks today. In prep, here's a bit more data on the Organ Mountains-Desert Peaks activation.

In documenting the 'add your own QSO' feature on the RBN tracker, I created a few interesting pictures I thought I'd add as an update to my earlier ocmments on radio optics and mountains. The following picture shows the spots, (blue lines), and QSOs, (green lines), made during a few days worth of activations. From the perpective of the entire countyr, a rough pattern becomes apparent:

Zooming into the peak, we can see why:

(Basically, the neighboring mountain is affecting propagation.)

Of particular interest to me though: notice the pattern of the QSOs when the radio was located further up Baylor Peak. There are fewer QSOs headed out to the North. I think (but don't have enough data to support) this might have been caused by the antenna's angle of radiation being reduced due to the steeper slopes on either side of it from that location..

I had gone up the mountain hoping to get a better line of sight around the peak, but I think I may have also lowered the angle of radiation (check out the nice long QSO to Florida, although the QSO to near DC was from furhter down the slope; I need more data) with those two slopes to such an extent that the radio was transmitting straight into the peak to the north.

For simplicity, first consider an antenna on the top of a hill with a constant slope downward. The general effect is to lower the effective elevation angle by an amount equal to the downslope of the hill. For example, if the downslope is −3° for a long distance away from the tower and the flat-ground peak elevation angle is 10° (due to the height of the antenna), then the net result will be 10° − 3° = 7° peak angle.

--from the very fb "Antenna Height and Communications Effectiveness" by By R. Dean Straw, N6BV, and Gerald L. Hall, K1TD.

References:

POTA is Parks on the Air, an organization of ham radio operators who operate from parks all over the world. It's a fun way to get outdoors with a radio.

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