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I am having difficulty understanding the Azimuth and Elevation charts on page 81 of the CWNA 3rd ed book.

The text at the bottom of the page describes how the antennas intersect at certain points on the maps. It says "The coverage contour intersects at the 90 degree radial at the -15dB point" I have stared at the maps and I do not see this intersection or the others described in this section.

Could someone please help me understand how to correctly read these maps.

If you look closely at the top diagram (E-plane), you'll see dB values running across the horizontal line from the middle toward the 90 degree mark.

At -15dB, the RF coverage line (the oblong pattern) crosses the 90 degree line. So, when the antenna is pointed 0 degrees relative to your position, RF coverage will drop off significantly after it reaches -15db for a device to the right of that antenna.

In comparison, on Antenna #2, RF coverage is almost non-existant for devices to the right of that antenna since the RF coverage line shows almost no coverage at 90 degrees for the E-plane.

Joel

I see my problem. I was looking at the numbers and I attributed them to the wrong lines so I could never see what was in the book. Thanks for the explanation.

Glad to help.

Joel