W6CAW Antenna Test Range

Metal vs. Fiberglass Support Masts

So, the next question is, how does the mast type effect the antenna? Here I took one of my putty knife 80 Meter OCF's and ran RigExpert scans with it mounted on the Test Range metal mast and my fiberglass pushup mast.

Test setup. The masts are about 20 feet apart. Wonder if that effects the measurement?

Click on images below for a larger graph.

The bold line is the antenna on the fiberglass mast. The light line is the antenna on the metal mast.
The bold 40M dip is at 7.105 MHz with a |Z| of 22.4 ohms.
The biggest dip around 20M is 15.552 MHz with a |Z| of 55.3 ohms.
I assume the shift in and the double dips on 40M on the metal mast has something to do with the metal mast being
roughly 1/4 wave at 40 Meters? More detail below.

More detail at 80M, the primary frequency of the antenna.

So, does the conductivity of the mast effect a OCF dipole. Probably. Can you over come any errors by tuning the antenna length. It appears so.

Another shot of the setup. The RigExpert and laptop are on the table under the umbrella.

I try not to suffer in retirement!

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