ANTENTOP- 01- 2018 # 022

The Inverted L Ham Antenna

The Inverted L Ham Antenna

By Robert M. See, W5LTD

Credit Line: Radio and TV- news, January 1959, pp.: 64- 65.

Construction of simple antenna and matching network that provides a good compromise in height, cost, and coverage.

After moving into a new home it was hoped that a satisfactory solution could be found to the problem of installing an amateur antenna without detracting from an appearance of the neighborhood landscaping. This, of course, ruled out any type feedline which would hang suspended and flapping in the Oklahoma breeze. Naturally the buried coax feedline and all- band vertical came to mind. After considerable thought (this is always the hard part), it was decided to modify the vertical radiator to include some horizontal polarization. It was believed that this might increase the field strength, on 80 and 40 meters, over that of a vertical- at least within a 300-mile radius. In other words, we didn't want our signal to skip our local friends. As a consequence, the Inverted L Antenna- which is a compromise in height, cost, and coverage- was adopted.

The utility pole was set 5 feet into the ground and has withstood 70 mph wind gust without guy wires. It is located on the rear of a city lot, nestled in a group of eastern red cedar trees. It takes a sharp eye to detect any discontinuity in the landscape.

Radio and TV- news, January 1959

The XYL believes this to be the best part of the entire installation, however, the author is partial to its operation and the strong signal reports received.

Figure 1 shows the horizontal radiation patterns on three bands for which the antenna was designed. It would be possible to operate the antenna on 15 and 10 meters with the proper matching networks but these bands have not been investigated.

Antenna Construction

The vertical portion of the antenna is made from a 32.5-foot section of ½-inch I.D. copper water tubing. It is mounted on 4-inch ceramic stand-off insulators which are, in turn, fastened to the telephone pole. The copper tubing can be purchased in coils of varying length and was used because it was easy to handle and workable. The horizontal portion of the antenna is 32.5 feet of # 12 AWG (2-mm) stranded copper antenna wire.

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