Do you remember MEOV?

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Thus MEOV was born. It offered a wonderful means of providing a way around a potential difficulty in meeting the approved radiation pattern. So the wise thing to do whenever a directional antenna pattern was filed was to add a few percent more than the theoretical pattern in any potentially troublesome areas. As time passed it became very unusual to see a proposed DA pattern without an MEOV. As a matter of fact, several consulting engineers have been known to put an MEOV around the full 360 degrees of a pattern. Actually, this is not quite as strange as it sounds. The electronic environment surrounding directional antenna stations is still changing for the worse, and presenting more tower structures than there were 80 years ago. It was becoming more difficult every year to construct and proof a new directional when proposing a new antenna system. In much the same way as MEOV was developed, time passed and another problem involving theoretical patterns and MEOVs began to develop.

Meoving, I mean moving on

Around the end of the 1970s it became apparent that some confusion would often exist for both FCC engineers and consulting engineers; it was often difficult to determine looking through the files whether an MEOV or the theoretical pattern had been used in the final operation. To avoid this increasing confusion the Commission decided to introduce the standard pattern for directional antenna applications. The standard pattern was produced by adding a term representing the minimum allowable radiation to the generally used equation in directional antenna design. Thus was born an acceptable antenna pattern that could never decrease to zero in a null.

The Commission generated and provided a list of standard patterns for all licensed AM directional stations in the early 1980s. Later it issued the edict that all applications involving directional antennas must be based on the standard pattern. It was inevitable, of course, that there would be instances when the standard pattern just couldn't fit due to excessive radiation on one or more azimuths. To take care of these situations, augmentation was allowed as described in the commission's rules. Provided that the excessive radiation did not produce unallowable interference the pattern could be augmented over the pertinent arc. Appropriate information concerning the degree of augmentation used is noted in the directional antenna data. Thus any engineer can easily and accurately obtain precise information on any licensed directional station or applicant and the theoretical DA pattern with MEOV is no longer used.

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