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The radiation patterns of the 5/8 wave deserve a closer look because they do support the idea that inverting the antenna can reduce skywave activity. Notice what is happening to the gain in the 15 to 20 degree range. When the antenna is inverted we see a null there. Right side up and we have a secondary lobe peaking out right in that range. Your specific results will obviously vary with height.

Marconi, with respect to the wide angle Vector, there is a point of diminishing return with this idea that was not pointed out in the old Avanti patent. They mention that wider angles can increase gain but avoid the fact the physical length of the cone section must line up with the first electrical 1/4 wavelength of the main radiator. This is important to confine the undesired radiation taking place inside the cone. Since the electrical length of the cone and loop combined must also equal 1/4 wavelength, there is only one ideal dimension that meets all of the requirements.

As mentioned earlier, my consideration of inverting my antenna was for specific installations where two antennas must be stacked and phased together. At .82 wavelength long, this makes the standard vertical stacking distance difficult to achieve without negative interaction. The very high RF voltage tip of the bottom antenna is too close to the grounded side mount bracket for the antenna above it. That creates a prime location for a Corona arc to take place.

If I invert the bottom antenna, that problem goes away. It may also create a situation where the nulls in one antennas pattern can be more easily filled in by the second antenna. It does appear that none of this will provide downward beam tilt over real earth however, with the stacked pair this option is easily added with a small phase delay inserted with one antenna.

<blockquote data-quote="Shockwave" data-source="post: 384984" data-attributes="member: 10882">The radiation patterns of the 5/8 wave deserve a closer look because they do support the idea that inverting the antenna can reduce skywave activity. Notice what is happening to the gain in the 15 to 20 degree range. When the antenna is inverted we see a null there. Right side up and we have a secondary lobe peaking out right in that range. Your specific results will obviously vary with height.Marconi, with respect to the wide angle Vector, there is a point of diminishing return with this idea that was not pointed out in the old Avanti patent. They mention that wider angles can increase gain but avoid the fact the physical length of the cone section must line up with the first electrical 1/4 wavelength of the main radiator. This is important to confine the undesired radiation taking place inside the cone. Since the electrical length of the cone and loop combined must also equal 1/4 wavelength, there is only one ideal dimension that meets all of the requirements.As&nbsp; mentioned earlier, my consideration of inverting my antenna was for specific installations where two antennas must be stacked and phased together. At .82 wavelength long, this makes the standard vertical stacking distance difficult to achieve without negative interaction. The very high RF voltage tip of the bottom antenna is too close to the grounded side mount bracket for the antenna above it. That creates a prime location for a Corona arc to take place.If I invert the bottom antenna, that problem goes away. It may also create a situation where the nulls in one antennas pattern can be more easily filled in by the second antenna. It does appear that none of this will provide downward beam tilt over real earth however, with the stacked pair this option is easily added with a small phase delay inserted with one antenna.</blockquote>

[QUOTE="Shockwave, post: 384984, member: 10882"] The radiation patterns of the 5/8 wave deserve a closer look because they do support the idea that inverting the antenna can reduce skywave activity. Notice what is happening to the gain in the 15 to 20 degree range. When the antenna is inverted we see a null there. Right side up and we have a secondary lobe peaking out right in that range. Your specific results will obviously vary with height. Marconi, with respect to the wide angle Vector, there is a point of diminishing return with this idea that was not pointed out in the old Avanti patent. They mention that wider angles can increase gain but avoid the fact the physical length of the cone section must line up with the first electrical 1/4 wavelength of the main radiator. This is important to confine the undesired radiation taking place inside the cone. Since the electrical length of the cone and loop combined must also equal 1/4 wavelength, there is only one ideal dimension that meets all of the requirements. As mentioned earlier, my consideration of inverting my antenna was for specific installations where two antennas must be stacked and phased together. At .82 wavelength long, this makes the standard vertical stacking distance difficult to achieve without negative interaction. The very high RF voltage tip of the bottom antenna is too close to the grounded side mount bracket for the antenna above it. That creates a prime location for a Corona arc to take place. If I invert the bottom antenna, that problem goes away. It may also create a situation where the nulls in one antennas pattern can be more easily filled in by the second antenna. It does appear that none of this will provide downward beam tilt over real earth however, with the stacked pair this option is easily added with a small phase delay inserted with one antenna. [/QUOTE]

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