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1/2 wave end fed with 1/4 wave radials vs. 5/8 wave

Here are two 1/2 wave models with 1/4 wave radials that are isolated and not. There also are two 5/8 models with 1/4 wave radials to compare how the 1/2 wave is not so affected using isolation or radials. Both 1/2 waves show high current flow and there is little difference between isolated and not isolated.

I found similar results in my limited real life testing of an A99 with/without radials even though I was not able to measure the current distribution per se. I noticed minimal effects from adding radials to this end fed 1/2 wave antenna. The only question I still have about such testing is Bob suggesting that the way I isolated my mast could have been an issue. I isolated using PVC around the mounting portion of the antenna mast, instead of raising the antenna above the mast 4"-6".

This said however, you will note in comparing the 5/8 to the 1/2 wave patterns, that all lobes for the 1/2 wave are virtually the same whether isolated or not, while the 5/8 wave highest lobe for the isolated antenna is notably lower than the antenna that is not isolated.

[ATTACH]6190[/ATTACH]

Again the feed lines are not included in the models and where isolation and radials seem to mitigate the problems with high current flow, attaching the feed line can provide the necessary current path to ground.

<blockquote data-quote="Marconi" data-source="post: 338149" data-attributes="member: 903">1/2 wave end fed with 1/4 wave radials vs. 5/8 waveHere are two 1/2 wave models with 1/4 wave radials that are isolated and not. There also are two 5/8 models with 1/4 wave radials to compare how the 1/2 wave is not so affected using isolation or radials. Both 1/2 waves show high current flow and there is little difference between isolated and not isolated.&nbsp;I found similar results in my limited real life testing of an A99 with/without radials even though I was not able to measure the current distribution per se. I noticed minimal effects from adding radials to this end fed 1/2 wave antenna. The only question I still have about such testing is Bob suggesting that the way I isolated my mast could have been an issue. I isolated using PVC around the mounting portion of the antenna mast, instead of raising the antenna above the mast 4&quot;-6&quot;.&nbsp;This said however, you will note in comparing the 5/8 to the 1/2 wave patterns, that all lobes for the 1/2 wave are virtually the same whether isolated or not, while the 5/8 wave highest lobe for the isolated antenna is notably lower than the antenna that is not isolated.&nbsp;[ATTACH]6190[/ATTACH]&nbsp;Again the feed lines are not included in the models and where isolation and radials seem to mitigate the problems with high current flow, attaching the feed line can provide the necessary current path to ground.</blockquote>

[QUOTE="Marconi, post: 338149, member: 903"] [b]1/2 wave end fed with 1/4 wave radials vs. 5/8 wave[/b] Here are two 1/2 wave models with 1/4 wave radials that are isolated and not. There also are two 5/8 models with 1/4 wave radials to compare how the 1/2 wave is not so affected using isolation or radials. Both 1/2 waves show high current flow and there is little difference between isolated and not isolated. I found similar results in my limited real life testing of an A99 with/without radials even though I was not able to measure the current distribution per se. I noticed minimal effects from adding radials to this end fed 1/2 wave antenna. The only question I still have about such testing is Bob suggesting that the way I isolated my mast could have been an issue. I isolated using PVC around the mounting portion of the antenna mast, instead of raising the antenna above the mast 4"-6". This said however, you will note in comparing the 5/8 to the 1/2 wave patterns, that all lobes for the 1/2 wave are virtually the same whether isolated or not, while the 5/8 wave highest lobe for the isolated antenna is notably lower than the antenna that is not isolated. [ATTACH]6190.vB[/ATTACH] Again the feed lines are not included in the models and where isolation and radials seem to mitigate the problems with high current flow, attaching the feed line can provide the necessary current path to ground. [/QUOTE]

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