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One thing about the mobile 102 whip installations...........people are "tuned" (pun intended) to see 50 ohms and consider that to be the be-all and end-all of a perfect tuning job and stop there. The issue is that since a 1/4 wave antenna is really 35-36 ohms if they were to continue improving their ground the SWR will actually go up slightly which runs contrary to what they think or understand. If they were to continue improving their ground not only would the SWR go up slightly but the efficiency would also go up considerable. This is especially the case with ground mounted verticals using a ground radial field.Without understanding what the impedance SHOULD be it is easy to fool yourself into thinking you have an efficient installation because you see 50 ohms +/- J0 on the analyzer. You can have two installations that both have the same 1.5:1 SWR and yet one will be 6 dB stronger than the other. One case is when you have an impedance of 75 ohms due to high ground losses and an efficiency of only about 50% and the other is when the impedance is near 36 ohms and the efficiency is near 99%. Better yet if the impedance is a perfect 50 ohms the efficiency is really only about 70% despite the apparent "perfect" SWR.

<blockquote data-quote="Captain Kilowatt" data-source="post: 578653" data-attributes="member: 39"><p>One thing about the mobile 102 whip installations...........people are &quot;tuned&quot; (pun intended)&nbsp; to see 50 ohms and consider that to be the be-all and end-all of a perfect tuning job and stop there. The issue is that since a 1/4 wave antenna is really 35-36 ohms if they were to continue improving their ground the SWR will actually go up slightly which runs contrary to what they think or understand. If they were to continue improving their ground not only would the SWR go up slightly but the efficiency would also go up considerable. This is especially the case with ground mounted verticals using a ground radial field.Without understanding what the impedance SHOULD be it is easy to fool yourself into thinking you have an efficient installation because you see 50 ohms +/- J0 on the analyzer. You can have two installations that both have the same 1.5:1 SWR and yet one will be 6 dB stronger than the other. One case is when you have an impedance of 75 ohms due to high ground losses and an efficiency of only about 50% and the other is when the impedance is near 36 ohms and the efficiency is near 99%. Better yet if the impedance is a perfect 50 ohms the efficiency is really only about 70% despite the apparent &quot;perfect&quot; SWR.</p></blockquote><p></p>

[QUOTE="Captain Kilowatt, post: 578653, member: 39"] One thing about the mobile 102 whip installations...........people are "tuned" (pun intended) to see 50 ohms and consider that to be the be-all and end-all of a perfect tuning job and stop there. The issue is that since a 1/4 wave antenna is really 35-36 ohms if they were to continue improving their ground the SWR will actually go up slightly which runs contrary to what they think or understand. If they were to continue improving their ground not only would the SWR go up slightly but the efficiency would also go up considerable. This is especially the case with ground mounted verticals using a ground radial field.Without understanding what the impedance SHOULD be it is easy to fool yourself into thinking you have an efficient installation because you see 50 ohms +/- J0 on the analyzer. You can have two installations that both have the same 1.5:1 SWR and yet one will be 6 dB stronger than the other. One case is when you have an impedance of 75 ohms due to high ground losses and an efficiency of only about 50% and the other is when the impedance is near 36 ohms and the efficiency is near 99%. Better yet if the impedance is a perfect 50 ohms the efficiency is really only about 70% despite the apparent "perfect" SWR. [/QUOTE]

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