You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
The Feb 2025 Radioddity Giveaway Results are In! Click Here to see who won!

Reply to thread

Message

DB,

Everything looks fine to me. Looking at what you have though, the whip is 102" + 6" +2" = 110" = 9.1666667'. 234/9.1666667 = 25.5273 MHz or so. Stray capacitance from the cable has shifted the resonance point to 29.66655 MHz. You will notice that resonance is where the phase = 0 (where the purple line crosses the 0 line). There are 15 points of resonance shown on your graph. But your system is primarily resonant at 29.66655 MHz as eveident by the Return Loss curve. Your RL = 26.44 dB for a value that's near to 1.1:1 VSWR. (Note: As a reference, a VSWR of 1.01:1 = a Return Loss (RL) of 45.8 dB). The fact that the antenna never exceeds 100 ohms is most likely due to the cable losses of your RG-8X cable, or the lack of bonding, or both. You would have to measure the antenna with a short 6" cable to get a better answer. I don't know where you want the antenna to work best at? But it works great at 29.66655 MHz the way it is.

Mike

<blockquote data-quote="KC9Q" data-source="post: 406399" data-attributes="member: 23691">DB,&nbsp;Everything looks fine to me.&nbsp; Looking at what you have though, the whip is 102&quot; + 6&quot; +2&quot; = 110&quot; = 9.1666667&#039;.&nbsp; 234/9.1666667 = 25.5273 MHz or so.&nbsp; Stray capacitance from the cable has shifted the resonance point to 29.66655 MHz.&nbsp; You will notice that resonance is where the phase = 0 (where the purple line crosses the 0 line).&nbsp; There are 15 points of resonance shown on your graph.&nbsp; But your system is primarily resonant at 29.66655 MHz as eveident by the Return Loss curve.&nbsp; Your RL = 26.44 dB for a value that&#039;s near to 1.1:1 VSWR.&nbsp; (Note: As a reference, a VSWR of 1.01:1 = a Return Loss (RL) of 45.8 dB).&nbsp; The fact that the antenna never exceeds 100 ohms is most likely due to the cable losses of your RG-8X cable, or the lack of bonding, or both.&nbsp; You would have to measure the antenna with a short 6&quot; cable to get a better answer.&nbsp; I don&#039;t know where you want the antenna to work best at? But it works great at 29.66655 MHz the way it is.&nbsp;Mike</blockquote>

[QUOTE="KC9Q, post: 406399, member: 23691"] DB, Everything looks fine to me. Looking at what you have though, the whip is 102" + 6" +2" = 110" = 9.1666667'. 234/9.1666667 = 25.5273 MHz or so. Stray capacitance from the cable has shifted the resonance point to 29.66655 MHz. You will notice that resonance is where the phase = 0 (where the purple line crosses the 0 line). There are 15 points of resonance shown on your graph. But your system is primarily resonant at 29.66655 MHz as eveident by the Return Loss curve. Your RL = 26.44 dB for a value that's near to 1.1:1 VSWR. (Note: As a reference, a VSWR of 1.01:1 = a Return Loss (RL) of 45.8 dB). The fact that the antenna never exceeds 100 ohms is most likely due to the cable losses of your RG-8X cable, or the lack of bonding, or both. You would have to measure the antenna with a short 6" cable to get a better answer. I don't know where you want the antenna to work best at? But it works great at 29.66655 MHz the way it is. Mike [/QUOTE]

Top Bottom