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When you did your EFHW vertical, the coil had a tap on it, was that the same type of tapped coil used in this 5/8, or was the tap simply to vary the inductance? (I'm thinking the latter but am not 100% sure)

As I have recently been informed in another thread adjusting the tap point doesn't change the resonant frequency on a tapped coil antenna such as this one. What I see happening on a 5/8 is instead of tuning the length to resonance, you can set the length to the optimum radiating length for whichever frequency you wish to use, then use the capacitor to fine tune the resonance, and you can still use the tap point to tune impedance.

I would say that this design appears to be an attempt to be able to keep that perfect .64 wavelength and be able to adjust both resonance and impedance independently of adjusting the antenna length.

I would think this design would be less efficient than just a straight tapped coil and adjusting antenna length for resonance, but the radiation pattern would be changed slightly as well. Personally for a 5/8 I would go with efficiency side as the difference even going from .625 (5/8) wavelength to .64 wavelength is small enough of a difference that anyone receiving the signal would not notice.

That being said, as you pointed out, if someone wanted a high power handling version of an antenna such as your EFHW I could definitely see a use for it there or any other design that would require a capacitor.

The DB

<blockquote data-quote="The DB" data-source="post: 397852" data-attributes="member: 21346">When you did your EFHW vertical, the coil had a tap on it, was that the same type of tapped coil used in this 5/8, or was the tap simply to vary the inductance?&nbsp; (I&#039;m thinking the latter but am not 100% sure)As I have recently been informed in another thread adjusting the tap point doesn&#039;t change the resonant frequency on a tapped coil antenna such as this one.&nbsp; What I see happening on a 5/8 is instead of tuning the length to resonance, you can set the length to the optimum radiating length for whichever frequency you wish to use, then use the capacitor to fine tune the resonance, and you can still use the tap point to tune impedance.I would say that this design appears to be an attempt to be able to keep that perfect .64 wavelength and be able to adjust both resonance and impedance independently of adjusting the antenna length.I would think this design would be less efficient than just a straight tapped coil and adjusting antenna length for resonance, but the radiation pattern would be changed slightly as well.&nbsp; Personally for a 5/8 I would go with efficiency side as the difference even going from .625 (5/8) wavelength to .64 wavelength is small enough of a difference that anyone receiving the signal would not notice.That being said, as you pointed out, if someone wanted a high power handling version of an antenna such as your EFHW I could definitely see a use for it there or any other design that would require a capacitor.The DB</blockquote>

[QUOTE="The DB, post: 397852, member: 21346"] When you did your EFHW vertical, the coil had a tap on it, was that the same type of tapped coil used in this 5/8, or was the tap simply to vary the inductance? (I'm thinking the latter but am not 100% sure) As I have recently been informed in another thread adjusting the tap point doesn't change the resonant frequency on a tapped coil antenna such as this one. What I see happening on a 5/8 is instead of tuning the length to resonance, you can set the length to the optimum radiating length for whichever frequency you wish to use, then use the capacitor to fine tune the resonance, and you can still use the tap point to tune impedance. I would say that this design appears to be an attempt to be able to keep that perfect .64 wavelength and be able to adjust both resonance and impedance independently of adjusting the antenna length. I would think this design would be less efficient than just a straight tapped coil and adjusting antenna length for resonance, but the radiation pattern would be changed slightly as well. Personally for a 5/8 I would go with efficiency side as the difference even going from .625 (5/8) wavelength to .64 wavelength is small enough of a difference that anyone receiving the signal would not notice. That being said, as you pointed out, if someone wanted a high power handling version of an antenna such as your EFHW I could definitely see a use for it there or any other design that would require a capacitor. The DB [/QUOTE]

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