G5RV Dipole Antenna Height vs Tuning with a RigExpert AA-55 ZOOM/BT

[Peter Wolczko]

After reading about the Antenna Analyzers, I will be picking up my RigExpert AA-55 ZOOM/BT at HRO on Monday ( thanks to the upcoming present from the Feds). My question is: When I tune my new G5RV at about 6-10 feet up, using the analyzer, how will that correlate to the Dipole’s final height of about 40 feet?

Thank you all for the information.

Thank you.

Peter  KC1FNF

[Hamilton]

Hello Peter,

The antenna is in parallel with the ground. At the low height the ground will reduce the impedance. Think of the ground as a resistor in parallel. Also the propagation velocity will be somewhat slower which will make the antenna appear electrically longer for a given physical length.

Both of these effects are sensitive to wave length.

At 10m you are starting at  around 1/3 wavelength above ground and then raising it to over 1 wavelength at 40′. As you get past 1/2 wavelength  the ground will have less effect.

At 40m the height above ground  remains less than 1/2 wave and therefore Z and length will remain sensitive to height all the way up to 40 feet.

Congratulations on a nice analyzer, I also have the 55 Zoom. I wish I had BT.  With BT I would hoist the antenna with the meter attached to get the Z at the feed without any transmission line effects.

[Nashua Area Radio Society]

The following link may provide some helpful insight into the G5RV antenna operation:   https://www.hamuniverse.com/g5rv.html

The parallel transmission line used is an integral part of the matching process of the radiating antenna wire and coax system used to connect it to your radio.  The goal of the parallel transmission line is to transform the actual impedance at the radiating antenna wire down to something that can be matched by an antenna tuner.  A tuner is needed on all bands except 20 meters (but will help there also).

This line should not be coiled up or left laying on the ground when measurements are being made  with your analyzer.  The analyzer will provide good insight of how the antenna will respond on each of the other bands, but the best measurement point will be with the antenna fully erected and then measured at the point where it actually enters your radio.

Hope this helps.

Mike – k1wvo

 

[Peter Wolczko]

I appreciate all of the information that was sent to me. I now  will  do some reading and if I have any  more questions I certainly will reach out. Today, while it was very windy,  I was outside looking at which trees I would be using for the G5RV dipole. I picked the trees that swayed the least for setting up the dipole next month.

Many thanks to Hamilton- K1HMS , and Mike K1WVO

 

73,

Peter  KC1FNF

[Author]

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