JohnnyMac Sends: A True Multi-Band Antenna

Originally appearing on his forum, Unchained Preppers, this post is a pretty good summary of improvements needed to make a very common antenna, the G5RV, an actual multi-band solution. While I don’t use the G5RV, I recognize a lot of folks do, so this might be pretty important if you’re looking to boost its capability.

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I have been shopping for a new G5RV type antenna since Radio Works in VA. was sold. I currently have one running east-west (North south lopes) and I wanted one that goes north-south (west-east lopes). The new owner is focusing his production in a different direction than the G5RV right now. What it comes down to, is for me to make my own G5RV antenna.

Knowing that some of you are working on new antenna’s over the winter I thought I would share this with the folks here.

Now many folks carry manufactured G5RV antenna’s and market them as multi-band antenna’s when in fact they are not. They are weak on 75/80 and 10-meters and will not pick up 60, 30, and 15 meters. Eventually my search lead me to reading an article entitled, The Truth about the G5RV Antenna.

The article spoke to two different versions of the G5RV antenna – The ZS6BKW and W0BTU Antenna’s. As it is tough in life to get an all encompassing piece of equipment ala “getting your cake and eating it too”, both the ZS6BKW and W0BTU antenna’s are an improvement over the G5RV antenna however, neither one is all encompassing.

Because I hate wasting my time, and prefer doing something once rather than twice, I contacted Cecil Moore, W5DXP who has reportedly made some considerable improvements to the ZS6BKW and W0BTU antenna’s.

Moore and I have been trading emails over the past few months and he just published an article entitled How to Transform Your ZS6BKW Into an All-HF-Band Antenna.

In essence the antenna is a dipole flattop 92′ long with 39′ of 450 ohm ladder line into a 1:1 choke-balun to 50 ohm coax. If you just did this your SWR’s (Standing Wave Ratio) would be the following in the following band’s:

Meter      SWR
80           4.5*
60           >10**
40           1.4
30           >10**
20           1.3
17           1.4
15           >10**
12           1.2
10           1.6

If you don’t want to have to use a tuner you really want to keep SWR below 1.5. If you use a tuner to control SWR lets say taming a high SWR, there is no tuner I am aware of that will bring an antenna’s SWR down south of 2.0 if the SWR is north of 10.0.

*   You will need a tuner
** You can not tune

These results bring us to Option 1.

Option 1:

To bring 80-meters down to 1.2 SWR add a 500pf Doorknob capacitor*** post the 1:1 balun on the center coax center conductor. When you do this the SWR on 80-meters drops to around 1.2. The capacitor does not adversely affect SWR when left in line to 40, 20, 17, 12, & 10-meters.

*** Leaving the capacitor in line does not adversely affect the higher frequencies when you add ladder line as described in Option 2.

Option 2:

What can you do to optimize 40, 20, 17, 12, & 10-meters after adding the capacitor for 80-meters is to add/delete 450 ohm ladder line in 1 or 2-foot lengths. An easy way to do this without manually adding/deleting ladder line using banana clips, is to use a DPDT knife switch. By adding one or two feet to the existing 39-feet of ladder line helps SWR in the 40, 20, 17, 12, & 10-meter bands with the capacitor still in line.

Here are the SWR’s for the following frequency’s with an inline capacitor and by adding 1-2-feet of ladder line to the original 39-feet of ladder line via the DPDT knife switch.

Meters  SWR           Configuration
80         1.2                500pf capacitor & original 39′ Ladder line
60         >10**
40         1.5                500pf capacitor using knife switch add 1′ ladder line
30         >10**
20         1.0                500pf capacitor using knife switch add 1′ ladder line
17         1.4                500pf capacitor original 39′ ladder line no additions
15         >10**
12         1.2                500pf capacitor using knife switch add 1′ ladder line
10         1.8                500pf capacitor using knife switch add 2′ ladder line

Option 3:

By using options 1 & 2 combined, SWR is great except for 60, 30, and 15-meters. Now we get into a bit more complicated procedure as it involves a couple more knife switches, a relay switch, and some additional capacitors (60-meters a 128pf, 30-meters 104pf, 15-meters  44.5pf). If you execute on this last procedure you will in fact have a true multi-band antenna from 80-10-meters.

This is what the SWR looks like for 60, 30, & 15-meters.

Meters  SWR             Configuration
80           1.2                Capacitor & original 39′ Ladder line
   60       1.5               Using knife switch add 2′ ladder line PLUS using relay switch add 128pf capacitor
40           1.5                 Using knife switch add 1′ ladder line
   30       1.1               Using knife switch add 2′ ladder line PLUS using relay switch add 104pf capacitor
20           1.0                Using knife switch add 1′ ladder line
17           1.4                Original 39′ ladder line no additions
  15        1.0               Original 39′ ladder line PLUS using relay switch add 44.5pf capacitor
12           1.2                Using knife switch add 1′ ladder line
10           1.8                Using knife switch add 2′ ladder line

Please take the time to read both articles as they do much more justice than my short explanation does complete with PICTURES and GRAPHS.

With deer season ending for now, and my outside projects coming to a close do to weather, I will build this antenna and document all of my moves. Once done I will hoist and let you know how it works.

73!

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Want to know how it all works? How about building your own antennas? I run a class for that. Check the training calendar and consider coming out for a class.

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10 thoughts on “JohnnyMac Sends: A True Multi-Band Antenna

  1. mistermisfit01

    I apologise in advance. I had to read a few times to wrap my brain around this design. What I eventually come away with is a lot of failure points. And from a risk management perspective, in times of peace this has merits, in times like we have now, keeping things simple may be a better avenue. Imo fwiw

    Liked by 1 person

    1. Apologize? Nah 😉 The G5RV is what it is. A lot of folks use them for their relative simplicity once put up. The problem is that the doublet antenna was designed for use on 20m and works best at a specific height. Making it work on other bands is a major pain that can be solved by simply building your own dipole cut for the band you want.

      But with THAT said, the antenna is in use with a lot of folks, especially newer or less experienced people, as well as people who have limited space or other environmental constraints. So it’s good for them to know how to modify what they might have.

      I don’t use the G5RV, I’ve built all my own antennas, HF-UHF. And I teach others to do the same 😀

      Liked by 1 person

  2. mistermisfit01

    Don’t get me wrong. I have my tarheel 400A on my vehicle. I had a 43′ vertical at my old QTH. I also have a chameleon hybrid I have experimented with portable at QRP. But I do love my dipole. Efficient and without need of a tuner. Can be made into a directional V. Quick up and down. Small footprint in the air and in a pouch. I’ve been low key practicing what you have been preaching. I still love my slick gear, but that stuff is not practical in the coming balkanization. Keep up the field craft stuff. I’m listening and practicing.

    Liked by 2 people

  3. Donald Woodruff

    Or you can simply buy a My Antenna. This remarkable antenna works well on 80 down.
    Single wire (132′) with matching circuitry based on principles espoused by Tesla.
    I have used one on field days and could work any band with no tuner. The antenna was
    suspended 20 feet in the air.
    W9DLW

    Liked by 2 people

  4. funny I know that its not a perfect antenna the g5rv but It still works. Anything is better than nothing. And when you want to put just one antenna up its easy to do. I bought one and put it up. Made contacts all over the world on all frequencies. Even 160 meters. so while you can say its not a good antenna and doesn’t perform well I would say well that may be true but ive made contacts on it so I can’t complain.

    Liked by 2 people

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