The Truth about the G5RV Antenna

And Two Other Improved Alternatives To This Basic Design

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G5RV antenna

And Two Other Improved Alternatives To This Basic Design

The G5RV Antenna


Although the popular G5RV antenna is often promoted as an antenna that works well on all bands from 80 through 10 meters, that is absolutely NOT the case.

This is not to say that the G5RV doesn’t work well on SOME bands. But it does NOT work well on ALL HF bands. That’s my point.

There are some bands where the SWR on the coax is out of sight and the feedline losses are astronomical.

The Classic G5RV Antenna

The ZS6BKW Antenna


Depending on which bands you want to operate, there is a better design which involves shortening the antenna and lengthening the section of ladder line. G0GSF (ex-ZS6BKW) came up with a similar design that is a significant improvement over the G5RV.  Even that design still doesn’t cover all the HF bands

The ZS6BKW’s top section is 93′ (instead of 102′),
 and the 400 ohm ladder line matching section is 39.8′, (instead of 30.6′).

Before you buy or build that G5RV, do yourself a favor and Google g5rv ZS6BKW|G0GSF.


To summarize:

  • Neither the G5RV nor the ZS6BKW antenna works on 30 or 60 meters.
  • The G5RV does NOT work well on 17 or 10 meters. The SWR is a little better on 80 than the ZS6BKW.
  • The ZS6BKW does NOT work well on 15 meters, and needs a tuner to work well on 80.

The W0BTU Antenna


Our modification to the G5RV and ZS6BKW antennas, while also somewhat of a compromise of frequency ranges and VSWR, lets us use all HF bands between 80 and 10 except 30 and 60* meters.

EZNEC file for the W0BTU version, which uses a 97′ straight top section, a 39.5′ (or 31′; see below) length of “450 ohm” (usually, the actual Z is 420 ohms) window line, and 75 ohm coax feedline.

You can tweak the lengths slightly to suit your height, operating preferences, etc. The design height of these SWR plots is 40′ above ground.

  • Plot 1: Frequency vs. SWR plot with 39.5′ balanced line, 75 ohms (3.5-29.7 MHz)
  • Plot 2: Frequency vs. SWR plot with 31.0′ balanced line, 75 ohms (3.5-29.7 MHz)
  • Plot 3: Frequency vs. SWR plot with 31.0′ balanced line, 50 ohms (3.5-29.7 MHz)
  • 10 Meters: Intentionally optimized for the upper portion of 10 meters

The above bands can be used without switching the feedline, just like the ZS6BKW antenna. However, removing 8.5′ so that the length of the open wire line is 31′ lets this new design also work well on 75/80 and 15 meters.


The W0BTU antenna covers more bands than either the G5RV or the ZS6BKW

A simple DPDT knife switch (or banana plugs and jacks) near ground level lets us use 75/80 and 15 meters, if desired. Even though the VSWR is relatively high on 75 and 80 meters, lower coax loss on that band at least lets us operate there using just one multiband antenna.

NOTE: The remaining 8.5′ section is not connected in any way on 75, 80, or 15 meters. It must be totally removed from the feedline. If one end of it is left connected, the antenna doesn’t work right.

* Well, it will work on 60 meters, if you use a 76′ length of the 420 ohm window line; SWR is below 1.5:1.


Note that the SWR values in the above charts are at the antenna. Some commercial G5RV antenna designs rely on the loss in a long coax feedline to bring their claimed SWR down in lieu of—or in addition to—an antenna tuner.

Balun

You should use a ferrite-core broadband 1:1 current balun (choke) right at the junction of the window line and coax to keep RF off the outside of the coax shield. We used one of K9YC’s (Jim Brown) designs using about 6 turns of the 75 ohm coax feedline wound through 4 or 5 stacked Fair-Rite 2.4″ diameter #31 ferrite cores. A “ugly” balun made from coax wound on an air core is not recommended, as it does not span near as wide a frequency range (see G3TXQ Chokes).


A much better alternative to any of these three antenna designs is running the open-wire line from the center of a dipole all the way to a balanced antenna tuner, which was recommended by Louis Varney, G5RV himself. That antenna will work on ANY band from 80 through 10 meters. (And that’s what I eventually did with this improved antenna design here at my QTH.)



References:


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I'd rather build and experiment than talk on the radio. Most of my QSOs have been to check the performance of my latest antenna, rig, etc. I have a soldering iron in my hand FAR more often than a key or microphone. Weak signal work such as 160 Meters, VHF DXing

3 COMMENTS

  1. I have a dipole antenna about 40′ above ground in the center and 20 feet on each end. Each leg is approximately 134 ft. long. It is fed with ladder-line all the way from my Ten Tec tuner to the dipole. Is the 100′ length of ladder-line. I also have a built in turner in my Yaesu FT 450D.
    Is the ladder line the reason I am able to tune up on the 160M band?
    Thanks for the information you’ve shared.

  2. I’ve sent you a msg in QRZ regarding Louis Varney’s antenna. Some diagrams and letter from him to his friend explaining the antenna and what not. The letter is in Spanish but the drawings are legible so u can see all the numbers and measurements. I hope you get something out if and if not at least you can say you’ve seen Louis Varney’s letter about the antenna, 73 W9QK.

  3. Very sorry but antenna doesn’t depend on SWR, SWR means nothing, it just say the system isn’t 50 Ohm.
    You are very wrong, the G5RV works on any band if you meet 2 conditions.

    1: Use high quality coax like H100 and not RG58 or RG213.
    2: Use a good tuner that will tune it 50 Ohm for the tranceiver.

    As for the ZS6BKW, it does not work on 80m, it’s a dummyload as the radiators are too short to function on 80m.

    Impedance is not the same as resonance. Also, coax losses at high SWR are minimal with good coax.

    You should know that the G5RV is a dipole, but it will never be 50 Ohm on all bands, this isn’t important either.
    SWR is a non issue, it tells you nothing and an analyzer is just a s stupid.

    Impedance and resonance matter a lot, a dummyload is perfect impedance but does not resonate at all.

    You can not beat a G5RV if you know what you are doing, it will work. The ZS6BKW does not below 60m.
    I worked the entire world on 10m with the G5RV, even worked a lot of stations on 6m 🙂

    Get a decend tuner like an Palstar AT2K and your G5RV will work everywhere, no problems at all except 160m.

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