The GWOG Antenna -- A Grounded Wire-On-Ground

Feb 5th, 2021 by Rick Andersen, KE3IJ

One of the first articles written [in 2000] for this hobby-radio website was about using a ground rod as an antenna-- no overhead wire, just a short length of coaxial cable with its inner conductor connected to "ground". And it worked! The idea has always intrigued me, but I went back to using my end-fed wire, and later a full-wave loop antenna [yes, up in the air!] for transmitting in the HF Ham bands and experimenting with such things as my 1-watt version of the Pixie QRP transceiver.

Well, it's 20 years later (!) and I don't get on the air much anymore, but spend my hobby time building simple receivers. Even though I am a Ham, most of these hobby toys, lately, have been built for the AM broadcast band. I suppose I am getting old, and have taken a liking to Zoomer Radio, CFZM, 740 AM, a station in Toronto, Canada that plays oldies during the evening and, during the long cold winter months, comes in pretty strongly here in S. Central PA.  At 12 midnight,"For something completely different", as Monty Python would say, CFZM airs a show called Midnight Blues, hosted by a lady DJ named Ziggy... who plays some of the most hilarious, dirty-lyriced music you've ever heard-- mostly 1930's era Burlesque-type songs. But what's an old fogey like you doing up at that hour, anyhow?

During the summer months, with thunderstorms and the attendant static, radio becomes less fun and growing a vegetable garden becomes my alternate pastime. Mowing the lawn and keeping up with tree and shrub maintenance become the less-fun counterparts to the vegetable garden.

Since 2017 I have been futzing around [my preferred mode of working] with various embodiments of the One-R-Flex which stands for 'One Transistor Regen - Reflex' receiver. For a receive antenna I put together a Ewe which you can see depicted with some of my One-R-Flex schematics. The Ewe antenna worked OK-- I don't have any antenna impedance-measuring equipment to speak of, and I was not transmitting, just receiving, so nothing critical or overwhelmingly wonderful there.

Sometime in 2020, I decided to try the ground antenna idea again, along with the latest permutation of the One-R-Flex, and I am fairly impressed with its performance. Quite respectable by day, and crazy with signals at night, including the aeronautical beacons in the longwave band below 530 KHz [they're slowly shutting them down as obsolete and unneeded, so get 'em while you still can, if listening to repetitive Morse Code IDs is of any interest to you!].

Several years back I came across the Grasswire antenna, by M. Toia, K3MT, which consists of a long insulated wire of about 200 feet, either sitting on or suspended a few inches above the ground.

I decided that I wanted to "tap into whatever is in the ground", so my version of the Grasswire has a ground rod at the far end: the long insulated wire is terminated to ground.

So my GWOG [Grounded Wire-On-Ground] antenna consists of 2 wires and 2 ground rods. [I named it "GWOG" with a tip of the hat to the "LOG" antenna -- which is an acronym for Loop- On-Ground and is being popularized by its inventor, Matt Roberts, KK5JY].

The short wire connects the radio's circuit ground to a ground rod just below the window where the radio sits. That's earth ground #1. The long wire connects to the Antenna terminal on the radio; the wire drops to the ground surface below the window, goes out to the bottom of a fence that divides my property from the neighbor's, and follows that fence (within a foot or so) all the way to the end of the back yard, then turns right, and terminates at a 2nd rod, earth ground #2. The total length is somewhere between 100 and 150 feet. I have not buried the wire, just let it sit on the ground surface. I bought a roll of #18 or larger [can't remember the gauge] stranded wire with red plastic insulation. Somewhere in the backyard, I spliced another piece to the end of the red wire; this one was green [the electrons don't care] and finally connected the far end to the clamp on earth ground rod #2. During the summer I was careful not to run the wire over with the lawnmower. As I write this in February of 2021, there is a foot of snow on the ground, and the GWOG antenna works just as well as it did without the snow, at least to my uncalibrated ear.

Note, in the illustration below, that the two wires that enter the window sill are connected to their own, isolated series L-C circuit, consisting of a ferrite rod from an old transistor radio, wound with 50-60 turns of #22 magnet wire, and a 365 pF metal plate tuning capacitor. The only connection to the radio is to its copper ground plane [chassis]; the tuning cap is grounded to the chassis. That tuning cap is named the Antenna/GND Peaking cap, and its job is to tune the 'antenna' and 'ground' connections to series resonance at the radio station's frequency. Since a series resonant circuit provides a minimum impedance, Z, between the two points connected to its ends, there will be maximum RF current flowing through the coil L at resonance. Inside the latest embodiment of the One-R-Flex receiver, the ferrite rod just described stands vertically [anchored by candle wax dripped around its base], approximately 2.5" away from a 2nd ferrite rod with 55 turns of wire on it... this 2nd coil forms the L-C tuning circuit with another 365 pF variable capacitor; this 2nd cap is the Main Tuning cap in the radio. [The 2.5 inch spacing between the two ferrite rods was found by experimentation: Any farther apart, and overall signal strength would drop off; any closer, and there would be overload and overlap; i.e, selectivity would be impacted.]

So there is only magnetic coupling between the radio and the outside world. I did this because simple radio front-ends often lack the ability to reject unwanted stations that come blasting through (so two LC filters are better than one!), and I wanted to milk every last drop of signal I could get from this crazy "ground" antenna, by maximizing the series-resonant antenna current through the first inductor. Overall, I refer to this as both Antenna Peaking, and Ground Tuning. Several of the old-fashioned [and new-fashioned] Crystal Radio designs use a similar technique to improve both sensitivty and selectivity.

See illustration:

So what are some advantages of an on-ground antenna?

1) I don't have to go to the trouble of stringing it up high in the air

2) It's invisible to the neighbors, unless you point it out to them

3) It's virtually lightning-proof!

4) Along the same lines, it's pretty noise-free, compared to some up-in-the-air antennas

5) Wind and snow storms won't bring it down!

6) Maintenance is simple

I also wanted to give a plug to my source for these beautiful metal plate tuning capacitors:
They are newly-manufactured units available from Borden Radio Company, http://www.xtalman.com

The 365 pF tuning caps are available, last I checked, for under $20 each. The website has several different types and sizes of variable caps, as well as other categories of parts for those interested in building crystal sets.

FYI, if you are unfamiliar with this: The 365 pF metal-mesh caps I am describing here are the type and the value of caps used from the tube radios of the 1920s until the 1960s, when they began to be replaced by the small "polyvaricon" plastic-case capacitors that you will see in the cheap portable AM-FM radios built since the 1960s. The plastic capacitors usually range from 140 to 170 pF in value, with the plates fully-meshed (= 'bottom' of the tuning dial). They require an inductance L of 600 uH or thereabouts, to resonate in the 530-1700 KHz AM broadcast band.

The older, metal-plate caps that Borden Radio Company makes and which I recommend, are 365 pF when fully-meshed, and that requires less inductance in your coil; 240 uH is the usual value. I find that about 50-60 turns of #22 or #24 magnet wire, wound on a 3-4" ferrite rod from an old transistor radio, gives me that ballpark's worth of inductance, so as to tune the AM band with a metal-plate 365 pF tuning cap.

The resonant frequency for any L-C pair can be calculated by the formula:

f = 1 / (2pi x sqrt(L x C))

where:

2pi= 6.28

L= Inductance in Henries; 1 microhenry = 1 uH = 1 x 10^-6 Henries

C= Capacitance in Farads; 1 picoFarad = 1 pF = 1 x 10^-12 Farads

sqrt stands for "square root of"


f= Frequency in Hertz [=Hz =cycles per second = cps in the old notation]

1 KHz = 1000 Hz; 1 MHz = 1,000,000 Hz

Frequency = the rate at which a radio wave "flaps" from (+) to (-) in polarity

[In music, Pitch = the frequency at which a sound wave is vibrating]

When you 'wiggle' air fast enough, you produce a sound wave;

When you 'wiggle' an electric charge fast enough along a metal conductor

known as an antenna, you produce an electromagnetic- or radio wave

When a radio wave is vibrating REALLY fast, like 10^14 Hz, you perceive it as Light



TRANSMITTING into the GWOG: My first contact, Feb. 2021

I have been listening to AM BCB and Longwave using my "GWOG" antenna. I am also playing around with a Pixie on 80m [receiving] with colorburst XTAL... somewhat surprised that 80m is coming in so nicely on the grounded wire. [I have NO antennas in the air right now.]

On a goofy whim, I decided to try my luck transmitting into the grounded wire, laying along the ground, out 100-150 feet and terminated at a ground rod. Under 6 inches of snow.

The trusty old Kenwood TS-520s tuned up [without any external antenna tuner] with a sharp dip in plate current, and I heard SSB activity on 14 MHz. which was a surprise in itself, given I was listening with a long. grounded wire, on the ground! Just as a guy was ending his QSO with someone else, I called him and he answered me! I gave him an S7 and he gave me an S4 to S7 [fading]. I told him I was doing a crazy experiment, transmitting into a long wire, on the ground, under the snow, and grounded at the far end! He remarked that it sounded to him like my antenna was a well-intentioned "dummy load"; my thinking was that he was several states away from me; this dummy load shouldn't even be working that far!

Our QSO took place at 5:30 in the afternoon on Feb. 14th, 2021, on 14.269 MHz. His call was W5WZ, located in Calhoun, Louisiana. I forgot how much power he was using, but he mentioned using Tri-Bander antennas. My output power with the Kenwood was in the neighborhood of 100 watts. I kept thinking that there was some kind of twisted analogy between my running 100W into a grounded "dummy load", and the loyal group of QRPers who try to get a signal out with their Pixie kits putting out 100 milliWatts! It's nuts, but it can be done! And here I thought a long, grounded wire might only work for AM and Longwave!



Here is the original article on using a ground point as an antenna with a simple AM radio:

An AM radio that uses the Earth as the Antenna

I read an article on the Keelynet website that piqued my interest a couple of years ago: It was all about receiving and transmitting radio signals through the ground. The story goes that underground antennas were experimented with as far back as Tesla, and a 1912 patent by one James Harris Rodgers shows several ways of implementing an antenna which amounts to burying a dipole or helix in the ground, and, I assume, depending on the ground currents (induced by the radio wave being transmitted above the ground) to provide long distance, relatively static-free radio reception. This involved both transmitting and receiving; I decided to K.I.S.S. [keep it simple, stupid!] and play around with just the receiving part.

The schematic shows a simple TRF-like AM detector feeding a Radio Shack amplified speaker (the little beige ones they've sold for many years at $13.95), whose "front end" is connected, not to a suspended antenna, but to a grounded rod, through a short piece of coaxial cable.

Please notice the 240 uH inductor on the input antenna lead: If you can find an old transistor radio with a cylindrical ferrite rod antenna, slip the rod in and out of the antenna coil until you peak the station you're listening to -- you're basically adding electrical length to the short, high-impedance ground antenna which probably looks predominantly capacitive (the XL cancels the XC and the circuit resonates better with the outside world).

Using two transistors in a Darlington configuration raises the impedance seen by the LC tuned circuit, giving less loading and more selectivity.

The 1 k ohm resistor in the base of the Darlington transistor pair helps prevent oscillation; the 330 pF to ground on the transistors was found to improve the overall gain (volume).

Like any or all of these simple radios, you're not to expect superb performance; rather, the fascination is in how well they do work for such a small parts count. The "ground" radio did do better with a normal, above-ground antenna, but it did a surprisingly good job picking up AM radio stations "through the ground" also.

A variation on this setup would be to pound another ground rod some feet away, and connect the circuit's ground to that one. You would most likely need to readjust the inductance at the front end to accomodate the new impedance.

You do hear some static and impulse noise, by the way, during a Summer night when thunderstorms are approaching. But in general this radio is quieter, static-wise, than a radio using "sky waves".


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