Saturating Ground Systems Underneath Limited Space Verticals

Saturating Ground Systems Underneath Limited Space Verticals

By

James Thomas, VA3JT

Bill DesJardins, W1ZY

Introduction

Many hams in the suburbs do not have enough space to install full-sized radial systems underneath their verticals, especially on the lower bands. These limitations are exasperated by commercial manufacturers who tell customers to cut sets of quarter-wavelength (wl) radials for each band covered by their verticals.

Return currents sought by these ground systems are concentrated in the area immediately surrounding the base of the vertical. As we move away from this area, these return currents fall off precipitously. Therefore, when full-size (1/4 wl) radials cannot be installed in all directions, the next best thing is to saturate the ground immediately surrounding the base of the vertical with as many short radials as possible. The example of a full-size 40 meter vertical surrounded by 120 1/4wl radials illustrates this point.

Although the ground radial system defining this “ideal” vertical installation eliminates all ground losses, it collects most of the return current near the vertical’s base. We can think of this area as the “filet mignon” of return current distribution since this area is richest with these currents. 

Accompanying this fact is the coincidence that the 120 ground radials are found converging towards one another within this “filet mignon” area. 

That’s pretty cool because it means that the area where the return currents are most dense is also the area where the ground radial distribution is most dense. Naturally, as we move away from this area, the 120 radials diverge away from one another, rendering the ground radial field increasingly coarse. Thus, as we get closer to the vertical, the return currents and ground screen get denser, yet the further we move away from the vertical, the weaker are the ground currents distributed over an increasingly sparse radial field. 

What all of this boils down too is that each radial collects most of its return current along the first 1/3 to ½ of its length. 

On 40 Meters, for example, this means that the first ten to fifteen feet of each ground radial delivers the most bang for your buck because it captures maximum return current per unit length. The second half of the ground radial does not fare nearly as well.

What makes 120 radials so “ideal” is its packing of the “filet

Mignon” area with so many radials. The fact that each radial

extends out one quarter wavelength is of lesser importance.

When viewed in this light, it is theoretically possible to install a vertical with 120 radials in your suburban backyard. The only proviso being that not all of the radials will end up being 1/4 wl long.

What this means is that if you lay down a lot of short radials

around the base of your vertical, in this case 120 of them in the “filet mignon” area, the ground radial density it establishes equals that of 120 “full-size” radials. It’s the exact same radial field; it just doesn’t extend out as far. Ground radial densities established by large numbers of full-sized radials can be replicated in limited spaces by using an equal number of shorter radials laid out in conformity with the whatever space is available. This is a mind-blowing revelation for many hams who do not lay down any radials when they encounter the condition that they cannot be 1/4 wavelength long. It is the key to getting a backyard vertical to work well. Even if the shorter radials are only two or three feet long.

***

In 2016, I left New York to care-take elderly parents in my

hometown in southern Rhode Island. This afforded me an

opportunity to horse around with a pair of 40 meter elevated

phased verticals in a wooded grove behind their house. I did this for a couple years, tweaking the array to the point where old timers told me to “keep (my) hands off it” because I had

tweaked it to perfection.  I ended up with 30 elevated radials per vertical, a 30 to 35 dB front-to-back ratio and a take-off angle modeled around 19°. It was a lot of fun, and I learned a lot. The project maintained my sanity.  I blogged about it on my “bio” page on QRZ.com to provide other hams with details, charts and photographs. Towards the end of my tenure, I got into the practice of heading out to the garage after dinner, where the station was set-up, and flipping the array to the West in order to work American stations, many of whom had questions about all they had been reading on the QRZ.com blog.

One rainy night a Canadian station with a puny signal checked in.  Between static crashes I understood he was using a multiband vertical in his backyard and that he wanted advice on how to improve its performance. 

I told him to saturate the ground immediately surrounding the base of his vertical with as many radials as possible regardless of how short they were. 

I remember telling him that even if they end up being only 2 feet long, put them in anyway. He thanked me for my advice and faded into the noise.

After dinner a few weeks later, a Canadian station checked in

with a pretty good signal. The operator said his name was James and asked if I remembered our previous QSO. I didn’t.

Excitedly, he recalled for me the advice I had given him, quickly adding he was now working DX over distances never before encountered with his vertical. I remembered him and our first QSO and the advice I had given. I could tell from his excited transmissions that he had become addicted to adding radials to his vertical’s ground system. He had figured it all out, he told me. In three days his XYL was going out shopping. After she left, he and a buddy were planning to lift up all the patio stones in the backyard in order to lay-out more short radials. And then get all the stones back in place before the wife got home. This was a real ham.

James, VA3JT, had truly grasped the importance of saturating the area around the base of his vertical with as many radials as he could. And as I predicted in our first QSO, after doubling the number of radials in his ground system his “perfect 1:1 SWR match” was no longer there. By adding more radials, he had reduced the input impedance of his vertical, causing it to approach the coveted 36 Ohms — the vertical’s theoretical radiation resistance. This produced a SWR approaching 1.3 to 1.  James happily reported his worsening SWR situation, and that his vertical’s impedance was approaching the mid-40’s. 

He was excited because he made the connection between laying down short radials and increasing DX signal reports.

A week later James reappears with a commanding signal. Those DX reports were off the charts — Europe, Pacific, and Antarctica.  I smiled as the list went on. The XYL never suspected that the patio stones had been lifted, James whispered. 

During each of these QSO’S I asked James to document everything he was doing up there in Canada, for his work would benefit thousands of hams wanting to improve the efficiency of their backyard verticals.

CONTINUE WITH JAMES’S FIELD EXPERIENCE HERE

Hello Folks.  This is James.  VA3JT.  

One of the secrets to success is too listen to the advice of others and emulate their success.

After listening to Bill W1ZY on forty meters testing his phased verticals.  I decided to call him when he finished his QSO.  I gave him a five nine plus thirty report.  I wont tell you the report that Bill gave me.  However Bill gave me some amazing advice.  I could not wait until the next morning to get started.

Although I don’t have the real estate space Bill has.  The project was worth the try.  Nothing ventured, nothing gained.

Lets go back in time.  For 35 years I lived in a Penthouse 22^nd floor Apt.  It was near the edge of the Niagara Escarpment over looking Great Lake Ontario.  The 360* view was spectacular.  Water as far as you could see.

My rig in those days was a Drake Line with a linear amplifier.  The antenna was a three-element beam on the roof.  I was in Ham Heaven.  When winter came I would lock the door and go to 6Y5 land.

As the years went passed by.  I was alone and getting older. I started to get lonely.  One night I said to God:  I am getting old and lonely.  My life has been dangerous.  Perhaps its time too get married.

God said:  Go ahead.  I said: don’t push.  You pick the person for me.  I don’t want to make a mistake.  

A few days later I was in a Chinese restaurant with a buddy.  We were having lunch.  This beautiful blonde lady walks through the door.  She was take-out for sure. 

God spoke to me.  He said:  “This is the wife I choose for you.  Take care of her.”  Two weeks later we were married.  It was December 11, 2004.  We have traveled the world together.

HOWEVER, BE CAREFUL WHAT YOU ASK FOR.

I was up on the roof of the building one evening at sunset working on the antenna.  I knew in my heart it would be my last sunset from that QTH.

The apartment was too small for two people.  I gave my station to a fellow ham operator who put it in storage.  We moved from the big city to a small town.  Our new QTH was in the middle of a town house complex surrounded by lots of homes.

 I DEVELOPED A LIMITED SPACE COMPLEX.  Our backyard was 20ft x 20ft.  I was devastated.  For twelve years I was off the air.

There was nothing I could do.  I tried Echo-link.  Not for me.  I tried two meters.  No DX.  Not for me.  

Upon returning home from winter vacation I looked out the back window.  My neighbor had built an18 ft high walk out patio off their second floor and fenced in their back yard.  

WHOW.  Next day I fenced in our back yard.

IT WAS TIME TO GET BACK ON THE AIR.

I decided to keep the antenna as LOW PROFILE as possible.  I borrowed a rig from a friend and put up a half-sized G5RV in the form of an inverted V.  The apex hung from the bedroom window.

The neighbors were asking me why I had all that wire hanging from my window.  

I took it down and bought a hustler vertical.  No complaints.

I bought the vertical because I was told it didn’t need radials.

The only place I could put the antenna was in the corner of the yard close to the fence.  I put a three-foot pipe into the ground.  No radials.  I had very weak signal reports.  I added four ¼ wave zigzag radials for the forty-meter band.  There was just a slight improvement.   I am from the old school that told us that radials had to be a ¼ wave long.   

After listening to Bill W1ZY I was converted.  What I was taught was the immaculate misconception.  I found out radials don’t have to be ¼ wave long.

Vertical antenna manufactures tell us you don’t need radials for their products.

Listen closely to what I learned from W1ZY.  

With a vertical antenna you are only half way there.  The other half of the antenna is the ground.  How do I maximize the gain of my vertical antenna?  You need good ground conductivity for the vertical antenna to function properly.   Our housing complex was built on a potato farm.   The ground is solid clay and gravel.  There is no ground conductivity.  Verticals rely on return ground currents as part of the antenna system.

If you don’t have a good ground system under your antenna its no better than a dummy load.

Ground radials don’t have to be resonant.  I realized the more short radials at the base of the vertical the better of you are.  I went through the junk box looking for any and all sizes of wire of any length I could find.

Following W1ZY ‘s advice here is what I did.

I buried 52 radials in a circle around the base of the vertical.  I was so excited burying radials I got carried away.

It became addictive.  Here is the initial line-up.

20 radials @ 3ft

10 radials @ 4ft

4   radials  @ 8 ft  

12 radials @ 15 ft

4 radials    @ 16 ft

2 radials    @ 33 ft

I THINK I PUT DOWN TOO MANY.  I WAS IN THE ZONE OF DIMINISHING RETURNS.

Running one hundred watts and an SWR of 1:3

With 4 radials signal reports were: 5&5

With 20 radials various lengths reports were: 5&9

With 33 radials various lengths reports were: 5&9+15

With 52 radials various lengths:  NO DIFFERENCE 

I removed the longer radials and settled for 33.

I was once again talking to the world.  Europe, Central & South America, South Pacific, South Africa all with 5&9 plus reports.

Do I miss the view from the top?  NO WAY.  A SET BACK ALWAYS SET YOU UP FOR A COME BACK. I’M BACK.

How do you put the icing on this cake?  I checked into East Cars yesterday 7255 Mhz.  Jeff NJ2US was net control.  He said that my signal was the fourth strongest on the band. Thanks Jeff.

No matter how old we are.  We always need a mentor.  Don’t be afraid to experiment. 

Always listen to the advice of other hams that have been there, done that, and succeeded.  Emulate success.  The credit for the success of this project goes to a Gentleman I have never met in person.  His name is “BILL” and his call sign is W1ZY.

I came upstairs from the shack this morning with a smile on my face.  The XYL said: “You look radiant this morning.  I hear you talking to your friends on the radio”.  I said: thank you dear.  What can I do for you today? 

Her reply was:  I need new LOW PROFILE tires on the car today and make sure they are RADIALS.

What’s next?  Add some more short radials when the weather breaks.  

Have a look at some of these pictures.