Questions about Radials

[k1asc]

Greetings,

I am not an electrical engineer so I won't pretend I understand everything about the topic but...

Imagine you're putting down radials for a vertical and real estate is *very* limited.

Is it preferred to lay down your radials in a specific pattern? Can radials be laid down in right angles...(as long as they're evenly spaced). The "straight line" approach in this case is the most effective, right?

80 meters radial is about 64 feet long (I hope I got the number right http://www.qrz.com/iB_html/non-cgi/emoticons/rock.gif ) so since real estate is a problem, is it acceptable to neatly coil up the leftover cable?

I welcome any advice...as long as it does not involve relocation http://www.qrz.com/iB_html/non-cgi/emoticons/wink.gif

Thank you and 73,

Al.

[kl7aj]

Any radial is going to better than none. Put down what you can, get on the air, and don't worry about it.


Radials are like radon gas....something to give some people something to wring their hands about, while others are actually accomplishing something.

I'd prefer the latter group. http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif

[K0RGR]

First of all, if you're doing this on or in the ground, the radials don't need to be cut to 1/4 wavelength - they can be substantially shorter. 50 feet ought to be good on 80, 25 on 40. A lot of even shorter ones will work.

A lot of short radials is much better than a handful of long ones. "A lot" is more than 20.

They can be bent in any shape you like - some people have buried beds of chickenwire - we tried that once and it worked fairly well! We've also used the neighbor's chain link fence to great advantage.

[k1asc]

Guys,

Thanks for the replies. I am obviously over-thinking all this.

Thanks again.

[kl7aj]

Quote[/b] (k1asc @ Oct. 03 2007,11:35)]I am obviously over-thinking all this.
This is a VERY common new-ham malady, which I SPECIFICALLY address in the following chapter. Enjoy!


Eric



CHAPTER SEVEN

First You Make it Work;
Then You Make it Pretty



A lot of new hams are susceptible to putting the cart before the hearse...er...horse. Your first “job” as a ham should be getting on the air and actually communicating with someone...and making a few mistakes in the process.
If you are like most of the current breed of new hams, you have been assaulted with all kinds of conflicting and contradictory advice, and no clue as to how to sort it all out. First of all, let me assure you, it’s not your fault. For the past generation or so, we have been invaded by marauding armies. Oddly enough, these are not Barbarians, Vikings, or even Communists. No, they are far more despicable than all three combined. These frightening aliens come under the name of “Professionals.” These are people who perceive their calling in life as doing your thinking for you. These compassionate souls want to take all the risk, uncertainty, and danger out of your life. In other words, they want to remove the fun from your life. They want to organize you, schedule you, and spoon-feed you regurgitated information. You’re probably already getting enough of this from your job. The very last thing you need in your life is for ham radio to become another job. (Now, ham radio may very well prepare you for a job, as we will discuss in detail in another chapter, but it should never become one.)
Once you recognize these “Professionals” for the true villains they are, your life will become so much simpler. Having an Elmer, as mentioned earlier, will go a long ways toward keeping your sanity through your “ham infancy.”
Now, I have been licensed for going on 40 years, and I learn something new from ham radio every day. Nobody is a greater advocate of getting an education from ham radio than yours truly. But that is a whole different thing than expecting to know it all before you get on the air! Yes, you certainly want to know enough to be legal; it’s no fun getting a “QSL” card from the FCC your first day out of the chute. And you don’t want to be known as a complete lid, even if you are officially legal. But none of these considerations should EVER stop you from getting on the air, making a lot of contacts, and having fun. You’ve already worked too hard to get here to accept anything less.
Now, throughout your ham radio career, you’re going to get some bad information...it’s inevitable with any hobby of this magnitude. Unfortunately, some of this misinformation seems to take on a life of its own, reproducing itself with incredible efficiency on the amateur bands.
What we will do in this chapter is give you the basic tools to determine all by your very own self if what someone tells you is true or not, when it comes to amateur radio “information.” If you pay close attention, you will never be at the mercy of some Professional’s opinion. The nice thing about this is that it applies to your world outside of ham radio, too!
Principle 1) All information is subject to experimentation.
It is truly staggering to hear many hams argue for years...or decades...about some pet amateur radio topic, and never EVER bother to try out the thing and see. Amateur radio is a scientific hobby, above all else. There are ways to prove or disprove electronics principles. Most controversies can be settled by a simple “Let’s build it and see.”
Principle 2) The repetition of bad information does not make it good information, no matter how often the process is repeated. This would seem to need no further explanation, but experience tells us this is not the case. So, this statement itself bears repetition. The repetition of bad information does not make it good information, no matter how often the process is repeated.
Now, THAT is something I can guarantee is GOOD information! Remember it! (And feel free to repeat it as necessary).
Principle 3) Assume everything you hear is a lie. Now, at first blush, this may seem to be the formula for cynicism. Actually, it’s the formula for progress. All increase in knowledge occurs when things “everyone knows” are questioned. The beauty of this is that experimentation usually proves Principle 3 to be the case. Of course, you should be open-minded enough to admit when some past truth actually DOES turn out to be true.
Principle 4) No information at all is usually better than the wrong information.
This one bears a bit of dissertation, with a real world example.
In the early days of radio, very few amateurs had any decent test equipment. Usually the only indication that their station was working at all was the fact that they were talking to someone across the country, or on the other side of the globe. Modern hams could probably take a cue from this. To paraphrase: “If it ain’t broke, don’t fix it.” The fact of the matter was that thousands of hams successfully talked around the world for decades without really having a clue what they were doing. “Whatever Works” was the order of the day. It wasn’t always pretty, but nobody cared. Radio communication was random, unpredictable, unfathomable, and totally wonderful, for precisely those reasons.
Antennas were probably the least understood part of any ham shack. They generally consisted of whatever pieces of wire one could put into the air. Coaxial cable hadn’t even been invented, or even remotely thought of. In fact, most hams didn’t use transmission lines at all, and if they did, it usually consisted of open wire feed line of any convenient spacing. Antenna theory as we know it didn’t exist. Some cutting-edge hams had a vague idea of this thing called “resonance,” but didn’t really know how to implement it.
And yet, they worked the World.
Nowadays, the situation is pretty much reversed. A typical newly-licensed ham has more sophisticated radios and test equipment at their fingertips than the National Bureau of Standards had in the 1950’s, and yet can’t manage to get a signal out of his basement. What has gone wrong?
What has basically gone wrong is that we now have all the correct answers to the wrong questions! For example, most new hams are absolutely obsessed with this thing called SWR (or VSWR). If you haven’t heard of it, trust me, you will. SWR only became an issue when coaxial cable became commonplace. And yes, there is a certain importance to having a reasonably low SWR when using coaxial transmission lines, but for entirely different reasons than normally cited. Before coax cable became fairly universal, most hams had no way of even measuring SWR, even if any of them even had a reason to care...which they didn’t. And, and even if they did, in many cases a low SWR would have been highly undesirable!
SWR is like Radon gas. It’s just something to worry about while other people are accomplishing things.
Principle 5) You’re a lot smarter than you think. Never be intimidated by professionals or experts. They weren’t born that way. All they can really do is give you reasons why what you’re doing can’t possibly work.
Make it work, then, and only then...if you find it absolutely necessary to please some perceived expert...make it pretty.

[AG3Y]

Quote[/b] (K0RGR @ Oct. 03 2007,15:27)]First of all, if you're doing this on or in the ground, the radials don't need to be cut to 1/4 wavelength - they can be substantially shorter. 50 feet ought to be good on 80, 25 on 40. A lot of even shorter ones will work.

A lot of short radials is much better than a handful of long ones. "A lot" is more than 20.

They can be bent in any shape you like - some people have buried beds of chickenwire - we tried that once and it worked fairly well! We've also used the neighbor's chain link fence to great advantage.
Chicken wire will turn to white powder in about a year or two, if your soil is the least bit acidic. You are far better running as many short lengths of regular copper wire to the edge of your property or util they run into the foundation of your buildings, etc.

As stated, many short radials will do a better job than fewer longer ones. The most important region to get low RF resistance in, is the area closest to the feedpoint and the ground return so the currents have as great a chance as possible to be "balanced"! Unbalanced RF currents create a "common mode" current on the outside of the shield of your coax, and that is why you experience "RF in the Shack"

Good luck! 73, Jim

[n2lk]

For what its worth my 6BTV Hustler works well on all bands with 22 radials, none longer than 30 feet. Most are 16 ft. and a couple of 11 and 8footers. i have a real small lot and have nice tuning on 10-80 meters. Plenty of DX too, and on 80M!!

Lay whatever you can down, bend if need be and go pollute the ether..
73
N2LK

[k1asc]

Wow!

Luck would have it, I am putting up a 6BTV Hustler too.

That is great input to have. Thank you.

[kr2c]

I have a 6BTV. It wasn't very good with no radials. Work good with 20 radials and even better with 40. 60 radials didn't seem to make too much difference to me though. The first 20 radials were tuned to the bands I wanted to work. It's a ground mounted installation and I didn't know any better. The rest of the radials are 30 feet each. The antenna seems to do well with DX and cross country stuff. I have trouble with the real close in guys though.

[VK3PA]

Having played with my full size triangle phased array on 80/75m i found that if the radials are less than 60 plus the swr of the antenna changed when wx was very dry to very wet.. I now have 108 underground radials per vertical es all are 1/4 wave long on 80m.. I now find no differance in swr between wet or dry ground. thats a total o 318 gnd wires.. hve 260+ comfirmed on 80/75 so extra work on the radial system is worth the extra work. http://www.vk3pa.com/Picture/igallery.asp

[K3VR]

I use a ground mounted Hustler 5BTV in addition to my beam. It works extremely well on 80-10 meters with 50 radials cut to 16 feet each. DX Engineering manufactures some great accessories for the BTV antenna series. I use their ss radial plate; coax pig tail; tilt over fixture; saddle clamps; and they also sell Penetrox. #My soil conductivity is 4 (not great). You'll do better using more radials in areas with poor conductivity, but if you ground mount your antenna, radial length is not critical.

12 radials cut to 31.2 feet (or .1 wavelength) on 80 meters will give you 65% efficiency. You'll need 100 radials to approach 90% efficiency. Like I said, mine are only 16 feet long and they work great, even on 80 meters. Read the ground radial tutorial from SteppIR, starting on page 16.

SteppIR Manual (http://www.steppir.com/files/biggir%20instruction%20manual%2024%20pages.pdf)

Hustler Vertical Installations (http://www.dxengineering.com/techarticles.asp?ID={C9555CF0-A9E8-4E59-826E-E53C85015B21})

Soil Conductivity Chart (http://www.fcc.gov/mb/audio/m3/)

[w2rdt]

I have a 5-BTV and was in the same boat for space.
Today, finally, I have 10-40 meters down to 1.1 to
1.4 on swr. My 80 meter is still wacky, low side is 1.4
high side is infinity. I have 4 62 1/8 th radials set and
they are all in a zig-zag design. all I need to do now
is adjust the antenna.
For BTV owners, Mike at DX Engineering sent me a
picture of a 40 meter coil to install on the base of the
antenna, it was simple to make and easy to install/
This brought my 40 meters down to 1.1 to 1.3. with
98 % efficiency.
After setting all radials to specs for length, I am
going to run some more radials around 25 feet.
If anyone is interested in the coil instructions I will
be avaiable. ALSO, The traps on these antennas are
tuned for the area where they are manufactured, Mike
also sent me the instructions to tune the traps for
optimal performance in my area. This was a great
help, I got near exact flat swr thru all the bands
after tuning the traps.
This is a great antenna, touchy to tune but well
worth the effort.
73s--Russ==KC2RKO

[N8MME]

Quote[/b] (k1asc @ Oct. 03 2007,11:16)]Is it preferred to lay down your radials in a specific pattern? Can radials be laid down in right angles...(as long as they're evenly spaced). #The "straight line" approach in this case is the most effective, right?
Radials, just as with bias-ply tires, should definitely be at right angles to the ground. Be sure they are evenly spaced...no wider than the axle. And it is always preferred that they are in a straight line with the path of travel.

Ooops...wrong forum. Sorry.

[k6jpd]

i also have a ground mounted (15 inches above ground) BTV and i have 3 500 ft spools of wire in the ground on a small lot.
tuning the radials doesn't seem to really matter (for me) as the ground "de-tunes" them anyway.
a gas powered sidewalk edger makes nice slits in the ground, just lay the wire in the slit.

[kl7aj]

Quote[/b] (N8MME @ Oct. 05 2007,06:33)]Quote[/b] (k1asc @ Oct. 03 2007,11:16)]Is it preferred to lay down your radials in a specific pattern? Can radials be laid down in right angles...(as long as they're evenly spaced). #The "straight line" approach in this case is the most effective, right?
Radials, just as with bias-ply tires, should definitely be at right angles to the ground. #Be sure they are evenly spaced...no wider than the axle. #And it is always preferred that they are in a straight line with the path of travel.

Ooops...wrong forum. #Sorry.
There's a clown in every crowd, isn't there. http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif http://www.qrz.com/iB_html/non-cgi/emoticons/biggrin.gif

[k8jd]

Quote[/b] (k1asc @ Oct. 03 2007,18:16)]Greetings,

I am not an electrical engineer so I won't pretend I understand everything about the topic but...

Imagine you're putting down radials for a vertical and

80 meters radial is about 64 feet long (I hope I got the number right http://www.qrz.com/iB_html/non-cgi/emoticons/rock.gif ) so since real estate is a problem, is it acceptable to neatly coil up the leftover cable?

Thank you and 73,

Al.
No! stretch as much of the 67 ft radial straight as possible and cut it off. Use the remainder for another straight radial for a higher band.

[k4kyv]

Use as many radials as you can, and run them as long as you can.

Many short radials is better than just a few long ones.

Once you pass about 60 quarter-wave radials, you reach a point of diminishing return. The more you add, the less effect each new one has.

I have the space and acquired a 16,000 ft spool of wire a couple of decades ago, so it cut it up into 120 quarter-wave radials for 160, and installed them around a 127' tower on a base insulator. But I suspect I could have used half that number and the difference in my signal would have been undetectable.

But as I always say, "Better to have it and not need it, than to need it and not have it."

[kl7aj]

Quote[/b] (k4kyv @ Oct. 07 2007,23:01)]Use as many radials as you can, and run them as #long as you can.

Many short radials is better than just a few long ones.

Once you pass about 60 quarter-wave radials, you reach a point of diminishing return. #The more you add, the less effect #each new one has.

I have the space and acquired a 16,000 ft spool of wire a couple of decades ago, so it cut it up into 120 quarter-wave radials for 160, and installed them around a 127' tower on a base insulator. #But I suspect I could have used half that number and the difference in my signal would have been undetectable.

But as I always say, "Better to have it and not need it, than to need it and not have it."
Here's a way to KNOW if your radials are doing you any good....there are actually some cases where adding more radials may be COUNTERPRODUCTIVE.

But...here's the bottom line. Beg borrow or steal (or build!) SOME kind of R.F. ammeter. Doesn't have to be calibrated, just has to be sensitive and relative. MEASURE the current in the vertical part of your antenna. Anything you do to your radials that INCREASES that current is helping you. If you're not seeing a measureable increase in antenna current, you have enough radials. Simple and honest.

eric