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[Articles Home]  [Add Article]  

Verticals: Got Two?

from Bob Raynor, N4JTE on July 30, 2008
View comments about this article!

Verticals - Got Two?

Or how I learned to build a 2 element reversible 3db gain array on the cheap!
Submitted by Bob Raynor; N4JTE

I have stayed away from verticals for all the usual reasons, mine being I could never get one to work better than a basic dipole despite all the take off angle advantages etc. When my 40 meter EDZ blew down in a heap last week I was desperate to get my 100 watts back on the air in a hurry with some gain and direction capabilities.

Enter my well worn copy of ON4UN's Low Band DXing and chapter 11 on vertical arrays. This time I really read and absorbed the concept of radials and phase lines.

I have been spoiled by the luxury of being able to string up 170 ft. at 65 ft for the EDZ and also construct a 2 element 40 meter reversible quad so I figured why not stay in my own backyard for a change and see what this vertical array thing is all about.

If you are interested in getting a real 3db of gain and the ability to reverse direction instantly in a very small footprint please follow along while this die hard vertical hater learns and shares some new tricks. Also please note that I tried this type of array a few years ago with about 80 radials in the ground and it was an abysmal failure so nothing ventured nothing gained.

The Antenna


(2) 32ft. long insulated wires supported by fiberglass push up masts at aprox. 40 ft. high. Actually only one mast is the push up type the other was scabbed together using various pieces of fiberglass spreaders. By luck I have two existing 4 by 4 posts aligned sort of East/ West and about WL apart or in my case, 32 ft. Seems like somebody wanted me to try a 2 element reversible vertical array.

The secret to my success in this venture was to use raised radials, four on the West pole and three on the East pole. The feedpoint ended up at about 8 ft high so running the radials off to 6 ft. high tie off points, (fence, trees etc.) was no big deal and easily removed if needed. The radials on the West pole are relatively symmetrical but the back pole radials are a little contorted due to lack of available space on my property line.



Construct one element at a time and set for resonance at the frequency of choice by checking for lowest swr, with all radials in place, close enough for our purposes. The ultimate goal is to achieve exact self resonance for both verticals at the same frequency. Start off with the antenna and radials the same length, in my case for 7.185 so they were 32 ft of #14 insulated wire. If you need to adjust for resonance do it by changing the wire vertical part, leave the radials alone for the moment. Note; if you need to make drastic ie; more than an inch or two of length changes then something besides mutual loading is screwing with the settings and you might be getting thrown off by a metal fence or other structures nearby, can't help with that one.

Phase Lines - My other reason for success!


Finally figured out how to use this thing.

I've constructed and abandoned driven arrays, both horizontal and vertical, in the past because I've always felt a dual trace scope was the only way to make the phase correct but there is another way. Stick with me and wade thru the following steps; worth the trouble.

As per ON4UN's well researched specifications you will need 2 feedlines of 84 degrees and one delay line of 71 degrees to achieve the benefits of the Christman method and the force feeding of the two elements which is what gives you the gain and direction switching capabilities. All the 50 ohm coax will be cut to the correct degree length using the MFJ with a Tee connector in parallel with a 50 ohm dummy load.

First determine your target frequency; I will use 7.185 for this discussion. As we need (2) feedlines of 84 degree length it's time for a little theory; A true WL (90degrees) piece of 50 ohm coax will show almost 0 swr at it's electrical length for the frequency of choice when shorted out at the end, FYI, it will do the same at the true wl with the end left open. So we hook up a WL length of coax based on the velocity factor and we are good to go. NOT. Trust me it NEVER works that way. Get the length that way and add a couple of feet. Attach to MFJ and short out the far end and measure for lowest swr and read the freq, in my case a 30 ft. long piece read somewhere around 6.1 megs, way to long. Keep cutting and shorting the far end till you get to the target frequency. An ice pick through the coax is a quicker way. BUT; No matter which method this will give us 90 degrees and we need 84 degrees so it's time for a little math so we can get the correct target frequency read out on the MFJ to make the phase line SWR zero at 84 degrees, before you cut off too much wire!

Formula; 90/7.185 x 84/x = 6.706, gives us freq. readout for 84 degrees.

Verbally; 90 degrees is to 7.185 as 84 degrees is to x, where x is the needed freq on the MFJ.

This method will get you the 71 degree delay line length also. Leave or make all ends bare as you will be hooking the two feedlines to each vertical and the relay and also the 71 degree delay loop to the relay.

Relay Time


PLEASE READ CHAPTER 11-9 Fig. 11-7; ON4UN Low Band DXing for schematic.

Essentially you hook the delay line loop to each of the feedlines at the relay contacts taking care to maintain polarity. In my configuration with the relay off, the loop is leading in the West direction due to the induced phase shift. When 12 volts is applied the loop is now lagging and the direction and gain favors the East. I took a chance and soldered some short hookup wire to the relay contacts for ease of assembly to all the coax feedlines, don't imagine it makes that much of a difference on the phase lengths considering I had to cut off the connectors on the feedlines after using the MFJ for length calculations. My wiring/ soldering hookup was way too nasty to photograph! This design is for 100 Watts so any higher power will of course need a larger relay.

Performance

It always annoys me when I read all these glowing reports from an enthusiastic antenna owner that to me are worthless unless they are well tested at various times and conditions with a couple of other antennas orientated in a similar direction. For my testing I rehung the 40 meter EDZ ladderline fed at about 50 ft. high in an East/ West take off orientation. I also used a North/ South dipole for further comparison. All were connected to a Delta 4 position antenna switch.

The verticals were extremely competitive with the EDZ and as the sun moved West the verticals were 3 S units louder to Ca. and the Netherlands both on receive and transmit.

I did not notice as much noise as expected with verticals unless I went East during the FB barrage here on the East coast at 9pm, I believe that a driven array is slightly less prone to nearby manmade noise.

Some of this may be obvious to the experts out there considering the lower take off angle of the verticals but it was a real revelation to me. I am considering running another set of verticals in the opposite directions using an additional similar setup on a separate switched feedline and perhaps end up with a well functioning poorman's 4square. So many antenna ideas, so little time hi.

Final Thoughts

I believe that any success I achieved with these verticals and none before, was due to using raised radials and cutting phase lines accurately. The added bonus of keeping it all in my own backyard and the simplicity of upkeep and pack up has made this a valuable experiment for me.

I hope this article will encourage others to explore driven arrays and research the amazing amount of reference material out there.

Resources

Relay; Radio shack #IEC255

40ft fiberglass www.shop.dx-is.com

ON4UN's LowBand DXing Book.

Tnx for reading

Bob, N4JTE

Member Comments:
This article has expired. No more comments may be added.
 
Verticals: Got Two?  
by AC5UP on July 30, 2008 Mail this to a friend!
Let's suppose someone doesn't have an analyzer, but they do have some reasonably good coax that's very close to a velocity factor of .66 (or whatever) and a pocket calculator...

In feet, a half wavelength in free space is 492 divided by the frequency in MHz.

Let's use 7.185 as the frequency, so 492 / 7.185 = 68.47599165 --- which is then multiplied by the velocity factor of the coax (let's use .66) = 45.19415449 feet.

Meaning, that's a half wave length of coax with a .66 VF @ 7.185 MHz. How many degrees in half a wavelength? 180. Let's divide the length of the half wave of coax by 180: We get .251078636 feet per degree at the desired frequency.

If you want 71 degrees: .251078636 x 71 = 17.82658316 feet.
If you want 84 degrees: .251078636 x 84 = 21.09060542 feet.

If you don't want to measure your coax to 8 decimal places of a partial foot, multiply the answers from your calculations by 12 and measure the coax in inches... Or, use 5904 (492 x 12) from the start and figure everything in inches.

Close enough?

;)
 
RE: Verticals: Got Two?  
by N2RRA on July 30, 2008 Mail this to a friend!
awesome article! A great response from ac5up. This is what makes me come back to thses forums. Gives me some ideas and going to try this project my self.

Tnx and 73!
 
RE: Verticals: Got Two?  
by W8WLC on July 30, 2008 Mail this to a friend!
Well explained. This is pretty much what I did about 8 years ago when I was heavy into the QRP thing. You see a lot of how-to's on phasing two, three or even four sticks but most leave out how important proper phasing and impedance matching is, resulting in a yard full of metal and a antenna system that is a total failure.
 
RE: Verticals: Got Two?  
by K0BG on July 30, 2008 Mail this to a friend!
Far too often, verticals (phased or otherwise) get a bad rap because folks just don't install them correctly. This includes adequate radials whether it is ground mounted or elevated.

All of the HF verticals I have had were ground mounted, and the last one had nearly 100 radials. It didn't always beat my dipoles, but as you alluded to, there were times when the difference was dramatic.

Alan, KBG
www.k0bg.com
 
RE: Verticals: Got Two?  
by NV2A on July 30, 2008 Mail this to a friend!
Fantastic article. Thanks for taking the time. I've always wanted to do this couldn't find the specifics of it and I'm no rocket scientist either!! This means it might get done after all.
 
RE: Verticals: Got Two?  
by KY6R on July 30, 2008 Mail this to a friend!
I phased two 24' DX Engineering hatted verticals using this exact method and it worked as well as when I have used commercial phasing boxes.

For the switch I had an 8 port DX Engineering switch, and I followed their white paper to be able to switch end fire and broad side:

http://www.dxengineering.com/TechArticles.asp?ID={891C8E97-68E1-4623-9C88-AA3F3EB20EB1}

I used 60 buried radials (stapled to the grass) and LMR 400 to feed. Following ON4UN's method of cutting the phasing lines is VERY important. If you don't cut the phasing lines properly - or just use a calculator, you will be lucky to get it to work "optimally".

I know, I tried that before I really made the array sing! It was amazing to be able to switch broad side and end fire.
 
RE: Verticals: Got Two?  
by KY6R on July 30, 2008 Mail this to a friend!
I have also used a calculator - as AC5UP suggests - to build K1WA arrays. The feedlines are 3/8 wl for the K1WA feeds. The front to back ratio on my Dx Engineering Christman feed verticals is significantly better than the K1WA array (>18 db F/B), and the K1WA array is 12 DB front to back.

But the K1WA array is also very simple - 4 or 5 half wave dipoles hanging off a metal push up mast. For 20M, a 36' push up mast is all that is needed for a 20M K1WA array.

I have also found significantly less noise on either the phased verticals or the K1WA sloping dipole array - because we have many very large high tension power lines around us on nearby ridges. Yagi's and horizontal antennas get swamped with that frying pan noise, and like magic - the verticals (and especially the K1WA Array) makes that noise go away almost completely.

So, in the end, its all about signal to noise ratio. Having direction and gain is the next thing, once you have eliminated your noise source.
 
Verticals: Got Two?  
by WW5AA on July 30, 2008 Mail this to a friend!
What a Great article!...now put a simple RX antenna up and really enjoy..hey maybe I'll do one. Thanks

73 de Lindy
 
RE: Verticals: Got Two?  
by N4JTE on July 30, 2008 Mail this to a friend!
AC5UP; re; close enough, my feedline RG58 is rated at .66 VF the actual feedline length for the 84 degree lines is 24ft. 8ins. Quite differant than your calculations. You do not need a MFJ to get accurate phase line lengths, a tranceiver's swr meter and a 50 ohm dummy load in parallel with the line under test will accomplish the same thing.
tnx for your comments,
Bob
 
RE: Verticals: Got Two?  
by W4VR on July 30, 2008 Mail this to a friend!
Great article, Bob! I wish more authors would include pictures with their articles as you do. That antenna system is the perfect recipe for a guy with a small lot who does not want to spend too much money on a 40 meter antenna. As for me, I will continue to stick with my horizontal wire parasitic arrays on 40 as long as I have at least 1.5 acres of property to play with. If I ever end up with a postage stamp lot, you can bet that I will put up phased verticals!
 
Verticals: Got Two?  
by KL7AJ on July 30, 2008 Mail this to a friend!
Nice work!

Being an old broadcast engineer, I was always very fond of phased verticals. You can improve the performance even further if you have some way of actually measuring the phase angle of the currents in the elements. Both the ARRL handbook, and ON4UN's book have good suggestions on this. You can get extremely high front-to-back ratios with careful phasing....which becomes more critical with a close-spaced array.
If both elements are identical, as in your situation, it does make the whole phasing business a lot simpler.

In an upcoming QST issue, (date to be determined) I have an article "Keeping current with antenna performance" which goes into some detail on measuring antenna currents. Stay tuned!

eric
 
Verticals: Got Two?  
by VE7ASK on July 30, 2008 Mail this to a friend!
Outstanding article -- it's a great project to try if you have a bit of room. I recently used precisely this technique to raise a pair of extremely low-cost wire-only 80M elevated verticals in our pine trees.

The story of that project -- including audio recordings of the verticals switching from east to west end-fire -- is on my website at:

http://www3.telus.net/va7st/array80.htm

-- Bud, VA7ST
 
Verticals: Got Two?  
by K4DPK on July 30, 2008 Mail this to a friend!
Great antenna work and article Bob! Congratulations!

Phil C. Sr.
k4dpk
 
Verticals: Got Two?  
by K7LA on July 30, 2008 Mail this to a friend!
Thanks, Bob.
 
RE: Verticals: Got Two?  
by N4JTE on July 30, 2008 Mail this to a friend!
Ron, W4VR; The day YOU end up on a postage size lot will be the day I put up a motorized 80 ft. tower with a 4 element 40 meter quad, not too likely, tnx for comments.
Bob
 
Verticals: Got Two?  
by WA6L on July 30, 2008 Mail this to a friend!
Well-written and informative article -- thanks!
 
Verticals: Got Two?  
by K9ZF on July 30, 2008 Mail this to a friend!
Great article, really enjoyed it.

I may just have to get out some wire and solder this weekend:-)


73
Dan
--
K9ZF /R no budget Rover ***QRP-l #1269
Check out the Rover Resource Page at: <http://www.qsl.net/n9rla>
List Administrator for: InHam+grid-loc+ham-books
Ask me how to join the Indiana Ham Mailing list!

 
RE: Verticals: Got Two?  
by N8NSN on July 30, 2008 Mail this to a friend!
Great work Bob ! The effort you put into this antenna system, as well as the great details in this article, are both much appreciated. Time invested in details makes the difference between success and failure. Preparation speaks volumes and produces the best result.

TNX and 73,

jimmie KC8BYF
 
RE: Verticals: Got Two?  
by K5END on July 30, 2008 Mail this to a friend!
Nice article, and great pics! That adds so much.

You put some serious effort into this project and it paid.

73
Larry
K5END
 
RE: Verticals: Got Two?  
by K8KAS on July 31, 2008 Mail this to a friend!
Good job Bob. Sometime when you have some time take a look at radial currents in each of the 4 radials, I think you will be very surprised. Only ONE radial will have 95% or more of the current in it with your method of tuning radials, this screws up the overall pattern and greatly lowers system efficency.

To get good radial currents in all the radials you must cut the radials short by 15 or 20% and then feed them (all) thru a series inductor to tune the bunch as a whole. I found this out a long time ago trying to get elevated radials to work as well as the in ground system I was using B4. With out series tuning you might as well use one radial per antenna. Just a suggestion. Denny
 
RE: Verticals: Got Two?  
by N4JTE on July 31, 2008 Mail this to a friend!
Tnx Denny, I will look into that when I get back to NY, next project while I'm here in Miami will be to bungee the push up fiberglass to the truck and run one elevated radial, should be quite a sight.
Take care and tnx for the comments.
Bob
 
RE: Verticals: Got Two?  
by 5R8GQ on August 1, 2008 Mail this to a friend!
An excellent, well written and helpful construction article! Thanks for the great photos, too.
Wish all construction articles were lik this one!
tnx es 73, Ken
 
RE: Verticals: Got Two?  
by NR9R on August 1, 2008 Mail this to a friend!
Thanks for contributing your nice article Bob.

If elevated radials scare people away, one can use a similar configuration for a half square (also described in ON4UN's book). This is a bidirectional antenna which consists of two 1/4 wave elements spaced by 1/2 wavelength. It can be voltage fed at the base of one of the elements with a simple LC cicuit and a few 1/8 wave radials along the ground to provide a current return.

Anthony
 
RE: Verticals: Got Two?  
by N5YPJ on August 2, 2008 Mail this to a friend!
K8KAS said To get good radial currents in all the radials you must cut the radials short by 15 or 20% and then feed them (all) thru a series inductor to tune the bunch as a whole.

Interesting.... I haven't heard this before, then agn haven't seen phased verticals presented in this detail before either -
Can you expound a little bit on this or maybe there's an online reference? Does this also apply to single element verticals?

Thanks
 
RE: Verticals: Got Two?  
by N5YPJ on August 2, 2008 Mail this to a friend!
K8KAS said To get good radial currents in all the radials you must cut the radials short by 15 or 20% and then feed them (all) thru a series inductor to tune the bunch as a whole.

Interesting.... I haven't heard this before, then agn haven't seen phased verticals presented in this detail before either -
Can you expound a little bit on this or maybe there's an online reference? Does this also apply to single element verticals?

Thanks
 
Verticals: Got Two?  
by KE3KR on August 4, 2008 Mail this to a friend!
If you're looking for an 84 degree line at 7.185 MHz, isn't that line going to be 90 degrees long at a higher frequency, rather than a lower one?

7.185/84 = x/90
7.185*90/84 = x
7.698 = x

and same for the 71 degree line

7.185/71 = x/90
7.185*90/71 = x
9.107 = x

or am I missing something?

73,
Chuck KE3KR
 
RE: Verticals: Got Two?  
by N4JTE on August 4, 2008 Mail this to a friend!
Chuck I think you misread the formula; 90/7.185 as 84/x = where X is the freq. readout needed on the mfj or tranceiver.
Bob
 
Verticals: Got Two?  
by KX2T on August 6, 2008 Mail this to a friend!
Hi Bob, great stuff! Really enjoyed your article on the phase verticals on a postage stamp lot. Like yourself I to have had 2 phased verticals for 75mtrs with elivated ground plane on a 50X100ft baack yard with good results. I have since taken that aray down but for any band like 40ty or 20ty this would make agreat limited space antenna project. This article should be the type of stuff we should be rading in QST instead of all the boring articles we see there now. Very good article!!!!
73's Jim
 
Verticals: Got Two?  
by KX2T on August 6, 2008 Mail this to a friend!
Hi Bob, great stuff! Really enjoyed your article on the phase verticals on a postage stamp lot. Like yourself I to have had 2 phased verticals for 75mtrs with elivated ground plane on a 50X100ft baack yard with good results. I have since taken that aray down but for any band like 40ty or 20ty this would make agreat limited space antenna project. This article should be the type of stuff we should be rading in QST instead of all the boring articles we see there now. Very good article!!!!
73's Jim
 
RE: Verticals: Got Two?  
by WA2JJH on August 7, 2008 Mail this to a friend!
NICE!

It would be nice of we got more TECH posts. Too many puff posts these past few months. Glad you spent your time to write a good Tech post.


TNX AGN FER A JOB WELL DONE.

I get decent results with my elevated roof mounted radials and 1 droop down counter poise that is cut for 20M, then another 50 meters of taped loose coiled, large diameter coil.

CB truckers all use co-phased verticals. Many of us could benefit from a antenna system like yours.

I only have space for 2-3 radials for each band I use.

73 DE MIKE WA2JJH
 
RE: Verticals: Got Two?  
by KE3KR on August 7, 2008 Mail this to a friend!
Hi Bob. No, I didn't misread the formula. I stated it so in my post purposefully. I don't understand the purpose of the 6.706 MHz setting for the MFJ. Are you saying in the article that you're making a 90 degree line at 6.706 MHz with the intention of having it be 84 degrees at 7.185 MHz?

73,
Chuck KE3KR
 
RE: Verticals: Got Two?  
by N4JTE on August 7, 2008 Mail this to a friend!
I got the 90 degrees for 7.185, I needed 84 degree so the formula told me what freq to shoot for on the mfj, which is where the 6meg comes from and of course and ended up around 26 ft. I did'nt measure physically any of the lines because I was comfortable shooting for the required length by using the freq. readout at lowest swr for the 84 and 71 line lengths.
I probaly could have cut off 6% of the 90 line but I was more certain this way. Hope that is a little more clear. Works like gangbusters and have to say generaly it is equivilant to the two element parasitic quad I was using quite some time, very surprising.
Tnx for your interest,
Bob
 
RE: Verticals: Got Two?  
by N4JTE on August 7, 2008 Mail this to a friend!
Chuck you are absolutly correct, my formula was WRONG, should have read; 84/90 X 7.185/X or 84 is to 90 as 7.185 is to X, don't have calculator at the moment but it's around 7.6. Thank you for correcting it and now when I get home I will build it again, can only get better.
Thank you big time.
Bob
 
RE: Verticals: Got Two?  
by KE3KR on August 8, 2008 Mail this to a friend!
Hi Bob. I forgot to mention - it's a great article. It sure got me thinking about resurrecting my verticals project here in AZ!

You know, before you rebuild everything, it might be worth remeasuring and modeling what you have now with EZNEC. It sure sounds like your array is performing well, and you might have come up with a useful variant of ON4UN's design.

Thanks & 73,
Chuck KE3KR
 
Verticals: Got Two?  
by N0EW on August 10, 2008 Mail this to a friend!
Nice article and nice to see the good pics. Thanks!

Erik n0ew
 
RE: Verticals: Got Two?  
by W5WSS on August 18, 2008 Mail this to a friend!
Nice article, I am wondering how broad banded the array is. i.e. at what frequency does the directivity drop off to such an extent, where a single vertical equals the performance? I ask this because as we move away from the phase line optimums what measure of drop off in performance would be likely?
 
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