“Why don’t hams like vertical dipole antennas.

See:

http://i31.tinypic.com/160udqb.gif

Elevated Vertical Dipole

Best regards.
Tom
KE6YNH, 73
San Diego, CA

This is the story of how I constructed the ground mount for it.

First a related story…

The day after Christmas my son and I carefully replaced the current copper pipe 16 foot vertical with the pieces from the kit which includes a nifty tilt-base, 4:1 balun and lots of hardware. The details of the actual 43 foot antenna installation will be detailed in another post. For now, I am here to tell a story of how to accommodate the needs of the XYL.

While my son and I were assembling the antenna some 200 feet away from the house it appears the mother-in-law and my wife were not liking what they saw. The wild imagination expressed by by mother-in-law included statements like “It will take five people to carry that thing” and “they should not bend it like that” and “I would not have that in my yard” and, well… sigh.

This got my wife all upset, but her personal concern was actually valid… the antenna will spoil the view. Of course a view with any antenna in it is art to me, but we have spectacular sunsets in our backyard unobstructed by any buildings and my new extension from 16 feet to 43 was going to push her patience. So this article describes how we prepared a new location for the antenna behind the trees, but still in a reasonable location. Lessons learned from the previous installation are applied.

As for my mother-in-law it is quite amazing what folks will say about things they know nothing about to try and let others think they do resulting in everyone knowing they don’t. Foot in mouth syndrome.

Anyway…

When I installed the original pipe in the ground I learned several lessons and continued to hear more good ideas as time went by. Thoughts include:

• Use a 2 inch OD metal pipe for the antenna stake
• Use gravel rather than concrete
• No Weeding

Let’s explore each point in detail.

Use a 2 inch OD metal pipe for the antenna stake
DX Engineering has clamps designed for this diameter – I found black plumbing pipe 1-7/8 inch OD (1.5 inch ID) which seems to be good enough.

Use gravel rather than concrete
This is an idea learned from one of the many ham email reflectors I monitor. I considered using concrete to secure the pipe in the ground, but ran across one fellow in a post who suggested using gravel instead. His thought was gravel will continue to settle and pack ever tighter as the pipe wiggles from the load. His concern about pouring a concrete post hole pier is the dirt could loosen around the cylinder and cause antenna tilt which would be difficult to fix; Indeed a proper concrete pier involves a wide and deep foot which creates more work than probably necessary.

No Weeding
A hard core requirement for this new antenna footing is no weed trimmer to maintain it – mower only please. My old antenna location did pretty well in this regard, but grass did grow “into” the radial plate from the perimeter requiring occasional hand trimming. This time I want to extend the “no growth” zone to well past the edge of the radial plate.

So my son and I proceeded to create the new antenna base for this new vertical antenna.

Resulting in…

Ground Antenna Mount with Antenna Base

The antenna mount is ready and shown with the bottom components of the DX Engineering 43 foot antenna system.

One good idea expressed by a local club member is to define the edge of the circle with landscaping edge material. This will help keep the rocks in and the grass out. This is a great idea and I did just that. Thanks Frank!!

Another good idea is to replace the surface gravel with landscape stone or pebbles… perhaps dark brown. This is a good idea and I will probably do it, but one has to ask how much effort does one put in to “decorating” an antenna mount when the antenna itself remains so obvious.

There is currently only one thing that might be an issue with this mount… the ground pipe easily turns in azimuth. This is not too big a deal with a vertical antenna, but could be a problem if there is some kind of directional antenna on this system. Concrete would certainly solve this. I am not too worried about this issue, but felt it wise to note it.

The final result is I have a new location for the antenna which is more XYL friendly, does not spoil the view of our sunsets and is ready to accept my new 43 foot antenna, ground radial installation and coaxial cable routing.

Stay tuned for upcoming posts.

All three antennas are shown below with the relative currents displayed.

All three antennas at 10 meters

Since 28 MHz is so short, the current profile along 43 feet of vertical radiator is long. The SteppIR BigIR in 3/4 wavelength mode shows a full half wave of current high up along with the 1/4 wave at the bottom. This is, of course, the definition of 3/4 wave. Finally the simple 1/4 wave vertical mode is on the right.

Here are the three patterns superimposed…

Elevation Gain Plots of 43' and SteppIR BigIR

The following characteristics are revealed:

• The 43 foot vertical has its peak lobe at 56 degrees with gain of 5.6 dBi
• The 3/4 wavelength mode of the BigIR has its peak lobe at 47 degrees with a gain of 3.9 dBi
• The 1/4 wavelength mode of the BigIR has its peak lobe at 27 degrees with a gain of 0 dBi
• Suprisingly, the SWR calculated from 28 to 29 MHz was well under 2 and often under 1.5 for each antenna

This comparison reveals each can work at 10 meters, but one has to argue the 43 foot antenna’s angle of radiation is a bit too high for practical use.

The 3/4 wave mode of the BigIR edges out the 1/4 wave mode just slightly at the low angles we desire for long haul DX. Still, who knows, you might gain some benefit from the 3/4 mode if your soil conditions and location are different and the BigIR lets you choose either. Another way to look at the 3/4 mode is a large half-wave radiator is somewhat elevated which may help clear obstacles close by; That could be a serious benefit over 1/4 wave. Pretty nice.

Next time we will analyze the 12 meters band the same way as above and keep going until we hit 160… or maybe just 80.

Stay tuned to your RSS feed.

Trap verticals have been around for decades and many use them with success. However, two new designs have achieved some notice and are attempting to eat into the trap vertical market: The 43 Foot Tuner Required Fixed Length antenna and the Variable Length SteppIR BigIR antenna.

During this shootout we will compare a 43 foot antenna with the BigIR one band at a time. The base model for this analysis will use a ground vertical model from Larry Cebik’s NEC model collection which simulates the benefit of a good radial system. The radial lengths will be adjusted for each band and will be identical for both the 43 foot and the BigIR. The 43 foot vertical will, of course, never change height. The BigIR will be “adjusted” in height for minimum SWR at the test frequency. Where the BigIR can be 3/4 wavelengths height that will be calculated too.

HF Band Analysis:

Band	Antennas		Notes
	43 Foot	BigIR
160 m	1/12 wave	n/a	The Top Band is great, but both antennas are woefully short
80 m	1/6 wave	1/8 wave	Having an 80 meter vertical is worth while
60 m	1/4 wave	1/6 wave	Its nice to have a way to use this new band
40 m	1/3 wave	1/4 wave
30 m	4/9 wave	1/4 wave	WARC bands are often the forgotten bands
20 m	5/8 wave	1/4 wave	This is an important DX band
17 m	4/5 wave	1/4 wave	Another good WARC band
15 m	7/8 wave	1/4 and 3/4 wave	We will compare three antennas since the BigIR can tune 15 m two ways
12 m	17/16 wave	1/4 and 3/4 wave	Ready for sun spots
10 m	5/4 wave	1/4 and 3/4 wave	Ready for sun spots
6 m	9/4	1/4 and 3/4 wave	Just for fun

Note, all the above comparisons have the antennas ground mounted, not elevated.

The big 43 foot next to the BigIR set to 10 meters 1/4 wave

We will analyze each band in turn in upcoming posts and link to them from here so bookmark this page now and stay tuned…

Perhaps he is right for many things, but for ham radio folks evaluating antenna choices a popular answer for the height of a vertical antenna for the HF bands appears to be 43.

Be sure to check out the many posts about the 43 foot antenna here at Ham Help Desk.

If you have been in the market for a vertical you have probably noticed the availability of a “tuner required” vertical which is forty-three feet in height above a reasonable ground plane of radials. Indeed Zero-Five, DX Engineering and others offer this exact configuration in their model lineup claiming “all band” operation from 160 to 10 meters. Can this really be true?

This is also known as a 13 meter vertical. Here is a discussion of why this compromise length exists with some pitfalls.

Forgoing the need for a tuner (which is arguably not too big a deal) let’s have a look at the predicted patterns using EZNec. To set up the simulation, I copied a vertical antenna with four radials from the Cebik model set available for purchase on his web site. The only thing I changed was the antenna height and the radial length.

• Antenna height = 43 feet AGL with the bottom about 3 inches above ground
• Four Radials of 1/4 wave each to simulate an efficient low impedance ground resulting from layout of many radials

I chose Cebik’s vertical example to ensure I leverage his knowledge of how to model radials reasonably well in EZNec which, in my case, uses NEC2 as the engine. NEC2 does not model underground radials so Cebik’s technique is a welcome insertion of NEC2 trickery. Plus, I wanted to capture all the appropriate assumptions he makes for vertical over radials EZNEC antenna simulation.

The antenna looks like this…

View of 43 foot vertical antenna in EZNEC

Now here is the predicted patterns using a typical frequency of the main HF bands. Note the “Primary” trace is the one plotted for the 10 meter band…

Patterns of 43 foot Vertical Antenna on the major HF Bands

The peak radiation angles and relative antenna gain for each bands are:

• ~ 5 dBi @ 57° for 10 meters – impressive, but high angle
• ~ 4 dbi @ 37° for 15 meters
• ~ 1 dBi @ 16° for 20 meters – nice low angle
• ~ 0 dBi @ 25° for 40 meters
• ~ -2 dBi @ 29° for 80 meters – this is quite functional
• ~ -8 dBi @ 23° for 160 meters – lossy, but it does work

Several things are apparent:

• The antenna has “better than nothing at all” performance on 160 meters and is certainly interesting for this difficult band.
• Low gain, but good low angle performance is apparent for 80 through 20 meters.
• The 15 meter band shows some actual gain, but at a high angle of about 30-40 degrees – This may or may not be what we want for our DX purposes on this band. That said, it is noteworthy to see it still has unity gain at lower angles.
• The 10 meter band, the black trace marked as Primary, shows peak energy well above 45 degrees elevation. I suspect this will be less than desirable.

You can see why the ten meter case has the high angle radiation when you look at the currents along the vertical as shown here…

View of 43 foot vertical operating at 28.3 MHz

The opposing current phases destructively interfere at some angles and constructively interfere at others.

Is this an all HF band antenna? Well, because it operates at no particular “tuned” length for any HF band, except maybe 60 meters, you will always need a tuner. So, sure, it can tune up anywhere the tuner (or matcher if you prefer) can match. If you have to have just one antenna for HF, maybe this is a good choice, especially during the current great low band conditions in this low sunspot point in time.

A better reason to consider this antenna is for reasonable 80-20 meter use and as a practical thing to try for the 160 meter band. Because you can tune almost anything to almost any band, it is possible to get 10 and 15 meter use too with the propagation issues described above.

Other advantages for this 43 foot antenna is expense. You can have one for a few hundred dollars and several major antenna manufacturers, noted above, make them. The variables between the manufacturers is likely strength in materials and other mechanical design issues. Look to Eham for evaluations.

In my quest for a do it all vertical to replace my 16.6 foot copper pipe my choices include:

1. Multiband Fixed Height Vertical using Traps
2. Multiband Variable Height Vertical using the SteppIR BigIR III
3. Multiband Fixed Height Vertical using an antenna matcher in the shack – such as this 43 foot concept
4. Multiband Fixed Height Vertical using an antenna matcher at the antenna base – 43 foot concept again
5. Forget the vertical and get a dipole

Because I am getting good results on 20 meters with my 16.6 foot vertical, I am not interested in dipole solution #5… yet. Thus, I desire to bring some closure to this vertical installation and make it the best it can be.

I am still leaning towards the SteppIR BigIR Vertical even though it is a bit expensive. Being able to tune the antenna precisely to the appropriate length is a great feature resulting is little standing waves on the coax.

However, the simplicity of solution #3 means no additional wires to the antenna to power an automatic remote tuner or drive the SteppIR motor. This is just radio (with built-in matcher), coax, antenna. I lose some power in my very long coax with the standing waves, but have a much more reliable system. Uncomplicated solutions are certainly well worth considering.

No matter what your choice, if you want a vertical, consider the investment you will need for the radial system. Get the DX Engineering Radial plate and just do it. It really helps.

One more point is worth mentioning. The various makers of 43 foot vertical antennas all suggest the use of a 1:4 balun. Some suggest using a balun model made specifically for “tuner use” with the idea these specialized units have the robustness needed to handle the less that ideal voltages and currents. A nice balun costs good coin and is certainly worth it. Just be sure to roll this expense into your trade study when comparing this 43 foot solution with something like the BigIR vertical.

Also watch out for aluminum components near the ground. Certain soil conditions will dissolve aluminum.

DX Engineering and Zero Five Antennas seem to be in hot competition in the vertical market and they both have an approximate 43 foot system to sell you. If you are in the market for this kind of vertical start your trade study with these two manufacturers.

Good luck.

Well, to be honest you may well have just as much success with a simple horizontal dipole strung up.

Dipoles are pretty easy to build and don’t cost too much if you would rather purchase one from Alpha-Delta or the Wireman.

However, if you…

• don’t have trees to support your dipole
• already have a dipole, but are interested in seeing if a vertical provides more performance
• have no antenna, but lots of property to try something new
• just want to try something different

…then this simple vertical antenna is for you.

The description on its construction are contained within the pages of…

It is nothing more than several sections of copper plumbing pipe available at any hardware outlet such as Home Depot, Lowes, etc.

The key to any practical ground mounted vertical antenna is radials, radials and more radials. I choose the radial concentrator plate from DX Engineering to organize my radial attachments. In my case each radial is 33 feet long, but since this is ground mounted, the radials are not tuned which means the lengths are not super critical.

I buried the coax between the house and the antenna.

As you can see…

16 foot vertical antenna over radial wires

…this antenna has a simple appearance. However, it works quite well on 20, 17 and 15 meters. I have a few 10 meter contacts too, but this is arguably the wrong band for an antenna cut for 20 meters.

Soon I will be putting up a dipole too since I actually do have a few trees of modest height. I am considering the Alpha-Delta DX-CC as a friend of mine has a large log from his. Plus, this will get me on 40 and 80 meters which is, at this point in the solar cycle, a good place to operate.

When I have both antennas I will do some simple AB comparisons asking:

• Does the vertical receive more noise as everyone suggests it might?
• Does the vertical provide better low angle performance?
• Does either antenna provide a benefit for certain bands and distances?
• Is a replacement vertical radiator such as the continuously tunable SteppIR BigIR vertical or the “tuner-required” 43 foot radiator several companies are selling something worth considering?
• Assuming I get a vertical with more bands along with the dipole DX-CC am I done with antennas for my QTH?

One of the things I love about ham radio is exactly these kind of choices.

Even though my radials are good and plenty, I realize the low angle performance is more reliant on the local soil conditions up to many wavelengths away from the antenna rather than anything I do with my radials. Still radials are there to ensure your antenna efficiency is good so you still should have plenty. Look up the excellent details on Cebik’s web site for more information before you try to understand what radials do for vertical antennas.

If you desire to try a vertical antenna, consider this simple copper pipe version. It is cheap, but does require quite a bit of radial wire. However, if you like what you get with your vertical antenna and want to upgrade to something better, the investment in your radial system will translate right over to your new antenna… and that antenna will love you for it.

UPDATE 2009:
I made my first, and so far only, Phone contact with Australia using this antenna on 20 meters. I was thrilled. This suggests simple antennas do work. However, I do admit the quad array of 20 meter beams used by the Aussie were the significant factor in our QSO

For some while SteppIR has offered two vertical versions of this adjustable length antenna: one for 6-20 meters, the other 6-40 meters. Also, an optional base load coil option is available to extend band coverage to 60 and 80 meters.

The web site…

…offers an excellent view of what is inside the control boxes of the BigIR Vertical and the 80 meter coil.

You get an instant appreciation of how SteppIR Antennas, Inc. has addressed how to make an antenna element move in and out in an almost infinite number of positions using a stepper motor.

The 80 meter optional coil is also a clever way to extend the capability of this antenna to the lower bands albeit with compromised performance indicative of any “electrically short” radiator. This is, of course, due to antenna physics, not anything SteppIR Antennas, Inc. did.

The manufacturer’s web site…

…also shows a photo of the inside, but which does not immediately reveal this is a custom PCB switch using a PCB .

The 80 meter option assembly is very large and I began to wonder why.

Because the 80 meter option is a tapped inductance, as clearly shown in the photos contained in the web site referenced above, one might consider using high quality RF switches or relays to select the amount of inductance. A switch to bypass the coil entirely when using the SteppIR BigIR for 40 to 6 meter work is also sensible.

What the photos on the web site above made clear is SteppIR Antennas did not use RF relays to perform the select-coil-tap function, but manufactured their own switch using printed circuit boards arranged in a rotating contact switch operated by a stepper motor. Obviously, they are capitalizing on the great experience they have with stepper motors and the way they control it with their desktop controller.

As noted by the fine folks on the SteppIR email list, the coil taps have potentially large voltages that could easily arc over relay contacts when operating at higher powers.

My original version of this post forgot this important point. Now I understand why SteppIR went to such trouble to produce a very large switch with large separation between the “contacts” to handle the high voltages present. The cuts in the PCB material between each switch contact point reinforce this point.

The list of the issues with the 80 meter coil option include:

• Home-Brewish Inductor Tap Switch – The flimsy nature of this system still begs for a better approach, but I have to admit I cannot think a better approach in this price class
• Stiff wires on the moving switch contacts produce stress – high strand count wire may make better sense
• Weather exposed terminal connections for the stepper motor wiring – a good connector approach would be an option I would gladly pay extra for
• PCB trace-widths may not handle full power at the the 1,500 watt rating especially with the higher currents feeding the lower impedance of a short monopole. My calculations for 10 °C rise for the currents expected into, say, a 25 O antenna start at 0.1 inch with 2 oz. copper thickness. The PCB board has ample room for wider trace widths.
• Power off default potentially undefined

Soon I will post some details of suggested improvements to take SteppIR’s brilliant thinking into a better engineered approach.

A purchase of the BigIR vertical is a certainty for me. The enormous 80 meter option is a reasonable value at under $400 and would be a for-sure purchase if it wasn’t so large and I had not seen the inside home-brew switch. Still, the high voltage tolerance of SteppIR’s unique rotating PCB switch is, perhaps, a clever affordable solution that brings a good solution at a good price point… nothing wrong with that.

In SteppIR Antennas’ defense, product development can be quite a pain, especially when targeting products for notoriously stingy hams. The fact they have products for us to buy with their unique twist is a good thing for amateur radio.

To highlight their cleverness this is a best guess schematic of the RF paths…

The RF Paths in the SteppIR BigIR 80 m Option Coil

The most interesting portion of this schematic is the wiring of the coax wrapped toroid. It is another clever SteppIR design feature that helps match 50 ohm coax with the ~ 14 ohm impedance of a series inductance base loaded monopole antenna.

You are doing a good job SteppIR Antennas. With a few tweaks you will have a near perfect product. On the other hand, for the price you just might already have a near perfect product.

SteppIR, please take note… I would be delighted to pay another $100 for a good weather proof connector for the motor signals.