So…

I have been eagerly absorbing all there is to know about the hex beam style of HF antennas.

If you are the least bit interested in building or buying your own hex beam a must read web site is the G3TXQ study of the hex beam…

One word that comes to mind is “WOW” what a great collection of tests, simulations and other thoughts about the hex beam.

My favorite feature of the site is the availability of an EZNEC simulation file for the G3TXQ of the five band broadband hex beam.

I eagerly downloaded the EZNEC file and, because I have the + version of the software with a higher segment limit, changed all the wires to a consistent and even segmentation rather than keeping the tapering feature. I now have 1223 segments in the mode. It takes a lot longer to do simulations, but is no big deal.

What I am doing with this beam is for another post. The question I hear often on the hexbeam Yahoo forum is concerning using the five band hex on 6 meters.

The focus of concern comes from the third harmonic of the 17 meter element which is close to the 6 meter band.

Indeed running a SWR plot on the stock five band hex beam between 48 and 56 MHz yields…

SWR of Five Band Hex Beam for 6 Meters

Hmmm, this is not a fantastic SWR, but sure suggests something in the five band broadband hex beam is absorbing the energy. Let’s see where the currents are…

Current Magnitudes in Five Band Hex at 51 MHz

Sure enough, the 17 meter element has the most current suggesting it is providing the majority of the absorption at 51 MHz. If you look closely, only the driven element has lots of current while the reflector seems quiet. If you look closer still you can imaging the 17 meter M element acting a bit like a folded Extended Zepp antenna. An examination of current phase indeed confirms that center current peak is of opposite polarity than the current peaks at the ends.

So this is all very interesting. The stock G3TXQ Broadband Hex Beam sort of works on 6 meters. Even if you can live with the high SWRs, is the pattern useful? The next figure shows the Elevation pattern of the five band hex beam up about 20 feet above the same ground as defined in the original G3TXQ file…

Elevation Pattern of 5 Band Hex Beam at 51MHz

Hmmm, not too shabby. Remember to not get too excited with gain figures of 8 dBi when simulating antennas above real ground; There is often a gain increase due to ground for any antenna including simple dipoles. The point here is this HF antenna seems to offer some gain at 6 meters. Here is the Azimuth plot of the 12 degree elevation…

12 Deg Azimuth of 5 Band Hex at 51 MHz

The front to back and front to side ratio is a bit weak at 5 dB, but this is certainly a directional antenna at 51 MHz.

My ultimate goal is to build a contest version of the broadband hex beam for just 20, 15 and 10 meters. After I deleted the 17 and 12 meter wires from the model, I ran SWR again to see if things change at 51 MHz…

SWR of 5 Band Broadband Hex Beam at 6 Meters

They sure did. The 12 and/or the 17 meter elements were certainly contributing to the dip in SWR in the 6 meter band. It is pretty obvious the 17 meter wires were operating at the third harmonic so I rule the 12 meter wires are not contributing to 6 meter operation.

So… what does the mean?

Two things.

1. If you have the five band 20-10 meter G3TXQ Broadband Hex Beam antenna, you may well have a workable 6 meter antenna too. If your rig has 6 meters on its HF output and a built-in auto-tuner, press TUNE at 51 MHz and see what you get. You may well have a free 6 meter beam ready for use.
2. Adding an additional 6 meter set of wires to the existing 5 band HF G3TXQ Broadband Hex Beam antenna, may be a waste of time since the 17 meter element is competing for some of the energy at 50+MHz.

The second point may surprise many folks who have invested in adding a 6 meter element to their five band hex beam. They say “it works fine.” That’s great, but it certainly is worth knowing why. In a future post we will simulate the five band with the extra 6 meter wires and see what we find.

Given the above facts, I will never add a 6 meter add on to the current G3TXQ Broadband Hex Beam design as it is clearly competing with the 17 meter antenna.

However, remember, I am building a three band hex beam with 20, 15 and 10 meters. This antenna won’t have the conflicting third harmonic issues caused by the 17 meter portion. I will explore the reasonableness of add 6 meters to my three band configuration in a future post.

Conclusion

For those of you with the 5 band design, you may well have a workable 6 meter beam an autotune button away from use right now. Give it a try and let us know the results by adding comments to this post.

There is an obvious conflict between an added 6m wire set and the existing 17m wire set which may create a complicated situation which looks “good enough,” but may be not what you expect. I would love to post your far-field 6 meter measurements of relative gain, front-back and front-side ratios. Please, no comments about how the hex beam is impossible to simulate.

Kudoes

I can’t thank G3TXQ enough for his extensive research into the hex beam antenna and his Broadband alternative. I very much look forward to building my contest version leveraging his excellent work.

Summarized, we were trying to set up APRS relay stations up and down the east coast to cover and service all points along the Appalachian Trail and surrounding areas. Some RF link analysis was performed and is available for viewing at http://www.packetradio.net/events/AT_Golden_Packet_Event/ using the remarkable Radio Mobile program and A LOT of SRTM elevation data.

Of the fourteen stations planned several points were accessible only by foot. The White Rock Cliffs station was no exception.

So an all-call was put out for fit hams to assist in the planning and execution of placing a temporary APRS digipeater system on the cliff face of White Rock Cliffs to yield the northbound and southbound RF links. Some interest was expressed, but, in the end, kx4o and kj4faj were the only two hams to volunteer.

Preparations for Station 6 are outlined at http://www.packetradio.net/events/AT_Golden_Packet_Event/stations/station_06.html. Highlights include:

• Enlist the aid of non-ham hikers to build up the team to safe levels
• Get a trail map of the area
• Obtain a Kenwood TM-700 or 710 APRS VHF/UHF radio
• Build a cool antenna that has some gain and can be hand carried
• Get some modern backpacks with water delivery systems

More Hikers

Several folks at work seemed to be in good shape and expressed interest in outdoor activities. I asked two who are new to the area if they would like to hike and learn about trails west of the Northern Virginia area where we live. Two accepted the challenge: Rob Searle and Jay Gundlach.

Trail Map

White Rock Cliffs is at the end of a short pipe-stem trail off the “Big Blue” trail on the border between West Virginia and Virginia. I am just as unfamiliar with this trail system as my new hiker recruits. I did not hesitate to purchase the trail Map F authored by the PATC.

Obtain an APRS Radio

Thankfully, the Golden Packet organizer loaned me a radio for this event. I like it so much that I am now in the market for a TM-710A.

Portable Antenna with Gain

The Golden Packet event is unique in that each station has to focus their efforts on just two directions: link to the next station north and a link to the next station south. Some are using two beam antennas with a power splitter/combiner. Since we had to hike our equipment to the White Rock Cliff’s site, I wanted to concentrate on a simpler omnidirectional antenna with engineering to realize higher gain in all directions. Several approaches were considered:

• Simple quarter wave GP or half-wave J-Pole – Discussed here
• 5/8ths wave J-Pole – Compared here
• Collinear J-Pole – Compared here
• Collinear 5/8ths wave J-Pole – more copper than it is worth
• 5/4 Wave Vertical – Debunked here
• Rubber Ducky Antenna – Not really considered, but is certainly an option

In the end the collinear half-wave J-Pole was the one that simulated best.

EZNEC Currents in 2M 1/2wave J-Pole

I am thankful for programs like EZNEC that allow one to get a rough order look at new antenna topologies and quit guessing. There seems to be a popular notion antennas that provide a good match to the coax for low SWR perform quite well as a radiator. If you have not already noticed, dispelling this myth is a chief goal of Ham Help Desk.

Anyway, as you look at the Half-Wave Collinear J-Pole antenna in the right figure you can see how the lengths were adjusted until the peak currents were centered in each of the two vertical sections. It is a bit hard to see, but sections #1 and #5 form the two half-wave radiation conductors. By the way, all of these conductors are simulated with 1/2 copper pipe – the material used for this antenna. The bottom sections, #6,7, and 8, form the J of the J-Pole and are essentially a half-wave total length. Sections #2, 3 and 4, form the all important 180° delay section to ensure the top half of the antenna radiates in phase with the bottom (rather than out of phase like the debunked 5/4 Wave antenna).

A future post will go into more detail about this antenna. For now, know that we procrastinated and did nothing for this antenna until the very weekend of the Golden Packet event (a Sunday). All parts were purchased on Saturday morning, pipe cutting and soldering performed on Saturday night, test assembly and tuning done on Sunday morning (real early) and hauled untested to the mountain top Sunday midday. Folks, this is not the way to live your life, but EZNEC predictions seemed to work just fine.

Collinear J-Pole

All the antenna pieces breakdown into backpack size items with the exception of the two radiator elements. These two pieces are carried by hand with ease by the hikers. If desired, the radiator sections can be split with a coupler soldered to one of the pipes to allow all pipes to fit inside a backpack. I decided against this for now as I was not sure how flimsy this contraption would be on a windy mountain top.

Did we really need a complicated antenna with a view like this?

Antenna's view south

KJ4FAJ 'Texting' to GDHill (#8)

Here are kx4o and kj4faj learning how to use the Kenwood TM-700A radio…

KX4O & KJ4FAJ

Rob Searle, the most athletic of our foursome, poses with the antenna…

Rob with Collinear J-Pole

Kudos

“Thank you” cannot be said often enough for the help provided by Rob and Jay during this Golden Packet hiking “mission.” They both are clearly active people. They and my son are in far better shape than me as they often would climb the hill at a faster pace that I could possibly hold. It worked out well though. Jay provided help with navigation using the essential Map from PATC, Rob hauled my pack part of the way up the hill giving me a needed break and both located rock overhang cover in case we needed to hide from the nearby thunderstorms.

Jay Gundlach (bottom) and Rob Searle - Essential Crew atop White Rock Cliffs

Thanks also to the SkyWarn Network working out of the 147.300 repeater who, as soon as they knew we were near local thunderstorms, provided updates to alert us of impending danger. We had lightning nearby, but it never came… too close?!?!?! We were ready to dive into the rock shelter located by Jay and Rob at a moment’s notice.

More Pictures

The view towards Maryland - can you see the upper half of the antenna?

The White Rock Cliffs Golden Packet Crew 2009

Jay, Rob and KJ4FAJ resting during descent - they were actually waiting for me to catch up.

Final Thoughts

• The PATC Trail Map was essential to get us on the right path in the beginning of our ascent – well worth the $6 plus shipping.
• Having “real” hikers as part of the group was essential to bring proper experience to the crew.
• I busted my butt in the Gym the last two months preparing for this, but still have a long way to go when I compare myself to the in shape hiking peers.
• I made several 146.520 MHz simplex contacts plus hit my Warrenton home-town repeater with ease.
• I contacted Bob Bruninga, the organizer of the Golden Packet Test, on two different repeaters and I got confused at first because I was, at first, barely hearing one of the repeaters. I quickly realized I was hearing another repeater on the same frequency much farther away.
• My son and I purchased new backpacks for this event. The new packs offer a place to store a good supply of water fed to the hiker via a convenient tube. Nice.
• One 7 amp-hour gel cell powered the whole event just fine. I was skeptical at first, but am now a believer. We brought two 7 AH cells just in case, but did not need the second one.
• I am reasonably happy with the Hiker Collinear J-Pole, especially after the short build time, but hope to refine it a bit. That’s for another post on HHD.

This was a fun event and I hope to repeat it again next year.

John
de kx4o
Future non-fat ham.

One response included a link to this web page showcasing a collinear J-Pole antenna using two 5/8ths wave antenna elements.

As soon as I saw the site I thought, “Oh no… not another 5/8th wave antenna discovery.” However, to my surprise (and very much unlike the regular 5/8ths J-pole which does not work well at all) the two 5/8ths sections yielded a reasonably symmetrical pattern in both free-space and over real ground at a similar height. Feeding issues aside, at least this design passes the threshold of physics.

So let’s compare the relative merits of the 5/8ths collinear J-Pole by first introducing the contenders…

Three J-Poles for this Simulation

I added a regular J-Pole to compare each collinear design against.

The free-space simulation, below, of the buck0 design does show a high takeoff angle compared with a regular J-Pole and a double 1/2 wave collinear J-Pole often called the Super J-Pole.

Regular and Collinear 1/2 and 5/8 wave antenna patterns.

Freespace EZNEC simulations are often practical, but what we care most about is real-world, just above the Earth, simulations. Below are the same three antennas with their bases about 360 inches above real ground in EZNEC…

Three different J-Poles over real Earth

This is more like it. Note the collinear 5/8 wave J-Pole does, indeed, perform about as well as a regular J-Pole in these circumstances at this particular azimuth. The half-wave collinear J-Pole beats out both antennas by about 2 dB. Here is a closeup of the lobes on the right…

Close up of EZNEC J-Pole Lobes

The buck0 5/8ths wave collinear J-Pole does perform. However, if I take the same #14 wire, use the same cool construction techniques, but make a traditional 1/2 wave collinear J-Pole with the feed-stub, a half-wave section, a quarter wave stub topped off with a final half-wave section, the antenna is a good 2 dB stronger than the double 5/8 j-pole from buck0 in over-Earth simulations at about 3 degree elevations in all directions.

Plus if you build a regular J-Pole with #14 wire you will do about as well as the more complex buck0 design.

Less wire… simpler feed… more gain… who knew.

At least the Collinear 5/8 Wave J-Pole works, but it seems clear with the admittedly simple EZNEC simulations above, your wire investment is better spent on the simple traditional 2m meter J-Pole or the Collinear 1/2 Wave (Super) J-Pole.

In particular one member has a magnificent full wave 160 meter loop up around 50 feet or so. He is contemplating using it for NVIS on 80 meters. He desires to lower it to about 15 feet to improve the NVIS characteristics.

It is true lowering a dipole will focus more energy straight up while reducing the energy towards the horizon. This is a tried and true technique on 80 and sometimes 40 meter NVIS and offers a potential added benefit of less sensitivity to far away thunderstorm noise. This is a method of diminishing returns; Lowering the antenna favors the sky more, but the overall gain is reduced. In other words, less signal is focused in a better NVIS favoring pattern.

Full wave loops are quite different as this EZNEC simulation suggests. Here is a simple four sided loop with 128 foot sides and fed near one corner – just like my friend’s 160 meter loop.

It is possible almost any antenna sends a little energy towards the sky for NVIS communications, but to fully take advantage of this capability, your antenna design should flood the sky with energy including straight up. This will ensure all possible angles of refraction/reflection are covered.

It seems clear from this very basic, but perfectly reasonable, EZNEC simulation a full wave 160 meter loop running in the 80 meter band is a good antenna for DX work, but leaves much to be desired for NVIS even if you lower it towards the ground like you do with a dipole. At 40 meters NVIS performance is even worse, but WOW the DX capabilities are nice even while the azimuth pattern is a four lobed cloverleaf restricting this nice low-angle gain to four general directions.

The proof of a 160 meter full wave loop antenna’s DX performance is highlighted by my friend’s achievement with his; He just finished 80 meter WAS… Phone… QRP… using, in part, this antenna. Wow.

…But I want NVIS
The practical solution is to keep your 160 meter antenna where it is and add a new simple 80 meter dipole 50 feet or less in height. This pair will team up nicely to get you want you need for 80 meter NVIS in addition to DX capabilities. Keep the 80 meter dipole well away from the 160 meter loop.

The sister web site to Ham Help Desk published several simulations of dipole discussing 40 meters and NVIS at…

Dipoles that are not too high are a quick answer for NVIS.

Other Techniques
Quadrature feeding two orthogonal dipoles, as discussed elsewhere on Ham Help Desk, yields circular and selectable polarization. This technique leverages what the ionosphere sounding folks use to probe the ionosphere at HF frequencies. This is what I am trying this year for the Virginia QSO Party. We will see how well it works.

Conclusion:
Big Full Wave Loops provide good NVIS at their native full wave frequency, but become more like DX antennas at higher frequencies. Loop antennas provide impressive performance at higher frequencies and are, thus, a great no fuss and simple antenna. However, other than the base full wave frequency, this antenna is less than ideal for NVIS above its base full wave frequency.

The above EZNEC plots detail the difference in gain you can expect with the loop antenna at different heights. For loops it seems higher is better. Other expensive improvements include laying a network of ground wires in a crisscross pattern underneath the loop. The simulations for this are not shown, but do reveal a real benefit in the total energy performance. I don’t have an unlimited supply of wire… do you? We will try to stick with the more practical antennas here at Ham Help Desk.

If 80 meters NVIS is your goal, consider a dipole or a full wave 80 meter loop rather than a 160 meter loop.

Both antenna types approach the vertical HF antenna problem with unique solutions.

The 43 foot antenna never changes height. Its height is such it never places the high impedance part of the antenna at the feed point at any desired operating band to give a tuner a chance to turn this wild impedance to 50 ohm resistive.

The BigIR literally adjusts height to make itself just the right length to resonate and bring the feed point close to 50 ohm resistive.

These are two interesting and opposite solutions.

Let’s look at the plots for 10, 15, 20, 40 and 80 meters again…

BigIR vs 43 Foot at 10 meters

- – - – - – - -

BigIR vs 43 Foot at 15 meters

- – - – - – - -

BigIR vs 43 Foot at 20 meters

- – - – - – - -

BigIR vs 43 Foot at 40 meters

- – - – - – - -

BigIR vs 43 Foot at 80 meters

BigIR points include:

• Beats the 43 foot handily at 10 meters
• The 1/4 and 3/4 modes for 10 and 15 meters offers a great choice in antenna pattern
• No antenna matcher required since the antenna length does the tuning for you
• Antenna SWR under 2:1 a completely reasonable expectation
• SteppIR’s clever variable length antenna and optional 80 meter coil have moving parts resulting in complexity
• BigIR needs 4 (or 8 with 80 meter coil) control wires to operate antenna from shack
• For what you get, the antenna cost is a great value, but is, indeed, not cheap

43 Foot Antenna points include:

• Provides a significant benefit for 20 meter DX with good gain and potentially low take off angle
• Requires some kind of antenna matcher for every band except, perhaps, 60 meters, at antenna feed point or in the shack
• Balun helpful to ensure currents are fully driven to antenna if not using matcher at the antenna base
• Arguably much simpler antenna system with no moving parts
• If matcher located at antenna base, additional wiring required

…and…

• Neither antenna differs much at 40 and 80 meters
• The 43 Foot antenna may provide some use at 160 meters – better than nothing I guess
• The 43 Foot antenna system between 1/3 to 1/2 the cost of the BigIR system not including the required antenna matcher for the 43 foot system

Which one to pick? Well, for me the answer is not obvious. I like antennas that present low SWRs to the feedline. I like simple antenna systems. I also like 20 meters a lot. I have no problem with the cost of the BigIR.

One obvious answer is to get one of each and switch between the two. Well, I do have the room and do have the switch. However, the whole point of the Shootout is to decide the most effective antenna if you could only have one.

With the upcoming sunspots the 10 and 15 meter bands look very attractive and a good ground mounted vertical may be just the thing. However, I have got to wonder if a modestly high 10 meter dipole won’t work better than the ground mount.

I am inclined to take advantage of the DX Engineering Zero Five price war and just get the 43 Foot antenna for now since it is a plug and play system to replace my current 16 foot vertical (which works great on 20).

My preparations focus mostly on the Virginia QSO Party where NVIS 40 and 80 meter antennas along with a decent 20 meter DX antenna are a great combination.

Whatever choice you make it is nice to know great products like the BigIR and the 43 Foot offerings are available. Just remember to not cheat yourself concerning a good ground system; Both antenna systems are incomplete without it. You need lots of radials. Read the ARRL Antenna book to nail down the reasons why.

A good vertical antenna is a sensible first antenna and a great addition to your dipole. Either choice will offer the possibility of lower takeoff angle to improve your chances at DX contacts. These two choices deserve a good hard look for your first or next vertical.

The 43 foot antenna uses an antenna matcher (tuner) somewhere in the transmission line to offset the non-resonant impedance; This is the case for all bands except, possibly, the 60 meter band where 43 feet is close to a quarter wave.

The BigIR max height is about 32 feet or about an 1/8 wave antenna. The BigIR continues to not need an antenna matcher by adding an inductance in series with the 32 foot radiator. This inductance brings the antenna system into resonance with a resulting impedance of about 13 ohms. A 4:1 balun wound on an internal toroid transforms this to about 50 ohms… a slick system.

Here are the two antennas with radials appropriate to 80 meters…

The 43 foot and BigIR antennas in EZNEC

…and the plots…

43 Foot and BigIR Compared at 80 meters

Very very close…

Points include:

• Both antenna exhibit 0 dBi gain peaking around 25 degrees
• Like with 40 meters, the 43 foot antenna puts just a little more higher current conductor higher in the air, but just a little
• The SWR for the BigIR calculates fine for this, but I have found EZNEC a bit difficult to predict SWR with real-world lengths. The folks at SteppIR suggests the SWR will be under 2:1 for the 80 and 75 meter bands when using their 80m option coil
• I could not simulate any respectable SWR with EZNEC for anything between 3.5 and 4.0 MHz – I suspect your results may be better since folks seem to have reasonable results

I would call these results a wash. Both antennas work on 80 even though both are short for this band. It might seem surprising they are so similar despite the height difference. However, this pattern similarity reveals not all of an antenna’s length is actually used for radiating effectively. Indeed, the high current portion of the antenna does much of the work and in this case the lower portion of the antenna is this higher current area.

Here are the two antennas with the current magnitudes at 7.15 MHz.

The two antennas energized with 7.15 MHz.

Once again, the 1/4 wave antenna’s currents are nil at the top and maximum at the bottom. Assuming you have a good radial system on the ground with low ground resistance this should be near the ideal of 36 ohms impedance. This results in a SWR of about 1.4 or so. The fact the BigIR’s 32 foot height won’t simulate a low SWR is probably the result of simulation artifacts. Either way this is good demonstration where the ideal SWR of 1:1, where the feed point impedance is 50 ohms and a good match for the coax, is not the ideal since this means you have 36 ohms antenna reactance (turns your RF into signal) + 14 ohms ground resistance (turns your RF into heat). That’s another story though.

Here is the plot…

43 Foot vs. BigIR Vertical at 7 MHz

Hmmm, not that different… not that different at all. Points include:

• Both antennas show their best lobe of energy at about 27 degrees elevation at -0.5 dBi gain
• The 43 foot has just a little more higher current radiating portions of the antenna a little higher than the BigIR
• The SWR (at least for the 36 simulation model) is nice and low
• The SWR for the 43 foot is about 5:1 for 50 ohm feed and a respectable 3:1 using the 4:1 transformer

Neither is a clear winner. The good news is neither is a clear loser. They both do the job of getting radiating metal up in the air to make contacts.

The 43 foot antenna provides the potential for better efficiency since its impedance is much higher than the ground losses induced by the radial system. This suggests you might be able to get away with a worse radial system with less efficiency penalty… I still would put a lot of radials in since it is so easy to do.

Onward to 80 meters next…

As always, each EZNEC simulation is based on a model from the excellent collection of NEC files available from the late Cebik.

Here are the two antennas with the current magnitudes at 14.1 MHz.

The two antennas energized with 14.1 MHz

As usual, the 1/4 wave antenna’s currents are nil at the top and maximum at the bottom. Assuming you have a good radial system on the ground with low ground resistance this should be near the ideal of 36 ohms impedance. This results in a SWR of about 1.4 or so. This is good demonstration where the ideal SWR of 1:1, where the feed point impedance is 50 ohms and a good match for the coax, is not the ideal since this means you have 36 ohms antenna reactance (turns your RF into signal) + 14 ohms ground resistance (turns your RF into heat). That’s another story though.

Here is the plot…

43 Foot vs. BigIR Vertical at 14 MHz

Well well, the 43 foot has some clear benefit here. It potentially has a lower take off angle and a bit more gain than the 1/4 wave. It is not staggeringly better, but if you are trying to get every dB you can, the 43 foot wins. Points include:

• The 43 foot vertical has its peak lobe at a nice low angle of 16 degrees with a gain of about 1.3 dBi
• The 43 foot has a full half-wave radiating section well above the radiating portion of the 1/4 wave which may help your signal clear local obstacles
• The 1/4 wave BigIR has its peak lobe at 27 degrees with -0.3 dBi.
• The SWR for the BigIR is around 1.5… perfect
• The SWR for the 43 foot was far more than 10:1 with a 50 ohm coax feed. If you have a 1:4 balun the SWR gets tamed down to around 7:1. Obviously a matcher is needed and contributes its own losses

Who wins? Well I don’t know. Analysis is showing clear benefits, but nothing that would move the S-Meter more than a couple of S-Units.

The fact the BigIR is tuned by adjusting its height makes it possible to reach the theoretical 36 ohms. This puts significant requirements on your radial system if you are to have good antenna efficiency.

The very fact the 43 foot antenna is being fed at a higher impedance point suggests the radial system’s impedance need not be as low to maintain good efficiency. Then, however, there is the need for the tuner somewhere with potential added losses.

I am using the equivalent of the BigIR with my 16.6 foot copper pipe monopole antenna in my backyard over 28 radials each 33 feet in length. It works on 20 meters, but I am not busting pileups with 100 watts. Would the 43 foot approach give me an edge with everything else being the same?

Stay tuned for more band analysis.

All three antennas, the 43 foot and the BigIR in 3/4 and 1/4 wave mode and their antenna currents are shown below.

All three antennas running at 21 MHz

The current profiles for the 3/4 and 1/4 mode are just like any other antenna the same electrical length. The 43 foot antenna constrains the electrical length to around 7/8 wavelength.

Here are the three patterns superimposed…

Elevation Gain Plots of 43' and SteppIR BigIR 21.2 MHz

Here we see:

• The 43 foot vertical has its peak lobe at 37 degrees with gain of 4 dBi
• The 3/4 wavelength mode of the BigIR has its peak lobe at 47 degrees with a gain of 3.8 dBi
• The 1/4 wavelength mode of the BigIR has its peak lobe at 27 degrees at 0 dBi gain
• The SWR for the BigIR is nice and low for both the 1/4 and 3/4 mode. It was slightly better in the 3/4 mode.
• The SWR for the 43 foot was off the charts

The 43 foot vertical definitely requires a tuner. Both DX Engineering and Zero Five suggest if you are going to use the tuner in your shack then place a 4:1 transformer at the antenna feed. This converts the 50 ohm coax impedance to 200 ohms. Indeed, when EZNEC is used to check SWR at 200 ohms, it is far lower, but still about 5:1.

At 15 degrees or so elevation all three antennas show similar energy with the BigIR showing an edge in both the 1/4 and 3/4 wave modes. At higher elevations the 43 foot begins to show an advantage.

It is hard to declare a winner with this data. We will need to analyze more bands. Stay tuned to the RSS feed.

However, there seems to be much hype about j-poles that make some folks think they have some kind of magical antenna properties. Indeed many folks report staggering improvements over their previous antennas. Is all the hype warranted?

Well, simulation is not a perfect endeavor, but can certainly help analyze simple antennas at a good enough accuracy to make comparisons possible and reasonable. Enter the contenders…

2 Meter Monopole vs J-Pole Antenna

In the left side of the ring we have the classic 1/4 wave monopole antenna with four drooping radials. On the right we have at a full 3/4 total wave in height the j-pole antenna.

These two antenna models are based on Cebik’s antenna collection available from his web site. If you would like to simulate these and hundreds more antenna models, seriously consider purchasing his collection.

Monopole compared to j-pole with feed point at 30 feet height.

The plot above shows the monopole as the primary trace in red compared with a j-pole in blue. Both have their feed points up 30 feet. The j-pole and the monopole have, for all practical purposes, identical gain in the primary low-angle lobe just above the horizon. Hmm, where is the benefit?

Monopole and J-pole with feed point 15 feet above ground.

The overall gain of both antennas is lower and the j-pole shows a slight edge of about .5 dB. This is still hardly worth much.

Monopole and J-Pole at six feet above ground.

Now we are beginning to see more difference between the monopole and the j-pole although both exhibit less gain than either at higher installations. Also, the primary lobe angle is higher above the horizon.

J-Pole EZNEC Simulations at 6, 15 and 30 feet above ground.

This plot above compares the J-pole at 6, 15 and 30 feet above ground to demonstrate the key benefit of getting your antenna, any antenna, as high as possible. You might be wondering why so much gain occurs beyond what theory tells you. One difference between theory and reality is theoretical antennas are frequently simulated in free space without the interaction from the ground. The ground causes absorption, reflections and other reactions that sometimes help and sometimes hurt our desired signal characteristics.

This simulation suggests the J-Pole offers some benefits to the operator, but not the fabulous and amazing results some claim to exist. The question is, then, why do so many folks get good results. Well, let’s examine some possibilities…

• Many new hams try a J-Pole (sometimes a ladder line variety) to see if it will be better than the rubber ducky antenna on their HT. By simple virtue of the J-Pole being almost certainly in a much better antenna location, there is no doubt the operator sees a vastly superior signal over the HT antenna.
• J-Poles are taller. This may seem silly, but getting that half-wave portion of the antenna well above the feed point of a comparison monopole results in a significant height improvement. This difference is more pronounced at low heights and may be why the simulation shows the J-Pole beating the monopole more so at six feet.

The diagram below show how each antenna placed at the common feed point height. The height advantage of the J-Pole is clear.

J-Pole and Monopole EZNEC Currents

The mystic of J-Pole antennas may cause some disappointment if folks are expecting more gain than a J-Pole can deliver. Don’t listen to the fabulous claims. If you desire to try a J-Pole just go ahead and do it. I did and I like mine just fine. Here are some advantages to a J-Pole…

• Some, but not staggering, gain improvements at lower elevations
• Slender design with little width
• Simple sturdy construction makes for a hardy antenna
• Entire antenna is at same dc potential allowing a grounded mount to dissipate static charge – however, the mast will become part of the antenna if you don’t choke the RF currents
• A truly balanced-feed half-wave antenna that requires no ground for use – compare this with transformer based half-wave antennas that MUST be coupled to a good ground for the coax-side transformer currents to flow (lots of people make the wrong assumption half-wave mobile antennas do not need ground)

J-Poles, whether copper cactus plumbing specials or ladder line types stuffed into PVC, work just fine, but don’t offer magical capabilities. Try one.

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.