However, there appears to be some kind of mystical attraction to the 5/8 wave radiator. Several of the J-Pole designs attempt to make the radiator 5/8 wave in length and adjust the phasing stub to make for a good match.

Let’s compare the two approaches using the models available from the late Larry Cebik’s NEC collection. Here are the contenders each using 3/8 inch diameter copper pipe…

1/2 Wave (left) vs. 5/8 Wave J-Pole

The current magnitudes resulting from the simulation are shown to reveal just how current flows in the conductors and, just as important, their polarity.

J-Pole fanciers already understand the 1/4 wave stub in the bottom part of the antenna, the J, have roughly identical and opposite currents which tend to cancel any radiation effects. This is very similar to ladder line when and if the currents are equal and opposite. Of course, where the 1/4 wave stub meets the bottom of the 1/2 wave radiating element current is not zero or no power would travel up to the radiator. This results in a slight imbalance in two currents.

The plot below shows the azimuth plot of the signals from both antennas. The 1/2 wave plot is at about 2.8 degrees above the horizon while the 5/8 wave peaks around 2.6 degrees. Each antenna is simulated with their base 360 inches over real ground.

1/2 vs. 5/8 Wave J-Pole Azimuth Plot

Both antennas exhibit asymmetry due to their 1/4 wave phasing stub small imbalance. The 1/2 wave J-Pole beats the 5/8 wave J-Pole by about 2 dB.

Here is the elevation plot of both antennas along the worst case azimuth bearing…

1/2 vs. 5/8 Wave J-Pole Elevation Plot

The asymmetry of a J-Pole antenna really comes to light here with a clear bias towards one side of the antenna. Note the 5/8 wave J-Pole has more energy at higher elevations at a cost of energy on the horizon where we want it.

So what are we to think about the extra copper and less balanced approach offered by the 5/8ths Wave J-Pole antenna?

My conclusion is you are better off sticking with tradition and build the 1/2 Wave J-Pole antenna.

A reasonable question is why isn’t 5/8 wave better. 5/8 wave is about the limit a vertical radiator can be to peak up gain towards the horizon. However, it assumes you have a very robust ground system to work against. A J-Pole has no such ground plane.

Another problem comes from the fact the 5/8 wave j-pole has that unbalanced current in the J part of the antenna. Thus the length of the antenna, electrically, is really something other than 5/8 of a wavelength. Such is not the case with a 5/8 whip over a good ground system.

5/8 Wave antennas have their place, but the term is used far too loosly in amateur radio circles. The J-Pole is one good example where deviating from tradition yields a functional antenna, but one with less performance than the simpler of the two antennas.

If you are considering building a simple J-Pole great! Build a 1/2 Wave J-Pole and don’t forget the balun.

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.

Unfortunately, one web site promoting a 5/4 wave antenna solution failed to realize you can’t make an antenna longer without eventually hitting a limit.

During commute time repeater discussions my friend was contemplating the use of a 5/4 wavelength vertical for his VHF antenna. He mentioned a web site with the construction details for just such an antenna which results in a nice simple no fuss vertical antenna housed in a PVC enclosure. Great, I thought, but I had some concerns over this whole 5/4 wavelength thing. I told my friend I would work up a simulation to see how good this antenna is. The first step was to find the web site containing the construction details for a 5/4 wave VHF antenna. This was easy resulting in this web site…

The author provides superb details on how to construct the 5/4 wavelength VHF antenna. He wisely predicted the installation into PVC would change the speed of light of conductors within. He revealed the need for a matching network. Good so far. In fact, I bet this antenna design provides a good match to 50 ohm coaxial cable, is of sound construction and will last many years in the elements.

However, that’s only part of the story isn’t it. How will the antenna actually perform.

EZNEC to the rescue…

While it is time consuming to simulate all the wire size and dielectric constant details the candidate 5/4 wave antenna offers, we can make the following assumptions and model accordingly…

• Since there is a parallel line component about 1/4 wavelength long, this is really an end fed full wavelength antenna with the extra 1/4 wave portion acting like an impedance transformer just like a J-Pole
• The existing models of J-Pole antennas from Cebik’s excellent NEC antenna simulation collection provide just what we need to start analyzing the full-wave antenna
• The 5/4 wave “tall” antenna will be compared directly to the 3/4 wave “tall” J-Pole

Both antennas are modeled with 18 AWG wire, used by the web site author for most of the vertical element, with the horizontal portion 300 inches over EZNEC’s “Real/High Accuracy” ground. Here they are with their RF currents shown…

Half vs. Full Wave Antennas

Those in the know will already spot trouble with the full wave radiating element. Those RF currents do not result in more RF radiation in the horizontal plane, but rather help to cancel it. For those of you experimenting with EZNEC be sure “Current Phase” is selected in the View Antenna options so you will see the vector, not just the magnitude, of the currents on the antenna view. You also need to ensure all your wires go in the same direction with end 2 connecting to end 1 of the next wire or the current phase might show incorrect vectors; The RF simulation plots work perfectly with wire direction either way, however.

Here is the full wave plot in red compared with a simple half wave J-pole in blue…

Elevation Plots of Half vs. Full Wave Vertical Antennas

Recall both antennas are simulated with the base 300 inches above ground with the following discoveries:

• The full-wave vertical is at least 7dB worse than the regular J-Pole at 4 degrees elevation – important for base to mobile and most any VHF communications
• The full-wave vertical shows negative 1.67 dBi gain at the terrain hugging low angles
• The full-wave does provide move energy at high angles which might be of benefit for base to air communications

I ran SWR calculations for both antennas and they both offer an excellent match to 50 ohm cable throughout the 2 meter band. For completeness here they are…

End Fed Half Wave (J-Pole) SWR

End Fed Full-Wave SWR (with J-Pole Feed)

What are we to draw from this?

First, great SWR does not a good antenna make.

Second, the full wave antenna does not, by itself, provide any benefit for terrestrial radio use and is, in fact, detrimental.

One can ask, though, how is it taller antenna designs provide better radiation towards the horizon.

The answer is based on the idea of making the RF current peaks in the antenna be in the same phase so the energy, towards the horizon, adds rather than subtracts. Many methods exist to achieve this, but one popular technique is to add a half-wave delay between the two half-wave antenna portions. By doing this we cause the current in the top antenna to be a full 360 degree delayed from the current in the bottom and, thus in phase. This technique results in a type of antenna generally called “Collinear.” The figure below illustrates how this is achieved in the popular Double J-Pole antenna…

Full-Wave J-Pole with Hairpin to make Collinear

Plenty of web sites exist to show how to build a Double J-Pole antenna so we won’t go into that here.

The UHF antenna on your vehicle may well have two or three antenna sections arranged as a collinear antenna with half-wave delay coils between each section to keep each radiating in phase. If we look at the evolution of the vertical antenna…

Evolution of Vertical Antenna

…we see 5/8 wave antennas tend to be the upper limit of length before phasing techniques need to be applied if we are to keep a good signal towards the horizon. Collinear antennas are a tried and true approach for antennas longer than 5/8 wave. Whether a hairpin or helical resonator is used to phase the 1/2 wave antenna “pieces,” improved performance awaits the antenna builder. As we any good thing there are diminishing returns by adding more co-phased antenna pieces.

The 5/4 wave antenna discussed is really a full-wave antenna with a 1/4 wave feed. The lack of an additional half-wave delay element between the two high current portions of the antenna suggest the author has missed an important detail in antenna design which will render the antenna far less useful than anticipated.

It is likely the author confuses his desire for a single wire antenna with dipoles of similar length – the extended double Zepp type is an example. The difference between an end fed piece of wire and a center fed dipole is, again, the current phases. A center fed dipole pushes current in one wire while pulling on the other thereby ensuring each dipole leg has current in phase – assuming the dipole legs diverge from the feed-point of course. This cannot happen in an end fed single wire one wavelength or 5/4 wavelength long without some means to delay the half-wave portions by 180 degrees.

However, the author’s noble attempt at antenna design and excellent construction techniques remind us there are other ways to apply his ideas to realize the suspected intent; A desire for a good sturdy Collinear antenna.

A final note worth considering is this… Can EZNEC or any antenna simulation program provide good enough results to use for antenna comparisons? Of course, but there are limits. If you are trying to see if one antenna is a dB or so better or worse than another you do need to be careful with the assumptions you put into your simulation. However, comparing a half-wave antenna against a full-wave antenna, both end fed with a 1/4 wave section, is well outside almost any margin of error so you can expect the full-wave antenna antenna to be far worse than the half-wave for horizon coverage based on the simulations above.

“With no real models for comparison, it is difficult to compare patterns for each antenna. I would suspect that the J-Pole would not have an omni-directional pattern and would therefore produce a lobe or lobes giving gain in some directions”

Really?

Larry Cebik’s antenna model collection contains hundreds of antennas to examine with NEC or EZNEC and the J-Pole is no exception. However, I did not find a coaxial antenna in his models. So I examined the original patent for the Coaxial Dipole antenna and found it was originally composed of several elements running parallel to the coax to provide the bottom half of the dipole. Great. The models for the J-Pole, the coaxial dipole and a reference typical monopole with 45 degree radials are shown below…

A J Pole, Monopole and Coaxial Dipole modeled in EZNEC

All three examples are simulated with their feed points at 300 inches above ground. The J-Pole enjoys a height advantage for obvious reasons. This advantage become more pronounced at lower elevations since the J-Pole’s height delta is a larger percentage of height above ground the lower the overall height is.

Height increases gain for all three antennas as the ground reflection begins to focus the horizon bound energy. No real surprise there. It is the relative gain patterns we really care about here. Here it is for Azimuth at an elevation about 3.5 degrees…

Azimuth pattern for Jpole, Monopole and Coaxial Dipole

Indeed, you can see the J-Pole’s lack of perfect symmetry results in a slight benefit in certain directions as correctly assumed by the ARES article author. However, the difference is not very significant at less than 3 dB. Also, there are no lobes of gain or loss, in azimuth, like the author theorizes. Lobes do exist for elevation for all three antennas.

Here is a comparison of elevation…

J-Pole, Monopole and Coaxial Dipole EZNEC Elevation

The J-Pole enjoys the most gain at around 6 dBi with the other two antennas pretty close to this value. Again, all three antenna’s gain is very dependent on the height above ground. Thus, the J-Pole always has a slight advantage. Otherwise, the J-Pole is just a half-wave radiator like the coaxial dipole with a slight height advantage.

What are we to make of all this? Well, don’t listen to anyone who tells you one antenna is dramatically superior in performance to another. In the end, they all, more of less, behave like a half-wave radiator and all are a little better than a 1/4 wave monopole over horizontal radials.

The Monopole is the one that bests matches to 50 ohm coax thanks to the angled radials. The coaxial dipole simulates to around 80 ohms impedance which is close to the 72 ohm half-wave value. The J-Pole feed is, indeed, a bit complicated, but matches 50 ohms very well.

So put performance issues aside and concentrate only on the mechanical issues when selecting your next VHF antenna.

Also, you now know better if someone tells you there are no real models for comparison. Simulation has its limits, but is an excellent first step. You can rest assured an antenna invented in the 1930s has been modeled at least once.

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.

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…

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.