Wednesday, January 28, 2015

Exploring Verticals with a 4-radial Ground Plane Model

Vertical antennas is a subject that currently interests me since I feel the pain of a poorly-performing antenna for 80 meters. It is noteworthy now that I'm running 100 watts in the DX pile-ups. For example, I quickly cut through the pile-ups to work C5X on 40 meters and above yet ran head first into a brick wall on 80. It isn't all bad since I have had a few notable DX successes on 80 with the loaded half sloper, and I did even better years ago with a full-sized half sloper. They will do if nothing better is available.

The EZNEC (NEC2 engine) modelled loss of my present antenna over medium ground is about -6 db. This understates the reality since the ground in my yard is worse than that, and there are many housing-related long conductors in the antenna's near field. I am, in effect, dialling down my recently-acquired 100 watt rig to QRP. What it does when I operate with my KX3 is dreadful to contemplate. Yet that's how I currently operate on 80: very, very poorly. I had similarly poor results with my experimental and vertically-polarized loaded sloper on 40.

Verticals are nice but radials and interactions with obstructions are a problem in suburbia. I have therefore avoided them over the years even though I know how well than can perform on the low bands. Software modelling of verticals is tricky due to their strong interaction with ground, regardless of the number of radials or high-conductance ground screen. Horizontally-polarized antenna are more predictable.

Motivation: use my tower as a ground-mounted vertical

To address the problem it is helpful to step back and consider what radials do and don't do in various antennas. If I want to load my tower as a monopole on 80 it would be helpful to choose the length and number of radials that minimize the loss without creating a backyard tangle of wires. However, first let me place this in context by presenting my thoughts on how I might utilize my tower on 80.

The first thing is to determine the electrical length of the tower. It is loaded by a tri-band yagi 15 meters above ground, which is the very top of the structure. ON4UN presented a simple formula for estimating this important datum in his book Low-band DXing. (Note: I am using the 1987 version which may have since updated this item.)

Using that formula the electrical length of my tower plus tri-band yagi is 100° at 3.6 MHz, or about 10% longer than λ/4. I then added 4 radials to my EZNEC model of the tower and yagi. ON4UN's formula was surprisingly accurate, with the antenna resonating at 3.3 MHz. Since the feed point resistance was a good match to 50 Ω I only needed to add a series capacitor of 900 pf to get a good match that can cover the entire band (500 kHz).

That sounds good, if it were only that simple. First, this feed requires that the tower be electrically isolated from ground so that the radials only need connect to the coax -- use the braid for the radial connection so that the coax outer surface can serve as a radial, if it isn't buried, and it's choked before entering the house.

While my tower is sitting on a wood platform and the guys are isolated with insulators there will still be conduction from tower to ground. The wood base is not a high-quality dielectric, especially when wet, and it has 1 m² contact area with the soil. Last, the half sloper must be removed, strapped to the tower or isolated or it becomes an active part of the vertical, and not in a good way. All the other coax and rotator cable will also affect performance unless radically reconfigured. Thus a more reliable approach to feeding the tower is to connect the radials to the tower and build an omega match. It is then also easier to adjust the match.

The modelled ground loss is -5 db and the radiation at 10° elevation is -2 dbi. The loss is 1 db better and the low angle gain is 3.5 db better than the loaded half sloper. Thus 1 db of increased low angle gain comes from the lower loss and the other 2.5 db from excising the excess high angle radiation of the half sloper.

Both models push NEC2 far enough that the reported ground losses are inaccurate. When adjusted in the manner recommended by W7EL the relative difference in loss (and gain) is lower by ~0.7 db. So the adjusted losses are comparable, though the vertical still excels at low elevation angles. However questions remain regarding loss in the model.

When modelled over poor ground (as in my case) the (adjusted) losses are -7.2 and -8 db for the half sloper and vertical, respectively. If this seems surprising note that the average current height is higher on the half sloper, and therefore is less negatively impacted by ground. You can easily add radials to the vertical for lower loss, but not for the half sloper.

The loss in both antennas perversely contributes to their excellent SWR since ground is a broadband resistor in series with the radiation resistance. I mentioned this very thing when I commented on the unexpectedly good match of the loaded half sloper, which the model did not fully anticipate. My especially poor ground (not medium) is likely to blame.

Despite the uncertainties this approach may be worth an experiment this winter, if I have the time. Direct A-B comparison with the half sloper is not possible due to the previously mentioned requirement of putting it out of the way. I recently found a large roll of 22 AWG insulated wire lurking deep in my junk box which can serve for radial experiments. After 20 years of inactivity I am frequently surprised at all the gems I am discovering I already own. I don't remember half the stuff I keep finding.

Basic model: 40 meters ground plane with 4 horizontal radials

Now that you see my motivation I will switch over to a simpler model to demonstrate a few attributes of verticals and how they affect performance. By performance I mean efficiency: getting as close to 0 db ground loss as possible. With 4 or more radials, a monopole height near to λ/4 and no obstacles in the near field the far field pattern will be omnidirectional with a single low-angle lobe. That is, the pattern is unaffected by antenna height, radial number and length, ground quality or match.

I am using a model for 40 meters since it is easier to visualize. Lots of hams use ground planes on 40, but on 80 almost all verticals are ground mounted with surface or buried radials: the mechanical requirements of a raised base on 80 are considerable. The 4-radial ground plane is perhaps the simplest of the breed since 4 is the minimum number of radials to achieve an omnidirectional azimuth pattern. It's a good place to start the exploration of radials and verticals.

A further reason is to enable a comparison to the extensive data in a 2-part QEX magazine article by N6LF: part 1; part 2. My simpler treatment of the subject is intended to narrowly focus on a few aspects of these antennas' relationship to ground, especially as it relates to my particular needs and interests.

Questions to be considered:
  • How does height of the antenna above ground affect radial behaviour?
  • How long should the radials be?
  • How much does the impedance change with radial configuration and height?
  • How much does the ground loss change with radial configuration and height?
A commonly-held tenet of radials is that when above ground (a ground plane vertical) they and the monopole should be λ/4 long. For a ground-mounted vertical the rule is that radial length is less critical and can be non-resonant, sometimes shorter and other times longer than λ/4, or even a mix of lengths. There is truth to these practices even if it is not immediately obvious why. This is where models come in handy.

In NEC2 (the engine use by EZNEC and EZNEC+) radials cannot be placed on or in the ground. That requires NEC4 (available with EZNEC Pro), which is expensive. However as W7EL recommends it is possible to model surface radials by lifting the antenna slightly above ground, by at least 0.001λ. In my models I make this distance 10 cm on 80 and 5 cm on 40, slightly above the minimum. This seems to work pretty well.

Free space

To start I will place the antenna in free space to discover its properties in the absence of ground effects. That will be our baseline for comparison. To be resonant at 7.1 MHz in free space the wires are zero loss 16 AWG bare wire, with each radial and the monopole 10.525 meters long. While not fully realistic it is a good place to start since we avoid several confounding variables. Feed point impedance is 22.2 Ω.

Notice anything odd about the free space elevation pattern at right? Despite its asymmetric structure the ground plane radiates equally above and below the plane of the radials. The radiation from the radials cancels so that there is no net horizontally-polarized radiation in the far field. All of the far-field pattern comes from the λ/4 monopole. At this point it should be clear that the radials are not behaving in the manner that many hams would guess or expect. Keep this in mind since we'll later see how this impacts performance.

Performance vs. height above ground

Now let's bring ground into the picture. I'll start by placing it 10 meters above medium ground and lower it down to ground from there, measuring change in resonance, feed resistance, loss and low-angle radiation. I did the plot in a manner that might look odd since I scaled some variables to improve presentation on a single chart.

At 10 meters height the resonant frequency is already shifting upward, until is dives sharply lower as the ground is approached. The feed resistance at resonance gradually increases as the antenna drops lower. Loss is surprisingly stable, remaining in a tight 1 db range.

The antenna's interaction with ground is interesting, and perhaps not what many would expect. An increasing proportion of the near field is penetrating the ground as the height is lowered. Go back and look at the free space elevation pattern as we review a few points.
  • The velocity factor of the radials declines as ground is approached, pulling resonance to a lower frequency. Each radial is like an insulated wire where the thick, lossy ground is the insulator. The ground parameters -- conductivity and dielectric constant -- determine the effect. Every part of the antenna, radials and monopole, has its own contribution to the near field, and it is strong within λ/4. Much of the energy associated with the radials and monopole is flowing in the ground, not on the conductors.
  • Feed point resistance steadily increases as ground is approached. This is likely due to the series resistance of the ground coming increasingly into play.
  • Ground loss is not much different over this range of heights. Indeed it only starts to substantially drop as the antenna is raised to unrealistic heights. The "ripple" is partly due to NEC2 inaccuracy at the lowest heights, though I did adjust the values using techniques suggested by W7EL. A confounding effect is from the monopole's ground interaction and affect on the far field pattern. I did not attempt to determine how much each factor contributes to the loss.
  • Low-angle radiation shows a remarkable change with height. Higher is better. I don't often see this discussed in other articles about this type of antenna..
7.1 MHz 4-radial ground plane at 0 and 10 meters height
A ground plane antenna that is well above ground level is notable as a good DX performer. Not only does it get above at least some obstructions (houses, etc.) it has good low-angle radiation. That performance does not come from lower ground loss (as should be clear from the chart above), but from the far field pattern change due to ground reflections.

Look again at the free space pattern above and then the adjacent elevation pattern. Like a horizontal antenna a vertical antenna benefits from being higher. This holds true whether it is a ground plane or a "no-radial" vertical dipole.

What radials do

Not all radials are alike. There was a time when I (like many) was confused by some verticals requiring different length radials than others. For some the radials must be λ/4, with a λ/4 vertical monopole. Other styles of vertical can have non-resonant radials that can be shorter or longer than λ/4, yet still with a λ/4 vertical monopole. What is going on here? Can both be right?

Let's hear it from W7EL, as stated in his EZNEC user manual:
The effect of radials and other buried ground systems is widely misunderstood. In a typical quarter wavelength high vertical antenna, the ground has two distinct and somewhat independent effects. One is that the current flowing into the base of the antenna is matched by an equal current flowing from the ground to the other feedline conductor. This current flows through the ground and incurs loss in the process. The primary purpose of a buried ground system is to reduce this loss by increasing the conductivity of the ground near the antenna. The effect of a poor ground system is to reduce the antenna efficiency. This reduces the strength of the radiated field, but doesn't change the antenna pattern.
The other purpose of ground (as he goes on to describe) is as a reflector to form the far-field pattern. Since that is not done with radials I will skip over that for now to briefly consider the near field, under and near the antenna.

Both the radials and the ground provide a return path to the feed point (generator). However for the ground to do so there must be a direct ground connection of some sort, such as a ground rod or metal stubs in concrete (Ufer ground). In effect the radials and ground act as a set of parallel conductors, where the radials are low resistance and the ground is high resistance. As more of the return path is via the radials the lower the ground loss in the near field. Longer radials can capture more of the near field at the cost of often undesired effects on loss and pattern, due to the radials becoming self resonant.

Pounding a ground rod into the ground does provide a return path in the absence of radials. However even with good quality (high conductivity) soil all you`re doing is building a high quality connector to a big resistor. Other than dipping a ground wire into salt water radials always provide the least lossy return path.

When the antenna base is above ground you should only use radials, and not make a direct ground connection. The wire from the antenna base to the ground connection has a radiation resistance and will degrade antenna behaviour.

Radial length sensitivity analysis

If you've ever researched or experimented with verticals you'll likely know that there is a great deal of flexibility in their permitted length. That is, the antenna doesn't change much until the radials are shortened or lengthened by more than you might expect. Let's look at this behaviour in the case of the model 4-radial ground plane for 40 meters with its equal length radials and monopole.

What I did was to vary the radial lengths by 2% and measure the change in resonant frequency, and I did so at base heights from 0 to 10 meters. Then I did the same for the monopole. The idea is to numerically discover the derivative (rate of change, from calculus) of frequency with respect to length, for this particular scenario, and thus tuning behaviour of radials and the monopole. The derivative will be different (not a constant) at other base values, though we don't need to deal with that right now.

I usually would present a chart at this point but that isn't necessary. The rates are constant (within modelling precision) within the chosen height range of 0 to 10 meters. For a 2% change in length the resonant frequency changes by 0.4% and 1.6% for the radial length and monopole length, respectively. If they had contributed equally both values would be ~1%.

This tells us that there is no need to fuss over the radial lengths, within reason. Conversely the monopole is more sensitive to length change than expected. Therefore a reasonable tuning procedure would be to cut the radials first and then adjust the monopole length to resonance. If you shorten the radials a lot you would compensate by lengthening the monopole ¼ as much. Just keep in mind that this only addresses resonance, since large changes in radial length impact ground loss (longer is usually better). But when approaching an electrical λ/2 (watch that ground dielectric constant) can cause significant misbehaviour. See the N6LF references given above.

That is for 4 radials, which is a reasonable number for a ground plane mounted above ground. Mounted on the ground and with more radials the situation is different. I won't get into that, or at least not in this article. My modelling experiments so far make me suspect that NEC2 is misreporting ground loss for large numbers of radials even though I have not (yet) found any obvious error in my approach. However I do feel safe in stating that for more radials their length can be shorter without significant additional loss, though probably not less than λ/8.

As one final exercise on this topic, let's assume the above rates of change are linear -- that isn't really true but is good enough for a first-order estimate. Then the 3% lowering of the resonant frequency at 0 meters height is equivalent to a velocity factor of 0.85; that is, radials lying on the ground. There are experimental results out there that measure self-resonance of surface radials in the 0.4λ to 0.45λ interval so this appears to be consistent. Another way of saying this is that λ/4 surface radials would have to be cut to a physical length of about ~0.2λ. Off the ground by more than ~0.1λ the velocity factor is close to 1, so the electrical and physical lengths are equal.


I earlier showed how the ground-mounted vertical can be directly fed by coax. The typical feed resistance at resonance is 30 to 35 Ω, or higher with ground loss added in, which is a good match to 50 Ω. On 80 meters you can have low SWR across most of the band, and certainly correctable with a typical transceiver ATU. The modelled 4-radial vertical made from my tower and yagi has a feed point resistance of 34 Ω.

If you are loading a tower plus yagi (as I would be) the direct feed method would most times require a series adjustable reactance (coil or capacitor) to bring resonance where you want it. For more flexibility an omega match is recommended. If the tower is grounded, or even if anchored in concrete (see Ufer ground) you should connect the radials to the tower and use an omega match.

When independently constructed and mounted above ground a ground plane antenna is easier to match. With the several radials sloping downward (and often doubling as guy wires) the feed point resistance can be very close to 50 Ω. This is useful to know. If nothing else, the common lore regarding feed point resistance of various vertical antenna styles is correct.

Conclusions and next steps

For a brief foray into the wide world of vertical antennas I am learning quite a lot. Although preliminary there are a few conclusions I would hazard to make. I also have some ideas on where I need to go from here.
  • Rather than run a large number of radials to reduce ground loss it can be easier to improve low-angle DX performance the same amount (1 to 3 db) by raising the vertical`s base. This can also reduce interference from and interaction with nearby conductive obstacles. The near field on the low band extends quite far.
  • An omega match, while not always required, is worth the trouble to ease adjustment of the vertical`s resonance and impedance. Turning a knob is easier than trimming 32 radials or moving a yagi up or down a tower!
  • On 40 meters you can probably get equal or better low-angle performance by using the monopole as a support for an inverted vee. Compare the gain charted above to other antennas for 40. Even so many do use verticals in 4-square 40 meter arrays to achieve 5 to 6 db of broadband gain. However on 80 and 160 it is usually easier to get good low-angle performance and array gain from λ/4 verticals than from a horizontally-polarized antenna. It`s often too difficult to get a horizontal antenna up high enough for it to be the superior choice.
What I can do next is uncertain. For the next several weeks I am too busy with other things to construct an experimental 80 meters vertical out of my tower and yagi. The colder than typical weather we`re experiencing this winter is also dampening my enthusiasm. Perhaps I`ll do it in the early spring. Unfortunately this means I`m stuck with a poor antenna for 80 in the coming contests.

Regardless of what I physically build, I do plan to explore software models of verticals using more radials of various lengths to gain additional insight into lowering ground loss and increasing low-angle performance. The literature is clear that more and shorter radials can work well. Shorter radials would be a great advantage in my yard which is 15 meters wide and where the tower is set back 15 meters from the house.

Wednesday, January 14, 2015

Whither QRP?

My very first transmitter in 1972 used an 807 final, managing perhaps 40 watts. That was as close to QRP I got since, like many, I believed that bigger was better. Provided my budget and living arrangements permitted it, every station change since then was a step upward. That is, until 1992 when I abandoned the hobby for other things.

When I returned to air in 2013 after 20 years on inactivity I decided to do so in the smallest way possible: low power and no outdoor antennas. Since my venerable FT-102 was not working I chose to purchase a KX3. QRP fit the bill at the time since I could play around and test my renewed interest in the hobby, and do so without any risk of EMI at home or in the neighbourhood. The first antenna was the aluminum eaves trough winding around the roof of my two-story house.

After a few months with the eaves trough antenna I went on to build better antennas and (necessarily) reintroduce neighbours to my old hobby. Despite subsequent antenna size increases I stuck with QRP because I came to enjoy the idea of doing big things with little power. That is, the challenge motivated me to stay active.

More importantly it kept amateur radio as a hobby, one where I was no longer obsessed with "bigger is better" and feeling obliged to do well at DX and contests. The pressure was off. The old imperatives don't take hold of my mind as they once did. If I up my power I don't think it'll corrupt my thinking. Thus I firmly set the acquisition of a new rig and more power in my 2015 plan.

I have accomplished quite a bit with QRP and a small antenna farm over the past nearly-two years. My updated DXCC totals as of early January are posted at right. Compare these with my results at the time I dismantled my station in preparation for the new tower and yagi.

My contest results have also been good, and can be found by a search at 3830. All my results are with QRP, 10 watts for daily operating and 5 watts in contests.

What's driving me away from QRP is the plateau I'm experiencing. I've reached the point of diminishing returns, especially in my primary interests of DXing and contesting. Even with the tri-band yagi my DXCC count only increased 20 entities over the past several months. I can eke out more with my current setup but I have to admit it is becoming fatiguing. My predicament has gotten worse with my foray onto 80 meters where working much within North America with QRP is difficult, let alone DX. A better antenna would help but I can't do much more with for low band antennas at this QTH.

With the inevitable decline of sunspots, increased geomagnetic activity and a renewed emphasis on low bands the limits of QRP are evident. Further, I don't believe that I have anything to prove by persisting with QRP. Consequently the following box has found a home in my shack this week.

This is the Yaesu FT-1000MP Mark V Field. According to the serial number it is 13 years old. It should be obvious that I purchased it used. It needs some cabling and modification to integrate well into my station and meet my operating needs. I have put it on the air for several QSOs and proved what a 10 db power boost can accomplish. I muscled through a 40 meters pile-up and worked a weak UA0 on 15 meters that I otherwise would not attempt with 10 watts.

Getting this rig is about more than power. The KX3, wonderful though it is, has its limits. Most of these are in the receiver. There is only so much performance you can get with direct conversion and DSP filtering. I plan to write a comparison of the KX3 as a base station and DX/contest rig versus the FT-1000MP in a future article, and why I selected this particular transceiver.

I can now also enjoy SSB, which is not often possible with QRP. In retrospect it's a shame I chopped off the Yaesu 8-pin connector from my Heil headset. I will have to make an adaptor so that I can use the 3.5 mm mic plug on the headset with both radios.

The KX3 is not going anywhere! I like it, so it stays. I will now have two rigs in my shack. This also does not mean that I am done with QRP. I remain uncertain whether it is a good idea to run 100 watts at all times. I lean towards staying with QRP for the remainder of this season's contests. I might use the KX3 in contests or the FT-1000MP with the power turned down to 5 watts.

Once I have the new rig sufficiently integrated with station hardware and software I intend to push my DX progress. I will not separately catalogue my DXCC count as QRP. Therefore the table above is my final tally for purely QRP DXCC. What I will do is stick with the count starting with my return to the hobby in 2013. This is more meaningful to me than sorting through mounds of records and QSL cards from the distant past. I enjoy DXing, not the collection of certificates. I have in fact never applied for the DXCC award.

While I proceed to enjoy the power boost I will wait and see if any of my neighbours notices.

Wednesday, January 7, 2015

Ice and the Geostrophic Wind

There are worse areas to experience freezing rain that where I live, though we do experience it several times every winter. Below Lake Ontario (New York) is the snow belt and above the lake, where I am, is an ice belt. As the weather systems proceed toward the east these seem to combine and deliver a double whammy of ice and snow to Quebec (VE2), New England (W1), the Maritimes (VE1, VE9, VY2) and Newfoundland (VO1). Hams along the eastern seaboard of North America know this all too well.

Ice loading is hard on antennas and their support structures. Ice not only adds substantial weight it also increases wind load. When the ice melts or fractures it can come off unevenly which can twist yagi elements and break wire and rope. Of course the weather conditions can make it hazardous to effect repairs, often for the remainder of the winter. Unfortunately this is prime contest and DX season. It is therefore important to build antennas and towers to survive winter.

All this came to mind when we were hit with consecutive snow and ice storms this past weekend. Happily it wasn't bad as these things go. Hardened as we are to the weather in this part of the world it was no more than a minor inconvenience.

In the photos above and below you can see some of the ice and its effects. The ice isn't thick, just a few millimeters. It is enough to make a ⅛" guy wire grow to a little over ¼". The same coating went on the wire antennas and yagi yet little adhered to the towers. The weight of the ice lowered the limbs of the large spruce tree to the ground. In bad storms they're completely flattened.

This is not enough ice to cause damage except in the most flimsy of antenna installations. The trees will rebound and the antennas will continue on as normal. The only problem was that the resonant frequency of the wire antennas dropped about 6%. Ice is a dielectric that lowers the velocity factor of the wire, increasing its effective length and so lowering the resonant frequency. The yagi experienced a smaller change. Rain's impact is different in that there is not enough water to appreciably lower the velocity factor but can cause end effects which similarly lower resonance. That is probably happening here as well since ice (fresh water plus impurities) coats the insulators.

Tower manufacturers should and mostly do specify load capacity under ice conditions. When the wind blows the ice-laden tower can carry less load. Since the tower must first be able to support itself at the rated wind speed, this means a lower capacity for antennas.

First, ice lowers wind load capacity by increasing the static load (dead weight). Bending stress increases due to the weight. That is, the tower will fail with less lateral load. Second, the ice increases the wind surface area of the tower itself, lowering the wind speed at which the tower itself will fail. This is why there is less capacity for the antenna load. Third, ice increases antenna weight and wind surface area.

Consider the following tables published by Trylon (a manufacturer whose towers are commonly used by amateurs in Canada and by some in the US) for their Titan series of self-supporting towers. The first is for wind alone, and the second is for a select example of severe icing.

Trylon provides a calculator so that you can determine tower capacity due to wind and antennas alone. The calculator does not take ice into account, which is a complicating factor not easily integrated into a general formula. That Trylon excludes ice as a factor in its calculator should not be taken as license to ignore it. They would rather you consult them or hire an engineer.

Too many hams in this climate who otherwise properly engineer their antenna systems for the maximum winds they should expect to experience (wind zones) fail to take ice into account. A typical reason is they don't expect severe wind and ice to occur at the same time, thinking that is too improbable an event. I, too, have been guilty of this oversight.

Unfortunately wind and ice are not statistically independent variables. The two are often causally connected. To understand this we must detour to review some meteorology. That should illuminate the danger of ignoring ice load.

In this part of the world the typical weather pattern is for a succession of high and low pressure systems (anti-cyclones and cyclones) travelling west to east. Air moves from high to low pressure areas, and circulating vertically from the warm low to the cold high. This is obviously a simplistic description but still useful. The coriolis effect mediates the air flow (wind) such that lows circulate counter-clockwise and highs circulate clockwise in the northern hemisphere. The 3-O's mnemonic aid: a low rotates counter-clockwise in the north.
Geostropic wind

Wind speed increases as the pressure gradient increases (isobars closer together) with low and high system intensities and proximity. Air spiral outward from the high and finally spirals inward to the low. Balanced in between, parallel to the isobars and approximately on a line connecting system centres lies the geostrophic wind. The diagram at right illustrates this, though you may find it helpful to mentally rotate it 90° clockwise so that north is at the top.

Under suitable conditions the approaching low draws a warm, moisture-laden wind from the southwest, which cools as it flows north and causes precipitation. In our scenario it begins as snow accompanied by high winds, becomes rain as the cyclone centre approaches, and a decrease in wind in the eye of the cyclone. If the warm air is pushed up over the cooler air what begins as rain at altitude freezes on contact with the ground, or antennas. That is a common way to get freezing rain occurs in this region.

As the low continues eastward the winds shift to the west then the northwest as the geostrophic wind asserts itself. This wind is colder, coming as it is from a high and from the northwest. The amount of ice and speed of the wind are related since both are related to system intensity.

Therein lies the danger: the worse the icing the worse the following cold geostrophic wind. Unless the systems are moving slowly the ice doesn't melt but is fixed in place by the cold. Now you should begin to see why Trylon's ice load chart above is so important.

While it is rare for extreme winds in these weather conditions it doesn't have to be. Look very closely at those reductions in capacity. Even as I type these words 3 days following the storm the ice is still encasing the antennas, the temperature is -20° C and the wind gusts are topping 60 kph. If the ice had been thicker the risk of tower failure would be a concern. This combination of weather events can and has brought down many towers over the years, both amateur and commercial.

I had a particularly bad case of ice loading on my tower and yagi stack back in the 1980s. I was lucky that most of the ice fractured and fell off before the wind arrived. It was a tense 24 hours.

There is a reason why Maritimers tend to shorter towers and smaller antennas. It gets expensive to replace them every few years. Of course living on the Atlantic shore you can do very well indeed with less antenna. Not so here.

Sunday, January 4, 2015

2015 - Challenges Ahead

2014 has now come and gone, so it's time to check back with my plan for the year to see how well I measured up. Then it's on to my amateur radio objectives for 2015.

One thing I've learned from decades in the business world is the value of stating objectives up front, making firm plans and then to measure performance against those plans. This isn't for everyone, nor should it be. For many this hobby is simply a casual pastime. Even then there is value to accepting some structure. If you can clearly express what you want to do you can articulate, and follow, the steps necessary to make those things happen. When done right it can lead to a satisfying result. Even for a hobby that's important.

2014 retrospective

My stated plan for 2014 was largely fulfilled. Not entirely of course, but enough to give myself an A or B+. Let's look at the key misses first: more power and 40 meters.

With the delay into early fall for getting the tri-band yagi raised I did not want the additional pressure from have to search for and purchase a new transceiver. Therefore I kept operating with QRP right through 2014. I was also more interested in testing my ability to score well in the fall contests with QRP than transitioning sooner to higher power.

My hopes for a gain antenna on 40 were dashed. Destructive interactions to the tri-band yagi pretty much ruled out a switchable wire yagi on the tower. With the yagi up only 15 meters there was no way to get sufficient separation from a 40 meters yagi and yet keep the wire yagi high enough to deliver better results than the inverted vee on 40. My attempt to create a sloper array just to Europe was shelved when my single sloper experiment didn't work out. I learned a lot but my station didn't end up any further ahead.
There were also areas where I exceeded my expectations. Those are also worth a look.

With the yagi in place and a poorly-performing 80 meters antenna, plus some great conditions, I was able to place high in the QRP global rankings in both the CW and SSB weekends of CQ WW. Although this remains to be confirmed after log checking I don't have to wait to declare success. The power and antennas delivered results. Any remaining problems would be in the operator, not the equipment.

Despite what I said above about my failure to build a better antenna for 40 I have come to believe the 40 meters inverted vee is doing better than expected. Although I cannot compare them directly, on the basis of results I now think it does better, broadside at least, in comparison to the delta loop that was taken down earlier in the year. It just goes to show how local ground and suburban clutter can negatively affect the DX performance of vertically-polarized antennas.

Since the yagi went up my DXCC total increased to 226, an increase of 20. Even on 80 I have managed to eke out 30 countries. My LOTW confirmations are now over 100 on 40, 20, 15 and 10 meters, and just shy of the mark on 17 meters. That's good for less than 2 years with QRP and modest antennas, antennas which up until 3 months ago were single element and no gain.

I do not have an antenna for 160 nor do I seriously plan one for this QTH. An antenna can surely be built but it would have to be a poor one. Nevertheless I decided to enter the ARRL 160 meters contest in early December for a laugh, just to see what I could do with 5 watts and no antenna. By "no antenna" I mean unscrewing the outer ring of the PL-259 of the 80 meters half sloper. It's an old trick that I've used before.

The surprise was making over 100 QSOs with this ridiculous setup. I could hear some DX, but though I worked none of it I did get as far as Oklahoma. Most QSOs were a struggle to complete, which is no surprise. Of course I was amply assisted by the big antennas and good ears of other operators. It was unexpected fun, and educational.

2015 plan and constraints

My plans for the VE3VN antenna farm in 2015 are more modest than they were for the previous year. Back then I was starting from very little so there was ample room for improvements. That is less so now, and I am running straight into several constraints on what I can or should do at this location.

First, the constraints:
  • Radials: These are not compatible with the use of my yard, nor is there really a lot of room on the east-west axis to run radials. Yet I need radials if I am to increase the efficiency of low-band antennas, and even venture down to 160 meters. My present 15 meter high tower models well on 80 and 160 as a vertical, but only with a good radial system.
  • Power: I can increase power to 100 watts but no further. I know from experience that going above this will lead to neighbourhood EMI problems on 20 and above. It could work if only used occasionally, such as to break a pile-up, but is out of the question for regular use and certainly not in a contest.
  • Noise: My immediate neighbourhood is full of noise sources. Most sound like LED light systems, but there are many more that are harder to identify. It isn't a solvable problem. Most hams face the same situation. Poor reception is acceptable for QRP since the noise mostly covers up the weak stations that would never hear me anyway. Increasing power and a large antenna investment would show a poor return. Overnight to early morning are best since that is when lights and appliances are mostly turned off. Evenings can be quite bad, especially in winter when the sun sets soon after 4 PM.
  • Tower: A permanent tower requires a concrete base. From my original site plan this could only go at site B or D due to the location of the septic system tile bed.  (Site C is where my tower and yagi are currently located, right on top of the tile bed.) Site D is preferred due to the municipal tower policy and setback requirements. Going above 15 meters height also requires "consultation" with all of my immediate neighbours for the same reason. That is more of an inconvenience than a significant problem. Even so a large tower may be a poor investment at this QTH due to my growing ambitions. Why spend all that money and still have physical limits on what I can get in the air, power limit and reception difficulties due to noise?
With the above limitations I can see myself doing the following in 2015:
  • 100 watt transceiver: I am already shopping, so it will happen. I am not only motivated by power but by the need for a better receiver. The Elecraft KX3 is a great little rig though one with serious receiver deficiencies in comparison to the best. I may detail my KX3 experience in a future article.
  • 80 meters: The ground in my yard is dreadful, far worse than the "medium" ground I typically use in my models. Although permanent radials are out of the question there is the possibility of a winter-only antenna using the 15 meters tower and yagi as a monopole on 80. Initial modelling shows promise. It is worth the experiment, once I dig up a large quantity of cheap radial wire.
  • 6 meters: This lowest VHF band used to be one of my favourites. I want to explore putting up a small 3-element yagi on one of the towers so that I can at least play around a bit during this summer's sporadic-E season. First I will have to address antenna interactions and mechanical barriers.
  • Computerization: Inside the shack there is a lot I can do to improve operator performance and flexibility with an investment into software and hardware. The present ergonomics are barely passable for contest operating.
There will also be a lot more exploration of antennas and related topics by means of computer models and other investigation. Even if I can't build much more in the near future that does not mean I can't plan, or at least play with various ideas. When I think these are of interest I will share them on the blog.

Longer-term outlook

I have a decision coming up if I intend to have better and bigger antennas: build a large tower on this property or move. Both alternatives have their pros and cons, plus large impacts on non-amateur radio aspects of my life. As someone looking to retire early I do have the flexibility to consider another QTH, one removed from my current personal and business networks. That is, if I decide that amateur radio will be a large part of my post-career life.

Like everyone, I'm not getting younger. If I want it and can do it, it is better to do it soon and enjoy up to 20 to 30 years of playing with towers and antennas and pursuing operating objectives. This might be the year I choose.

This blog

In my travels around the internet I find that most hams with an online presence choose to organize their web sites by topic or project. Those with blogs, either alone or with an accompanying a web site, seem to quickly abandon them.

I seem unusual in that I do everything in a blog. There are advantages and disadvantages to this approach. For example, if I update my experience or further research on an antenna I do so in a new article, not by modifying the earlier one. Of course I link to earlier articles where it is informative, but if you come to my blog by way of searching out the original article you might not discover the updates. As to typos...well, they happen and are rarely worth the effort to fix in already-published articles.

Despite that deficiency I have a strong reason for sticking with a blog. That reason is narrative. I believe that any passionate pursuit, be it amateur radio or anything else, contains a story. The story is often more compelling than any individual milestone or set of milestones. From what I've seen I can assume that many others would disagree, and they do so by documenting various technical or construction projects rather than why they do what they do. Typically these pages are not updated. In fact you get little insight into who these hams are or even if they're still alive!

So I will continue to focus on narrative, for which a blog is best. I recommend the use of the search function provided by Google at the top of the page to find articles relevant to specific topics. That way the blog can still be useful to those who want to find articles on specific areas of interest and care not at all about the narrative.

Dark corners of the internet

For the vast majority of my audience the following message can be skipped. It is for the small number of bad actors lurking in the darker corners of the internet.

Copies of a number of my articles can be found elsewhere with authorship removed or no links to the source material. This is unethical at best and is illegal in most jurisdictions. I spent many years of my career dealing with intellectual property matters so I am no naif. I know it happens. I am disappointed to see hams do it to other hams.

Dealing with it not always easy, so I continue to observe and consider the matter. The internet which creates this problem also makes it easy to discover that it is occurring. That is, I know where you lurk.

On the brighter side, I do welcome fully-attributed references to my articles. In return I make every effort to attribute both online and offline sources I use or extract from. That's only right.