A teacher affects eternity; he can never tell where his influence stops.
—Henry Adams (1839-1918)


Antenna Jargon
And Some Notes on MS Vista

By Jack L. Stone, Publisher


INTRODUCTION
astering the language of antennas is one of the first steps in deepening our understanding of these essential radio devices. Antennas, however, have a highly complex history made up of theory, measurement, construction, promotion, and much else. In addition, antenna language is inseparable from the more comprehensive language of radio communications, which itself ranges from slang to the concepts of fundamental physics. Little wonder, then, that many a newcomer to antennas fails to latch onto the correct ideas behind the words or to connect all of the word-dots into a coherent picture of what antennas do.

Amateur radio literature—which has never been far removed from commercial practice—has historically abetted the problem. In the 1930s (and unfortunately, even today), authors dubbed their antenna creations (in fits of cuteness) as signal eruptors, sprayers, and especially squirters. The last label itself has an interesting history, since it derives from the practice of Hiram Percy Maxim of the ARRL to call new amateurs “young squirts,” in contrast to the venerable label applied to experienced radio operators: “old man.” The proper antenna for a young squirt was a signal squirter.

Most early antennas received names that depended on the antenna’s appearance, not its operating principles. The alphabet was a popular source of names, with B, C, H, L, N, V, and W being the most popular look-alikes for antennas. In fact, it is quite possible to build antennas that look like virtually any letter of either the Latin or the Greek alphabets. Famous names could equally hide the principles behind an antenna, and for a long time, some books divided the world of antennas into Marconi (verticals) and Hertz antennas (horizontals). In amateur literature, some call signs received immortality in the name of an antenna, such as the W8JK and the HB9CB, which only accidentally happen to have a closer relationship than most people initially realize. Some antennas have geometric designations, such as the loop, the quad, the delta, and the rhombic. More heavenly is the halo, and more gustatory is the fishbone.

LABELS
Antenna labels are only a small part of the checkered history of antenna word use. Some terms, like SWR (or VSWR) derived from measurement techniques out of which they emerged. One might argue that the idea of a standing wave as used in the idea of SWR may not exactly coincide with its use in basic antenna theory, but the origins and long-standing use of the term in practical antenna measurements means that it will persist. Indeed, modern instrumentation may now read out in terms of coefficients of reflection or return loss numbers rather than SWR, although it is possible to graph each of these over frequency with the same line and change only the labeling of the Y axis. We shall not pause to consider whether return loss requires expression as a positive or a negative quantity.

Some terms may be condemned to perpetual confusion, such as the ideas of forward gain and directivity. Despite having rather rigorous definitions, common parlance often uses one for the other. Other terms have yet to receive anything close to universal definitions. In the field of directional antennas, the ratio of forward to rearward radiation strength has several different measures and an interesting crossing pattern of labels. The 180-degree front-to-back ratio is the easiest to derive, but sometimes the most misleading of front-to-back comparisons. The strongest rearward lobe versus the main forward lobe defines what some call the worst-case front-to-back ratio and what others term the front-to-rear ratio. However, some refer to the ratio of the forward lobe to the average of the rearward radiation by the same name: the front-to-rear ratio, while others call this measure the averaged front-to-back ratio.

Even the basic labels of some antenna types create understanding problems. Many a newcomer meeting his or her first Yagi antenna thinks that a reflector reflects and that a director directs in the fashion—however vaguely pictured—of an optical system consisting of a mirror and a lens. To make matters worse, there are some antenna systems that use reflectors whose principles in fact derive from optical principles, such as planar, corners, and parabolic antenna systems. Newcomers do not realize that in a Yagi-Uda array, the labels are conventionalizations with meanings having little relationship to the mental pictures that the words conger. How misleading that misconstruing labels can be is shown by the fact that many a seasoned veteran in antenna work almost automatically identifies a longer element as a reflector, even though in some designs, it may not have that function at all.

The problems of labeling do not apply solely to antennas themselves. Some articles refer to any unshielded transmission-line indiscriminately as parallel line, ladder line, window line, or TV lead-in. Likewise, for some, any cable with shielding becomes coax, even if the line is actually a shielded line pair. Recently, we had occasion to alert newcomers to the need to separate some device functions, such as converting a balanced to an unbalance line, transforming impedance, and attenuating common-mode currents, since sometimes we might use one device to do all three tasks and at other times might select a device—such as a choke or a conventional transformer—to do only one of them.

Through the maze of antenna and feedline terminology, which ranges from jargon and argot to honorific labels to practical terms to theoretically founded concepts, both newcomers and seasoned antenna experimenters must wend their way. In theory, we might provide a master glossary of terms and their “proper” meanings, but such a task is fraught with dangers. How much radio and antenna history do we include to explain how words acquired their current uses? How much theory do we include to correct or to exclude misuses of terms? The task becomes co-terminal with writing a basic text. Like all such texts, the volume would find its critics. And few of the folks who most need it would actually use it. Recently, QST has added a glossary for the articles in each issue, with the editors’ judgments on which terms in the articles might elude relatively new radio amateurs. Even that finite and laudable enterprise has gaps for some readers.

NO EASY WAY
There is no simple route to the mastery of antenna words, labels, and concepts. Experience alone may be the best guide—and even here, the kind of experience trail that one takes may bias the result. The measurement technician or engineer may end up speaking a somewhat different dialect of antenna language than the mathematical theorist. The highly varied content—from theory to practical device—in the articles in each issue of antenneX allows our readers to sample almost all antenna-language accents. Careful reading and well-formed questions to the authors can together go far in clarifying the terms. Out of these useful habits emerges a mastery of antenna language. But all such mastery is relative. Because the language of antennas is steeped in its own history, perfect mastery of all terms on all occasions may be more than one can achieve. Our salvation from this imperfection is the fact that—no matter how extensive our experience with antennas—we can always ask another question.


WIN-VISTA: New Pane or Pain?
The answer to both is yes, but is a matter of degree for each situation. There are too many variables out there of machines and software used to be very specific in the individual reader's case. I can only relate to my own experiences since installing on two different machines a 32-bit CPU and a 64-bit CPU machine. Both are very recently built machines and the 32-bit being the newest with a "Vista-ready" CPU. Be advised to not rely too heavily on that Vista-ready claim by the vendors either. You may need to flash your CMOS with the latest update available from the website of your Motherboard vendor to make things work fully.

Don't be surprised to find out if the CD that came with your PC or Motherboard will not run. Your machine just may not be able to handle Vista and that's a basic hardware issue that may mean you are SOL. Software issues may or may not yet be solvable either until the vendor does some updating, but at least not as fatal as the hardware issue. If you really want/need to upgrade to Vista, you may have to consider a new machine, but do your research first to see which brand is reliable for this migration. If you purchase a new PC that comes bundled with Vista, then you should be okay on the hardware side. However, you may not yet be out of the woods on the software side. If your vendors are promising a reasonable and suitable date for update, then you are good to go. But, some undercapitalized 3rd-party vendors may just throw in the towel after just going through all of the previous Microsoft major OSes. Win2k was a great leap from previous versions of Windows and it caught many of the major vendors without drivers/fixes and there emerged a chaos of patched versions that sort-of worked. It is a little better with the 3rd-party support on the jump to Vista but much yet to do. Win-XP was not so major but still had issues.

Here we build all of our machines from scratch, thus, we try to choose the latest components carefully and only install clean installs of Vista to minimize the problems. However, that does not cure the software issues, some of which work but have a mix of performance issues. This includes some of our major software needed. So, we are running workstation machines with Win2k right beside the Vista machines and when some surprise is experienced, we just turn to the good ole Win2K machine to save the day all workstations being on a LAN, we can run/share the same files and not skip a beat while we wait for the few Vista issues to be solved. We had to do some of this way back when Win2K first launched. BTW, Win2K Pro has been used here without a single crash! While a machine may have worn out, Win2K just kept on ticking!

Those who desire to see if their present machine(s)/device(s)/software will run Vista should first run the "Windows Vista Upgrade Advisor" available from Microsoft presently found at this direct link:
http://www.microsoft.com/windows/products/windowsvista/buyorupgrade/upgradeadvisor.mspx
...or, this Vista Home Page:
http://www.microsoft.com/windows/products/windowsvista/default.mspx

You will note that the above analysis process will scan your system and attempt to help you decide which version of Vista is best for you. We selected the "Business" version as we only use UNIX for our servers which was in agreement with the Advisor's recommendation.

As the MS site states in its Overview of the advisor, Windows Vista Upgrade Advisor will help you determine if your current PC is ready for an upgrade to Windows Vista. It will also help you to choose the edition of Windows Vista that's right for you. Download the Upgrade Advisor to run an analysis of your current PC and use the detailed feedback to ensure that your PC is ready for the edition of Windows Vista that you want. But, be aware that you must be running Win-XP Service Pack 2 to run the advisor. As you progress through the above page, you will see other info and tools vis-à-vis your setup's ability to handle the upgrade. I found it to be very useful and it located the same issues on each of our 32-bit and 64-bit machines. It declared there were no known system issues, but one device issue and two program issues.
 

Below is a screenshot of one of the Vista advisor summary reports we ran:

Clicking on the various "See Details" buttons then reveals the specific issues. Here's one example of ours:

As you can see, some very helpful details to get up and running. And believe me, when the advisor says it sees those problems, it means it.

I cannot stress strongly enough how important it is to run the advisor as it will probably save you from experiencing a good deal of misery if you try to upgrade in the blind. Even so, once we slipped in the Vista CDROM, almost the first thing it did was recommend it check online for any updates for the installer -- sure enough, it found a new version and it found another problem, not seen by the advisor, that would need attended to after the install. Luckily, it didn't say anything more serious than that and the install went forward and went smoothly.

No more Outlook Express! You will find a "Windows Mail" program installs with the Vista OS, but it is NOT the old OE that has survived throughout most of the previous versions of the Windows OS. We are now using the new version and it seems to have a new look and feel with different features but no drastic changes noted. Not sure if your old OE messages saved is compatible as we haven't yet bothered with it. We'll see later if an import is possible.

Office 2003 installs okay and comes with it's "Outlook" email program. With exception of FrontPage-2003, all of the other programs (that we use) run okay. FrontPage loads and appears to be working fine, but suddenly stops working and unsaved work is lost. This version of FrontPage works okay on our Win2K & XP workstations just fine. Alas, this may not matter as Microsoft has stopped supporting the FrontPage extensions for UNIX OSes and no further versions have been produced since the FP-2002 version. Funny though, FrontPage runs better on UNIX than Window servers -- much faster. Guess we'll have to start experimenting with Dreamweaver and say adios to FrontPage. It's probably best anyway as many if not most UNIX admins found FP to be vulnerable and very difficult to install/maintain.

We had to buy a new graphics card that claimed to be Vista ready, but upon install of the card, we found that Vista did not like and would not install the software needed to run the card -- however, Kudos to Vista. It did save the day by asking if we wanted it to search for a new compatible version online. Amazingly, it took us directly to the vendor's download page for the new drivers -- which had been made available only that very same day! Got lucky. Did the download, installed the drivers and all was good to go. Just happened to be a major vendor that was on the ball just in time.

Adobe says that Acrobat 8.0 will "run" but has some issues -- in other words, not quite ready. Adobe Reader 8.0 does run okay though. These programs are an essential part of our publications.

On the 64-bit machine, Internet Explorer 7.0 runs just fine, but on the 32-bit machine, it locks up. FireFox runs great on either machine. Prior to the release of Vista, there has been complaints about MSIE-7.0 running too slow and we found that problem here as well on Win2K -- in fact, it would lock up at times there too. Some say MSIE-7.0 had been written (or recoded to some extent) in anticipation of Vista and may account for the ills of late on earlier versions of Windows.

Overall, we have a few software issues to resolve, but to my pleasant surprise, most of our programs run fine whether 32-bit or 16-bit, many several years old. Vista's DOS shell runs all of our old batch files without complaint too. Moreover, Vista shows good stability over the past 2-3 months since the first install. Basically, it's just subject to install and hope for the best—and it may take awhile for an issue to show up if at all.

One aspect that is a bit troublesome at first is the very tight security now one of main the changes. Of course, loose security always has been one of the main complaints about Windows, especially servers where MS would like to increase their share of the commercial business. There are lots of knobs to find to handle the proper settings for sharing files on a network or other access. Although we solved it with some effort, it's only when writing this I found the same solution on the Vista forum mentioned below. Should have taken my own advice!

According to some recent reviews, doubt is expressed that Vista is any more secure than XP. Here, that is not a concern as my UNIX gateway does the filtering and we don't rely on Windows for security.

It's a pretty steep learning curve with things/features moved around and many things not in the same location that we are used to, especially when moving from Win2K -- not quite as big a leap as from XP. At least one has a choice in Control Panel to use the new view or the classic view which helps a bit as the CP is one of the most essential places on Windows when managing the OS.

A good Windows forum for those seeking help on specific problems or to learn from the experiences of others when researching the feasibility of upgrading is at:
http://www.computing.net/windowsvista/wwwboard/wwwboard.html
And, here's the "permissions" tip page:
http://www.hardwarecanucks.com/vista/1008-how-share-root-drive-under-vista.html

On the above forums, you will find a mixture of opinions about moving to Vista. Of the negative ones I read, most all were upgrading from XP and saw little change. However, I believe a lot of those were hasty opinions and some were from frustration of having to learn some new behaviors.

Some other reviews may be found here (thanks to Gary Nixon):
http://www.theinquirer.net/default.aspx?article=39926
http://www.crn.com/software/199701019

The permissions were the biggest pain of this new Windows' Pane! The rest is fairly routine installing and the usual configuring issues aside from discovering a very few programs that don't yet work. Windows 2000 Professional served us well from the day it was installed and found everything ran reliably and the OS was extremely stable and able to run all 3rd party applications needed here.

By the way, in follow-up to my complaint above about FrontPage, while writing this, I tried it again on Vista and got in, did some editing, etc. and exited without a problem my guess though, the problem is still lurking there as I didn't have as many open sites on this trial—or perhaps some combo of apps running at the same time—only time and practice will tell.

Those out there running complex modeling programs may experience problems. If you can afford to keep another machine that runs all of your present programs, it's a good idea to do that and slowly migrate each of your apps as and when fully tested. This should minimize the misery factor.

For our needs, I am happy with the upgrades even though our experience has been brief. Moving from Win2K is a bigger change than from XP though. I did not see any benefit to upgrading to XP (although it looks nicer than Win2K), but I do believe Vista has good potential, especially the 64-bit version when more programs become available to use that architecture (yes, XP has 64-bit too).

Your individual experience with an upgrade, even using the bundled version, is likely to be different than ours or for that matter, any others because of so many variables in hardware/software configurations. The best advice I can give is not to judge Vista too hastily and rush back to XP or other older versions only because you may need to learn some new tricks—we run the risk of missing out on some new applications yet to come. Good luck!

Ooops! FrontPage just crashed again! The good news is that I didn't lose anything as I have been saving this file every few minutes. MSIE-7.0 still doesn't work, but FireFox is fast! MSIE appears to be having a similar problem to FrontPage—"this program has stopped working." With MSIE, it asked if I would like it to look for a solution—I clicked yes, but it never came back! On FrontPage, it takes me to the MS Office download page, but there are no updates suggested. More time needed!

UPDATE ON SOLVING ONE ISSUE
Just solved the problem with MSIE. It was some sort of problem with the browser plug-ins or add-ons as labeled here by Microsoft (Foxfire calls them plug-ins). First, I analyzed the Event Viewer in the Administrator Controls and found the long list of errors dealing with the Internet Explorer application. That led me to the MS Knowledge Base which discusses all kinds of problems. I spotted one that dealt with add-ons which led to the location of how to manage them. The suggestion was that a plug-in might be in conflict.

After locating the spot buried deep within the Control Panel, I saw one obvious issue: a dual install of the runtime Java. I deleted one and launched MSIE—nope, although the dual install was wrong, MSIE still launched then stopped as usual.

Okay, let's get tough! The add-on manager provides the ability to disable/enable the add-ons, so I decided to disable them all and then enable them one by one and see if that approach narrowed down the issue. Sure enough, it did and after several dozen restarts of MSIE after adding back an add-on, voila! It now works!

I'm providing all of this detail in real-time (while still writing this column) because it's the kind of things some may expect to deal with—and can account for some to give up and go back to the older system. Just keep looking and you'll eventually find the answer. You may have to give the debugging effort a rest for awhile and then try again when feeling a bit fresher and not so exasperated.

Hmmmm....wonder if this solves my FrontPage issue too. Guess I'll know soon enough!


THE PURPOSE OF THIS JOURNAL
In my column for September 2006, “The antenneX Mission,” I wrote about a subject close to my heart — the purpose of this journal. It had been quite some time since I had reminded our readers of our original purpose when we set out some 20 years ago.

More than anything else, this journal has always been a “labor of love” for me. It is the reason I founded the antenneX magazine almost 20 years ago, knowing that running a magazine is a tough business and especially so since I planned to do it without the traditional revenue support from advertisers or outside investors. I wanted this magazine to always be able to write about any issue without concerns of losing the support from any of those type revenues. I am pleased to say, we have never steered from that course one iota. And, as a consequence, we have covered some very controversial developments throughout the past two decades. In the process, we have provided valuable factual information to more than 200 countries, even to the most remote regions of the globe. Hence, our readers are much more informed about the truth about all of the “new” devices  as their stories unfolded in the antenna and antenna-related field. For more details, you are encouraged to read my column from September 2006.

Additionally, we were pleased to receive and publish in the October 2006 issue, a very special editorial reaction to my column written by one of our long-term readers and contributors, Dr. Jef Verborgt. Those two articles are located by the following links below:

arrows_ORANGE_left.gif (577 bytes)| The antenneX Mission | Why Do I read antenneX? |arrows_ORANGE_right.gif (593 bytes)


VISIT THE GUEST ROOMS
The relentless attacks on our web site by pirates and the like has made it necessary to add more security to protect our material against such piracy. It's only fair that we know who enters the House of antenneX, so our guests will need to provide some minimal information in the process of obtaining a login. This includes using your real active email address without which a login cannot be received. Do not confuse this login with a paid subscription login. They are not the same and your subscriber login will NOT work in the Guest Room areas. Of course, you may choose to create your own login to the Guest Rooms using the same login as your subscription, if the system will accept it.

Along with the continuing fight against spam/virii junk, protecting our material and valuable bandwidth against piracy takes up a great amount of our time—time we can't really spare. The Internet is simply not the friendly neighborhood it used to be in the "old days" and more and more security must be installed to counteract these intruders. Thus, we have made the access to the Guest Rooms as automatic as possible for you to manage your own login.

http://www.antennex.com/guests.html
wpeD.jpg (85196 bytes)
http://www.antennex.com/guests.html

In view of the above, we have overhauled the numerous free and open-access sections that have always been wide open to all of our friends throughout the many years antenneX has been online. But, we must change with the times as the need dictates. I don't think the Internet will become more friendly in the near future and protected sites with logins are fast becoming the rule rather than the exception. To repeat, most would like to know who they invite into their house. The same applies at the House of antenneX. It's really worth the effort!

This list pertains to those sections with free access now in our new Guest Rooms we have built and fully operating:
• Antenna Science
• Preview Articles
• Software Download
• Antenna Modeling
• From the Shack
• Propagation
• Ham WorkShop
• Stone's Throw!
• Discussion Forums
• Patents (new room under construction)

We have activated a new login system for access to the above guest rooms — and, the login can be totally managed by our guests. Above is a graphic of what you see as a login page to the new consolidated area, "antenneX Guest Rooms." This new page for logins is at this location now and available for your use:

Get your login all setup now at this URL:
http://www.antennex.com/guests.html

We've really tried to make it easy while still fending off the bad guys, i.e., pirates!

As a result of this new programming, you will be able to obtain your own login, change it to update your info, change your password and delete membership if & when you desire without our help. Of course, the bottom link on the new page provides help if you still need it.

If you still need help or have questions about our login areas, check this page first:
http://www.antennex.com/help/need_help.html


The new Antenna Discussion List is a infinite fountain of ideas making it a great "watering hole" for exchange of ideas, questions and answers on a wide range of antenna-related subjects. You will be in good company along with some of the brightest minds available. Were else would you have such free access to this level of expert advice? To participate or just read along on some very interesting subjects each month with 2000+ members from all around the globe, you are welcome to join us:

arrows_ORANGE_left.gif (577 bytes)| To Antenna-Discussion Archive | To Join Discussion List |arrows_ORANGE_right.gif (593 bytes)

You are encouraged to contribute your thoughts on various subjects to a worldwide audience.


AN INVITATION TO CONTRIBUTORS
wpeE.jpg (5756 bytes)antenneX thrives on the contributions of antenna experimenters, ranging from the informal home shop construction project to the theoretical investigation of basic antenna, feedline, and propagation phenomena. Over the years, we have published articles on the use of new or newly adapted materials, known antennas adapted to new circumstances, modifications of antenna structures, basic explorations of both common and unusual antennas, antenna modeling exercises, design improvements, antenna matching techniques from both a physical and mathematical perspective, evaluations of mini-antennas and their underlying theory of operation, new and patentable designs, propagation tutorials, and.... The list goes on, since no antenna-related topic is irrelevant to the readers of antenneX.

At the same time, antenneX has experienced continuous growth in its readership—for which we are appreciative. However, all readers can help us do even better. How? By submitting an article every now and then based on your current antenna work that may be useful at any level to other readers.

Among the engineering and researching readers, there are undoubtedly a number of unclassified and non-proprietary findings that antenneX readers would like to know. Among the practical antenna designers, there are ideas, tests, and numerous other practical findings to benefit our readers. Antenna builders very likely have some techniques to share with other readers. Besides the regular articles, we always have the home work shop column for shorter practical ideas and we always have the invited news and editorial column for information about new technologies, future advances, lost old but good ideas, and personal views on the good to bad things that are happening in the world of antennas and propagation.

If you are uncertain about whether your ideas merit an article, please feel free to send an outline to the general editor/publishers at
manuscripts at antennex.com . Do not feel that you must be ready to be a regular submitter to write for antenneX, because we welcome the individual contribution as much as monthly articles. As well, do not believe that the slots in each issue are already spoken for—we shall always make room for a worthy article.

To see details of our writing guidelines, please look at: Writing for antenneX


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IN THIS ISSUE
We again include many fine articles by our great writing team from around the globe. Now, allow me to introduce this month's line-up of content:


OUR MONTHLY COLUMNS (plus this one you are reading by yours truly):

FEATURE ARTICLES IN THE LIBRARY:

Notes on the Extended Aperture Log-Periodic Array
Part 1: The Extended Element and the Standard LPDA

By L. B. Cebik, W4RNL

In the R.S.G.B. Bulletin for July, 1961, F. J. H. Charman, G6CJ, resurrected a 1938 idea for antenna elements developed by E. C. Cork of E.M.I. Electronics. The elements are variously called loaded or extended wire elements. Charman increased the length of a center-fed wire to 1-λ while still obtaining a bi-directional pattern and a usable feedpoint impedance. He inserted capacitances between the center ½-λ section and the outer sections, thereby changing the current distribution. After a brief flurry of HF and VHF antenna ideas, the technique fell into obscurity, although the basic concept is related to certain collinear designs that use an inductance and a space between sections to obtain the correct phasing. I am indebted to Roger Paskvan, WA0IUJ, for sending me the relevant RSGB materials on the Charman element.

Bessel Beams
By Kirk T. McDonald, PhD
Joseph Henry Laboratories, Princeton University

This paper's focus will deduce the form of a cylindrical symmetric plane electromagnetic wave that propagates in a vacuum. A scalar, azimuthally symmetric wave of frequency ω that propagates in the positive z direction will be formulized.

Then the problem is to deduce the form of the radical function and any relevant condition on the wave number kz and to relate that scalar wave function to a complete solution of Maxwell's equations. The waveform has both wave velocity and group velocity equal to ω/k. We shall comment on the apparent superluminal character of the wave in case that kz < = k ω/c, where c is the speed of light.

As the desired solution for the radial wave function proves to be a Bessel function, the cylindrical plane waves have come to be called Bessel beams following their introduction by Durin et al. Thus, Bessel beams are a realization of super-gain antennas in the optical domain. A simple experiment to generate Bessel beams is described.

Baluns and Antenna System
Network
Impedance Matching, Part IV

By Fred M. Griffee, N4FG (EE Retired)

Some of my past articles address the T, Pi, and L matching network design process. The Pi matching network essentially includes the L network possibilities and therefore is somewhat redundant regarding efficiency. However, it is recognized that the L matching network can be the most efficient if the needed component values can be experienced. Some analysis addresses this area.

An auto tuner will be included that uses the L-network matching process. Its included memory that can be used to recall network matching component settings for a particular frequency and load is of high interest since it reduces the tune-matching process to seconds – a desirable factor when a need arises to change bands rapidly.

Manual tuner matching shall be addressed, and the relative time taken after calibration for a particular antenna system. Time is of little interest to many but the amount of time over an extended period, and the boring process of adjusting components to their settings becomes laborious.

Straight lines, circles, and AC theory
By David Jefferies

This article is intended to provide a beginners’ tutorial on complex numbers and AC theory. It seems only yesterday that I was sitting the Radio Amateurs’ Exam in the UK and tangling with inductance and capacitance without the benefit of the mathematics of complex numbers. I think this was 40 years ago, and I can still remember knowing just that “a capacitor (condenser) blocks DC but passes AC” without being able to put numbers to this phenomenon, even though I had memorised the formula for the ‘reactance” of inductors and capacitors.

I survived in this state of hazy ignorance until after my graduate school days, about 16 or 17 years later. Then I got involved in trying to compute the amplitude and phase response of low pass filters intended to suppress the “birdies’ in an FM stereo decoder. At that point, the AC theory and the maths I’d learned in University both came together and I realised what I’d been missing.

So this article is aimed at people who might wish to know what Real and Imaginary mean as applied to impedance and voltages, and what amplitude and phase shift mean in an AC waveform, and how they can be visualised from knowing the Resistance (“real impedance”) and Reactance (“imaginary impedance”) of a component or circuit.

A Day at Dayton
Dayton Hamvention — 2007
By Tom Cox, KT9OM

This year, I promised Jack Stone, head honcho at antenneX Magazine that I’d take some pictures. The tradition among the group of geezers (and honorary geezers) I do Dayton with (and yes, I count myself among the geezers) is to find any pretext to take Friday off work, rise before dawn, and reconnoiter at a local parking lot. Everybody crawls out of his own car and into the van, bus or SUV of the volunteer driver, and off we go. The ride over is almost as much fun as the destination, as we swap gossip, insults, lies and jokes, often in combination. The crew this year consisted of Frank, WA9COP (this year’s volunteer driver), Greg, N9DEZ, Norm, K9BUL, Bret, K9BUZ, and your humble correspondent.

Being an antenneX antenna aficionado, and not being particularly flush with spending money, I had plenty of time to wander the aisles, inside and out, checking out the antennas and antenna-related products and taking pictures. One of the more striking sights at Dayton, at least for this pilgrim, is the display of antennas in the Hara Arena, a large, high-ceilinged room that also serves as semi-pro hockey rink. One seldom sees a multi-element, full-size HF Yagi set up indoors, but this is the place to see one, along with full-size verticals, wire dipoles, and a shiny forest of VHF and UHF verticals. Take this pictorial tour with me for the 2007 show #56 at the Dayton Hamvention.

The PF4 Antenna Tested
By Dave Cuthbert, WX7G

Two months ago Bill Graham, VE3ETK, introduced a new and exciting antenna in the pages of antenneX. Bill’s invention, the PF4 Phased Field antenna, is the result of much work and three different models. The idea of such a compact antenna yielding good performance started a lengthy discussion at the antenneX Discussion List. The discussion involved these main issues:

• Is feedline radiation responsible for the good performance?
• Are the radiation fields really phased and combining or is conventional antenna theory at work here?

I decided to build a PF4 to see how well this 2-foot diameter, 14 MHz dipole works and if the performance could be explained by conventional antenna theory. We go over the theoretical aspects of the PF4 and then we look at actual field measurements of the PF4.
 

Well, there you have it, folks—thanks for listening and remember, the reading lamp is always on for you in the reading rooms. If I can be of further help, I'm just a Stone's Throw! away.-30-


Best reGARDS, Jack L. Stone, Publisher
jack@antennex.com

June 2007 antenneX Online Issue #122

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