HAMS & SPAMS

ast month I discussed the modern tools in the fight against SPAM that have evolved recently and attempted to explain how they work and at the same time, debunk some of the myths as well. Many “letters” were received with appreciation. The issues surrounding this subject continue to grow and how they may affect the current e-mail system is further discussed this month. Although we are about antennas, this dynamic “new” media that is always in a state of change, carries us from our door to yours and we should discuss anything that affects it. However, before getting into that subject, let’s talk some HAM and other antenna issues.

TESTING THE EH ANTENNA ARTICLE
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In the previous month antenneX issue #70 for February 2003, we published Part 1 of the series of articles, “Testing the EH Antenna” authored by Claudio Re, I1RFQ of Italy. Thousands of copies of the article were downloaded indicating a strong interest from our readers. I suspect this is because there has been a lot of talk about the EH and its claims over the past three years, but this was the first time anyone had made an effort to perform tests, make real measurements and report them publicly.

Part 2 of Claudio’s series appears in this month’s issue and it goes into great detail about the open field controlled test range results. Claudio is well qualified to perform such tests and I think it bears importance to repeat his qualifications, if this is his first introduction to the reader:

BRIEF BIOGRAPHY OF THE AUTHOR
Claudio Re, I1RFQ is a graduate of Polytecnic of Turin in 1980 with specialization in “Telecommunications and Hyperfrequencies“. He is an owner of Sistel SRL and Sinfotel SRL, two small telecommunications, companies in Italy. He is also a consultant and the Network Director of the World Family of Radio Maria, a Catholic Broadcasting Network that broadcasts now in 27 different countries of the globe. He has experimented with all kinds of equipment from 136 KHz to the optical frequencies (one-way communications at 22km)

You are encouraged to read Part 2, because this is where the EH Antenna is defined by Claudio following his extended efforts to understand the device prior to making a decision to buy the commercial unit. He first performed tests on the EH he built and then on some factory-built versions furnished by one of the promoters. His findings are rather dramatic and conclusive.

NEW LOW-PROFILE BROADCAST ANTENNA CONCEPT?
As I’ve stated so often, many out there are in search of ways to “shrink” the profile (size) of antennas. This endeavor applies to all markets whether, amateur, commercial, military, civil, etc. It was recently brought to my attention that the Star-H Corporation has weighed into this arena and is testing their version of a low-profile (reduced-height) MF Broadcast Antenna on 1680 kHz in Tennessee, USA (my thanks to Dave Cuthbert for bringing this to my attention). The interesting part about this news is that this concept appears to operate on "standard EM theory" and doesn't claim to be an offshoot of the EH or CFA antenna.

The claims are that this antenna is approximately 98% as efficient as a standard quarter wave monopole antenna, but is less than one-third the height. The further claim is that this is the most efficient reduced-height antenna design available today. What is even more intriguing is that they also show evidence of taking measurements to back up the claims!

According to their reports, the radiating efficiency of the KinStar antenna has recently been proven as a result of a series of full-scale tests that have been conducted at a power level of 250 watts and frequency of 1680kHz under FCC Experimental License No. BPEX-20020910ABK in which case a complete FCC six-radial proof of performance was conducted on both a quarter wave tower and two configurations of the KinStar antenna all on a standard 120-radial quarter wave ground system.

They have a web site that provides some information about this project and I reprint some of it here for your convenience. For further information, it is suggested you visit their web site at: http://www.star-h.com/products/reduced.html

Now, this sounds like a professional approach and we’ll need to keep our eye on their progress as we work toward finding the "Holy Grail."

RF NETWORKS DESIGNER SOFTWARE
Recently, we announced the availability of Grant Bingeman’s RF Network Designer program. A compressed trial demo version was presented for free downloads. The file size was approximately 1MB and could be downloaded fairly fast. However, it became obvious quickly thereafter that the demo was difficult for some to install because of the various versions of Windows and the Windows “system” files needed to run the program.

We looked for some better way of installing the demo and in that connection, Grant provided another demo version that was a “self-installer” that could do all of the work and eliminate the need to download the extra “system” files that might be necessary to successfully run the program.

However, the new self-installing demo file size has grown from 1MB to 13MB. For some with fast connections, that is not a problem. But, for those with the slower connections who prefer a different method of trying the program, we have now produced the demo and made it available on CD-ROM so it may be shipped to your door as an alternative. For more info on these new developments, please visit this URL: RF NETWORKS DESIGNER

DOUBLING OUR BANDWIDTH
During the past month, especially after making the announcement about the new software 13MB demo, plus the inordinate amount of downloads of the 2MB EH Antenna article, for two days following the announcement, our server's bandwidth consumption was doubled and we noticed a slow down. This is also because our traffic continues to increase each month. To facilitate the growth in bandwidth consumption and speed up things, we have made arrangements to double our bandwidth capacity from our backbone connections. This increase in BW capacity should occur and become noticeable within the next couple of weeks in order to better serve our readers.

SPAM BLOCK OVERKILL?
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In my previous column, I went into great detail about our recent installation and application of the UNIX version of the SpamAssassin program on our main mail server to identify and tag suspected SPAM. It doesn’t reject or bounce any e-mails it only tags it so the end user can may the final decision of what to do with the e-mails. It is a very sophisticated weapon to use in the fight against the relentless and annoying floods of SPAM that anyone with an e-mail address has had to endure with increasing volume during recent months.

It is now with great relief to observe that finally, many of the mail servers at the various ISPs are doing something about this issue to slow down the floods of SPAM and have now employed the use of spam-fighting tools similar to SpamAssassin. Alas, though, as happens so often, the new weapons and tools are being used to extreme, or so recent results are indicating. It is because we manage our own mail servers we are able to see some of this first hand.

Even at the “weapon” reflectors, we see a disturbing attitude toward the employment of the new “powers”. One very disturbing, if not naīve effort is that of “bouncing” the SPAM. The reason this will not work and not a good idea is because the “sender” is usually phony or forged in which case an innocent party is a victim of being e-mail “bombed” from the bounce-backs from all of those mail servers. Further, doing that only serves to use up more valuable bandwidth on the already congested Internet.

Other mail servers take a very loose if not lazy approach and use some very broad methods of identifying suspected SPAM. For instance, with some servers if too many recipients on a single message hit the server that makes it SPAM and it is denied access. But, a good example of where such approach is wrong is the classic case of the poor little Church group that made regular mass e-mailings of announcements to their group of members but were suddenly denied access through their mail server relay. No amount of effort worked to convince the server that they had legitimate need to communicate with their members and it was not SPAM. Only moving to another ISP solved the problem. The problem here was mainly because the ISP handled such a large volume of e-mails, they looked for the simplest “handle” they could find to tell their computers to be on the lookout for—and, just not enough “human” resources available to deal with such individual issues when tens of thousands, or maybe millions of users are involved.

Apply this blocking example to many other legitimate bulk e-mailings that are a regular method of conducting business, then we have a very unhealthy trend in the other direction and a problem worse than the SPAM. Perhaps the pendulum now swings too far to the right!

Believe me when I say I understand the attitude toward SPAM and the first reaction is normal to want to jam it right back at the source with equal force—if only it were that simple. Or, just simply block anything that might smell like spamming without analyzing it to see for sure. But, doing so defeats the main purpose of the e-mail system—effective communications.

Because we must announce when a new issue is ready to read, antenneX is one of those “bulk” e-mailers of the type described and on occasion, our own e-mails suffer a denial of service through some server because the server sees the key word “bulk” in the header or hits the “too many recipients” filter. A determination of what qualifies as “too many” usually enables a pass-through. Either that or a discussion to resolve the problem with the Server Administrator, if one can be reached.

Managing a mail server these days is not as easy as it was a few years ago when the Internet was a friendlier place. I do not envy the responsibilities the ISPs must bear under these “war-like” conditions. While applying a heavier hand toward the floods of unwanted e-mails, the ISPs must find a balance in the use of the new powers that also is fair to the users. One day the pendulum will swing back towards the middle and things will not be so erratic concerning the handling of e-mails. We must be patient while that happens and be careful about the proliferation of “spam-fighting” software that is surfacing of late to take advantage of yet another new market opportunity. Some software may be good, but any that suggests spam-bouncing as a solution is a very bad idea, IMHO. Also, any recipients that use a service that intercepts a message, then responds to a sender and requests that you click on some URL to be "put on a white list" is a scary idea. Any that have dealt with the "You have a Greetings Card" trick with a virus lurking at the other end know what I am referring to. And, to make matters worse, we are now being spammed by the spam-fighting software developers trying to sell us their own products!

Well, I guess we all must find ways to cover our overheads—it's part of the dynamics of business!

LPDAs for the 400-800-MHz Television Range
Part 2: A Practical Antenna
By: L.B. Cebik, W4RNL

In Part 1, we examined a nearly ideal log periodic dipole array (LPDA) for the 400-800-MHz range, which is anticipated by some to be the main home of high definition television in densely populated areas of the US. The antenna showed over 18 dBi of gain with better than 30 dB front-to-back ratio and a beamwidth under 45 degrees throughout its frequency range in either vertical or horizontal orientation, when modeled 20' over real ground.

LAB NOTES: The Size of the Loading Coil
By Joel C. Hungerford, KB1EGI

Last month Joel described the results of plotting the resonant frequencies of a monopole antenna as a function of the position of a loading coil along the wire. It was found that the smallest coil tried, 4.5 uH, showed an interesting pattern that revealed much about the reflecting conditions in the antenna. This month I measured some more coil sizes and made an attempt to interpret the data in order to find some design rules. A loop antenna that I described a while ago was “hardened” mechanically, placed about 20 meters away from the loaded antenna, and connected to the spectrum analyzer in the basement in order to measure the radiation as the coil was moved. The object of all this is to find a way to design the smallest antenna size possible that will still radiate.

Antenna Toolkit - Part 3
By Igor Grigorov, RK3ZK

This series of articles gives instructions for an antenna installation and a lot of necessary “trivialities”. You can find here recommendations for the choice of antenna materials, for antenna adjustment, and for the elimination of stray resonances of the antenna mast and traverse- boom (stray resonance of antenna mast can disable operation of any antenna). Ignoring these “trivialities” can result in damage to the antenna system. Most of these “trivialities” are not reflected in the description of an antenna circuit and antenna construction. The necessary experience for solving these questions comes to a radio amateur after years of installation, repair, and maintenance of many antennas. But do not wait so long! Read this series of articles and build your own antenna!

Testing the EH Antenna: Part 2
By Claudio Re, I1RFQ

In this month’s issue, we have “Testing the EH Antenna: Part 2” of a 2-part series of articles describing in great detail how Claudio went about conducting the tests. It was not idle curiosity. He was interested professionally in whether the EH could live up to the claims for his own applications and wanted to find out for himself. Here was a potential purchaser of the EH who wanted to try before buying. Claudio has kindly shared this information with us in the form of this extensive 2-part article. Claudio first conducted tests on the EH that were constructed by him, and then further tests were made on two factory-made EH devices furnished by Stefano. Thus, we now have independent tests on the real EH, thanks to the efforts of Claudio and his submission of the articles. In Part 1, Claudio described his setup and some early calculations. This month, he presents the measurements from open field controlled range tests and the conclusions reached about the EH Antenna.

MultiNec – MultiProp, Antenna and Propagation Modeling
A Review - By M. H. De Canck, ON5AU

In antenneX, April, 2002, online Issue #60, Dan Handelsman, N2DT, published a review of the excellent Antenna Modeling Software Tool, “MULTINEC” from the hand of AC6LA, Dan Maguire. This was a real bonus to all the radio hams loving antenna modeling. The author has often used it in his own antenna modeling sessions, in conjunction with EZNEC-3. People who thought this was the end of the MultiNec features did not realize what was up Dan’s sleeve or extent of his programming skills. Marcel takes a close look with a review of the latest versions of Dan's software developments.

Compact Antenna: Gain, Bandwidth and Ground Absorption
By David J Jefferies

In this article we suggest that the coupling to ground and adjacent objects sets the gain and the bandwidth of compact antennas, mounted in practical environments, predominantly. The ground absorption does not depend much on the size of the small antenna, but it affects the Q factor which, in turn, limits the gain and enhances the bandwidth. For this reason, many compact antenna installations work better than the limitations of the CHU formula for small-antenna Q might indicate.

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. March 2003 antenneX Online Issue #71
reGARDS, Jack L. Stone, Publisher jack@antennex.com