Things Change
By Jack L. Stone, Publisher
Some people swallow the
universe like a pill; they travel on through the world, like smiling images pushed from
behind.
—Robert Louis Stevenson (1850–94), Scottish novelist,
essayist, poet.
INTRODUCTION
ur initial
magazine format was established based on publishing 10 new articles in each monthly issue
of antenneX: Four monthly columns and six features. The columns were designed to
be written by the same author each month while the features would be a mixture of some of
our regular team of writers as well as submission from authors new to antenneX.
On the other hand, I am very pleased to note that for the past 7-1/2+ years (91 issues online) for the most part our format has withstood the “test of time” very well and antenneX has gotten better and better each month. This is largely because we have been lucky enough to have started with some excellent writers and have kept adding to that base until now we have contributors from more than 25 countries. This very fact has help achieve another original goal of making this truly an International magazine where manuscript submissions are welcomed from anywhere on the globe. This allows us to see the different technical views, approaches, interests and terminology that exist from across those invisible borders.
Another conscious thought that went into the original “stew” was that I wanted antenneX to be interesting and entertaining as much as possible without going so far as to not be taken seriously as a science journal. Again, I think we have scored well on that ingredient based on the feedback from so many readers. It would seem our “bleeding edge” concepts have accounted for much of the entertaining portion, while still presenting a seemingly endless way of redesigning concepts that have been around a long time and “milk” even more performance out of them. This not only applies to antennas but to other components of the “antenna system.”
The above scheme of things has worked well for a long time, although one can reasonably expect to see changes to the best laid plans over enough time—in fact, change can be good and can bring a certain freshness with it.
WHERE'S THE HAM?
One
change you may have noticed is that the Ham WorkShop has been absent for the
past two issues. Also, you may have noticed that when our new propagation column was
launched 2-1/2+ years ago, that exceeded our plans for only 10 articles per month and
brought us to 11: five columns and six features.
At the time of the new propagation column, I had contemplated dropping the Ham WorkShop then, but did not, because it was sort of a “pet” of mine being that it was a basic “how-to” type of column that brought balance to the magazine with all of the other more technical content. Almost everyone will find it necessary to make use of their “work shop” and it’s always good to know some tips and tricks to make that project go just a little easier. This is where the Ham WorkShop shines!
The HWS column really requires a regular writer who possesses a unique talent for problem solving with clever ideas on how to utilize common every day items that once assembled, becomes a solution or alternative to an issue that brings a smile across one’s face once the concept is presented. August Hoecker, W8MIA was such a person and launched his first column in May 1998 and he continued to author the column through July 1999 when his personal life changed radically, including relocation from California to other parts of the USA. Hardly a month goes by that we don’t receive fan mail for Harold.
Richard Morrow, K5CNF, on staff here, is also one of those clever people who never seem to run out of ideas. While we waited to see if Harold would be able to return, Richard picked up the column in addition to his own regular monthly features. Interspersed were other submissions that we received from time to time.
Alas, 1-1/2 years ago, Richard met with severe health problems requiring long periods of hospitalization and extended health care that continues today. He returns to the hospital on November 9, 2004 and we have high hopes the outcome will help him fully recover. If so, Richard should be back in the harness at antenneX making his presence known again through his writing contributions.
Mind you, the above notwithstanding, the HWS may return, especially if Richard is able to return to his normal activities—in the meantime, antenneX still presents its readers with the original format of 10 fresh articles with each new monthly issue. Moreover, as and when we receive an article that really fits well into the HWS format, then we would consider publishing that column on an as and when basis—it doesn't necessarily need to be monthly.
SOMETHING NEW ALREADY!
Actually, there is already a new section, or subsection at least. Perhaps you
have not yet discovered it in the popular Preview Section. Just click on the link below
and browse the treasures there in this new section started quietly several months ago:
The above section is another new idea introduced during this past year of 2004. It is reserved for intellectual works finished and in progress by various authors as and when we find them. As it continues to grow, we may consider a completely separate section for it too.
SOMETHING ELSE NEW FOR 2005?
Whether the HWS returns or not, we are always thinking about other areas of
interest as demonstrated by reader feedback, and especially from the antenna-discussion
list where those interest are very evident. We have noticed there is a great deal of
interest in some the "classics" or hard-to-find articles no longer in print.
Although some of the techniques used in those articles my be crude by today's standards, I
referring here to those where the theories have withstood the test of time.
I have noted several discussions about some of these "classics" that many seek and would enjoy easy access to once again. Robert Wilson kindly scanned and burned on CD-ROM an excellent classic reference which I now have received. Just within the past week, our team writer Fred Griffee's succeeded in his efforts to locate one of these "classics" for some research he was conducting and shared it with antenneX.
Tech Editor, LB Cebik then observed that we might consider replacing HWS with a different feature which might be called Classic Reprints or Library of Classics, assuming that a: we can locate some good items and b: we can get permission to reprint or be sure that reprinting would not violate any laws. Indeed this idea has piqued my interest especially since we are well on our way with some of those classics that would qualify for this "new section." More thought needs to be given to it yet, but perhaps this type of handy unique research library is a good idea for kickoff in 2005.
The more I think about it, the more I like the idea of a good source for finding those classics. I suspect there are many out there who would be willing to donate to this special and unique Library of Classics.
Your feedback on this is welcomed as usual—or any other idea for a new and special section. We can't do them all, but we try.
|
In the past, we have announced upcoming events that might be of interest to our readers. In keeping with that policy, we are pleased to announce another short course at the University of Surrey in the UK that is scheduled for December 6-10 2004. The course, which has been run eight times in the past, is entitled "Antennas and Propagation." The course will give an overview of some fundamental principles associated with RF and microwave antennas and propagation. The course presents underlying theory together with some techniques for practical applications, particularly in satellite & mobile communications. Attendees will progress quickly in these topics, and will review published material in the field, identifying which concepts and techniques are of major practical importance and will be exposed to current practice and recent developments. Topics will include Antenna calculations and Practical Antenna Design:- VHF/UHF Propagation Prediction:- Overcoming Channel Impairments :-HF Propagation and a range of measurement techniques. The course fee includes a copy of the book "Antennas and Propagation for Wireless Communication Systems" by Dr S Saunders. If you were planning a trip to the UK, this would be an activity to consider. If you weren't planning a trip, now you have a reason. If you reside in the area, then you have the advantage. For more info, you are encouraged to look at this
URL: |
TWO MORE COUNTRIES JOINED LAST MONTH!
Countries number 192 and 193 just joined the listing of "Where in the World is antenneX?"
As is our custom, we welcome the latest newcomers and try to tell a little about the
countries, some of the history and any other things our research discovers that might be
of interest. The US CIA's World Factbook is most helpful in this research. A warm welcome
to these latest newcomers!
WELCOME AFGHANISTAN, COUNTRY #192
Background:
Afghanistan's recent history is a story of war and civil unrest. The Soviet Union invaded
in 1979, but was forced to withdraw 10 years later by anti-Communist mujahidin forces
supplied and trained by the US, Saudi Arabia, Pakistan, and others. The Communist regime
in Kabul fought on until collapsing in 1992. Fighting subsequently erupted among the
various mujahidin factions, giving rise to a state of warlordism that eventually spawned
the Taliban.
Backed by foreign sponsors, the Taliban developed as a political force and ultimately
seized power in 1996. The Taliban were able to capture most of the country, outside of
Northern Alliance strongholds primarily in the northeast. Following the 11 September 2001
terrorist attacks, a US, Allied, and Northern Alliance military action toppled the
Taliban.
In late 2001, major leaders from the Afghan opposition groups and diaspora met in Bonn,
Germany, and agreed on a plan for the formulation of a new government structure that
resulted in the inauguration of Hamid KARZAI as Chairman of the Afghan Interim Authority
(AIA) on 22 December 2001. The AIA held a nationwide Loya Jirga (Grand Assembly) in June
2002, and KARZAI was elected President by secret ballot of the Transitional Islamic State
of Afghanistan (TISA).
In December 2002, the TISA marked the one-year anniversary of the fall of the Taliban. The
Transitional Authority convened a Constitutional Loya Jirga from 14 December 2003 until 4
January 2004 and ended with the approval of a new constitution. The constitution was
signed on 16 January 2004 and highlights a strong executive branch, a moderate role for
Islam, and basic protections for human rights. TISA's next task is to hold nationwide
elections by June 2004, according to the Bonn Agreement timeline, but these may be delayed
due to election preparations.
National elections would formally dissolve the Transitional Authority and establish the
Government of Afghanistan under the new constitution. In addition to occasionally violent
political jockeying and ongoing military action to root out remaining terrorists and
Taliban elements, the country suffers from enormous poverty, a lack of skilled and
educated workers, a crumbling infrastructure, and widespread land mines.
The country has a population of just over 28 million with the median age of about 17.5 years, partially attributed to a life expectancy of 42 years for adults. Ethnic groups are Pashtun 42%, Tajik 27%, Hazara 9%, Uzbek 9%, Aimak 4%, Turkmen 3%, Baloch 2%, and others at 4%. Of the estimated 4 million refugees in October 2001, 2.3 million have returned.
Afghanistan remains extremely poor, landlocked, and highly dependent on foreign aid, farming, and trade with neighboring countries. It will probably take the remainder of the decade and continuing donor aid and attention to raise Afghanistan's living standards up from its current status among the lowest in the world. Much of the population continues to suffer from shortages of housing, clean water, electricity, medical care, and jobs, but the Afghan government and international donors remain committed to improving access to these basic necessities by prioritizing infrastructure development, education, housing development, jobs programs, and economic reform over the next year. Growing political stability and continued international commitment to Afghan reconstruction create an optimistic outlook for maintaining improvements to the Afghan economy in 2004. The replacement of the opium trade - which may account for one-third of GDP - is one of several potential spoilers for the economy over the long term.
Communications:
Telephones - main lines in use: 33,100 (2002)
Telephones - mobile cellular: 12,000 (2002)
Telephone system: general assessment: very limited telephone and telegraph service -
domestic: telephone service is improving with the establishment of two mobile phone
operators by 2003; telephone main lines remain weak with only .1 line per 10 people
international: country code - 93; satellite earth stations - 1 Intelsat (Indian Ocean)
linked only to Iran and 1 Intersputnik (Atlantic Ocean region); commercial satellite
telephone center in Ghazni
Radio broadcast stations:
AM 7 (6 are inactive; the active station is in Kabul), FM 1, short-wave 1 (broadcasts in
Pashtu, Afghan Persian (Dari), Urdu, and English) (1999)
Television broadcast stations: at least 10 (one government-run central television station
in Kabul and regional stations in nine of the 32 provinces; the regional stations operate
on a reduced schedule; also, in 1997, there was a station in Mazar-e Sharif reaching four
northern Afghanistan provinces) (1998)
Internet country code: .af
Internet users: 1,000 (2002)
Communications - note: in March 2003 'af' was established as Afghanistan's domain name; Internet access is growing through Internet cafes as well as public "telekiosks" in Kabul that are part of a nationwide network proposed by the Transitional Authority for Internet access (2002)
WELCOME BURMA, COUNTRY #193
Background:
Britain conquered Burma over a period of 62 years (1824-1886) and incorporated it into its
Indian Empire. Burma was administered as a province of India until 1937 when it became a
separate, self-governing colony; independence outside of the Commonwealth was attained in
1948. Gen. NE WIN dominated the government from 1962 to 1988, first as military ruler,
then as president, and later as political kingmaker. Despite multiparty elections in 1990
that resulted in the main opposition party - the National League for Democracy (NLD) -
winning a landslide victory, the ruling junta refused to hand over power. NLD leader and
Nobel Peace Prize recipient AUNG SAN SUU KYI, who was under house arrest from 1989 to 1995
and 2000 to 2002, was arrested in May 2003 and is currently under house arrest. Her
supporters are routinely harassed or jailed.
Location:
Southeastern Asia, bordering the Andaman Sea and the Bay of Bengal, between Bangladesh and
Thailand
Population:
42 million - Estimates for this country take into account the effects of excess mortality
due to AIDS; this can result in lower life expectancy, higher infant mortality and death
rates, lower population growth rates, and changes in the distribution of population by age
and sex than would otherwise be expected (July 2004 est.)
Age structure:
0-14 years: 27.6% (male 6,023,874; female 5,774,055)
15-64 years: 67.5% (male 14,317,308; female 14,504,500)
65 years and over: 4.9% (male 927,570; female 1,172,889) (2004 est.)
Median age:
total: 25.7 years
male: 25.2 years
female: 26.3 years (2004 est.)
Life expectancy at birth:
total population: 56.01 years
male: 54.22 years
female: 57.9 years (2004 est.)
Ethnic groups:
Burman 68%, Shan 9%, Karen 7%, Rakhine 4%, Chinese 3%, Indian 2%, Mon 2%, other 5%
Country name:
conventional long form: Union of Burma
conventional short form: Burma
local long form: Pyidaungzu Myanma Naingngandaw (translated by the US Government as Union
of Myanma and by the Burmese as Union of Myanmar)
local short form: Myanma Naingngandaw
Economy - overview:
Burma is a resource-rich country that suffers from government controls and abject rural
poverty. The military regime took steps in the early 1990s to liberalize the economy after
decades of failure under the "Burmese Way to Socialism", but those efforts have
since stalled. Burma has been unable to achieve monetary or fiscal stability, resulting in
an economy that suffers from serious macroeconomic imbalances - including a steep
inflation rate and an official exchange rate that overvalues the Burmese kyat by more than
100 times the market rate. In addition, most overseas development assistance ceased after
the junta suppressed the democracy movement in 1988 and subsequently ignored the results
of the 1990 election.
A crisis in the private banking sector in early 2003 followed by economic moves against
Burma by the United States, the European Union, and Japan - including a US ban on imports
from Burma and a Japanese freeze on new bilateral economic aid - further weakened the
Burmese economy. Burma is data poor, and official statistics are often dated and
inaccurate. Published estimates of Burma's foreign trade are greatly understated because
of the size of the black market and border trade - often estimated to be one to two times
the official economy. Better relations with foreign countries and relaxed controls at home
are needed to promote foreign investment, exports, and tourism.
In February 2003, a major banking crisis hit the country's 20 private banks, shutting them
down and disrupting the economy. In July and August 2003, the United States imposed a ban
on all Burmese imports and a ban on provision of financial services, hampering Burma's
ability to obtain foreign exchange. As of January 2004, the largest private banks remained
moribund, leaving the private sector with little formal access to credit outside of
government contracts.
Communications:
Telephones - main lines in use: 357,300 (2003)
Telephones - mobile cellular: 66,500 (2003)
Telephone system: general assessment: barely meets minimum requirements for local and
intercity service for business and government; international service is fair
international: country code - 95; satellite earth station - 1 Intelsat (Indian Ocean)
Radio broadcast stations:
AM 2, FM 3, short-wave 3 (1998)
Television broadcast stations: 2 (2003)
Internet country code: .mm
Internet hosts: 3 (2003)
Internet users: 28,000 (2003)
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.
If you haven’t already joined, you are invited and encouraged to do so. Just click here and follow the instructions on how to join and have fun with the rest of us. If you don't participate—it's a big opportunity lost!
==================================== |
AN INVITATION TO CONTRIBUTORS
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 submissions@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
This month is our 91st online issue online! We again include many fine articles by our great writing team. Now, allow me now to introduce this month's line-up of content:
THE NOVEMBER 2004 ONLINE ISSUE NO. 91 CONTENTS:
OUR MONTHLY COLUMNS (plus this one by yours truly):
Author, Werner says in his article: This Teslavert experiment emerged from Bill Miller´s idea about Transversal Currents presented in the September Issue of antenneX and my own previous Teslavert projects. I shall focus on the following 3 questionable experimental results:
1. Where does the radiation come from?
2. What is the resonant frequency of a Teslavert?
3. What is the Radiation resistance of a Teslavert?
FEATURE ARTICLES IN THE LIBRARY:
An
SWR-Feedline-Reactance Primer: |
| In this Part 1 primer, LB takes a look at a very common antenna: a 67' AWG #12 copper wire dipole for 7.15 MHz, that is, the center of the 40-meter band. He places the antenna at a height of 50' above average ground, which is ground with a conductivity of 0.005 S/m and a dielectric constant of 13. |
The
Tesla-Coil Dipole: A Spice Analysis |
| This month, Joel decided to exercise SPICE to learn what is going on in the center of the Tesla coil dipole. The drive circuit using a transformer used in last month's experiments is very sensitive to capacitance at the cable input. So, he decided to start over with a new driver circuit to connect the cable to the two Tesla coils. It was found this antenna to be very “aware” of its surroundings. It can be tuned to 400 kHz by bringing a hand near it. SPICE can fix the value of the components to 4 or 5 decimal points. Thus, it is possible to compute a perfectly tuned antenna, then change a parameter and see how the antenna behavior changes. |
Baluns
and the Complex Impedance Ratio |
| In a
previous articles, Joel included theory and some predicted measurement results of baluns
terminated in a complex impedance. These devices are usually described by many as a balun
(balanced to unbalanced) and use a balanced antenna tuner between it and the antenna
system transmission line source. In this instance, the transmission line is always a
balanced type with a fairly high line characteristic impedance, Zo, of 300 to 600 Ohms.
Since it is best to retain balance in hopes of experiencing balanced line currents, the
antenna tuner is thus required to be a balanced circuit. The tools used by Joel are the Autek Research VA1 vector RX antenna analyst and their WM 1 Computing SWR and power meter; the MFJ 259B HF/VHF SWR Analyzer; the Palomar Engineers PCM-1 RF Current Meter; and a Kenwood TS-870S Transceiver for a power source. These tools are not precise instruments but are “good enough” for determining comparisons between a balun TLT at the input or output of an impedance matching network. |
Trees
as Radiators |
| The idea
of using trees as radiators started from a very different point of view. I was reading an
article in antenneX on the ILA (Ionic Liquid Antenna), now in the antenneX
Archives. The idea was to use an ionic saline solution to build antennas, instead of
wires. I started to build a ground plane in my Lab, using for the upper element a PVC tube
filled with a saturated saline solution. This experiment showed me that a saline ionic
solution was not such a bad radiator as I could think at first glance. A PVC pipe filled
with saline solution is not so easy to manage as a metallic pipe, and surely heavier.
While I was thinking that some practical application of the principle was quite difficult,
suddenly appeared in my mind the analogy with something very well known, tall and already
built…..a tree! The idea was to use a tree as radiator using the part outside the ground as a pole with a capacitive hat and the part inside the ground (the roots) as a ground plane. To test if this was only a crazy idea or something possible, I thought to use a gamma match configuration to measure the impedance of one of the tall trees I have in my garden (around 10 m). |
An
Experiment on Power transmission & the Poynting Vector |
| Recently, readers of antenneX magazine who subscribe to the Antenna Discussion list have been exposed to the idea that, in a dipole antenna, the power conveyed by the electric and magnetic fields, which can be summarized by the Poynting Vector S = ExH, travels parallel to the rods of the antenna, rather than directly outwards from it, as some people's common sense would suggest. Find out why David thinks so in this article. |
Some
Thoughts on Maxwell’s Equations & Radiation |
| Over the years, and more recently in antenneX forums and articles, antenna practitioners and even some academicians have questioned the “real life” validity of Maxwell’s version of Ampere’s law. This is the equation that contains “displacement current.” In this article, we shall examine this derivation. From this we shall revisit the fact that the derivation is brilliant, insightful, precise, and led mankind on the path to radio, television, cell phones, radio astronomy and a host of other wonders. We know that Maxwell’s derivation was based on the scientific knowledge of the nineteenth century. Twenty-first century science now reveals that two key assumptions were incorrect, according to Bill. As a result, the derivation has pointed electromagnetic theory in a slightly skewed direction. |
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. November
2004 antenneX Online Issue #91
reGARDS, Jack L. Stone, Publisher jack@antennex.com
Send mail to webmaster@antennex.com
with questions or comments.
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Last modified:
December 31, 2010
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