Type S Series-Section Broad-Banded Antennas
by Edward J. Shortridge, W4JOQ

WHAT IS THIS?
simple antenna modeling method is presented, which is capable of increasing the bandwidth of most antennas to about three times without altering the basic design.  It is not intrusive on the antenna itself or its radiation characteristics.  It does not add anything physically to the antenna.  All of the broad banding is accomplished in the transmission line. It is called the “Type S Series-section Broad-Banding method.”

It also uses modified versions of series-section matching transformers and ¼ & ½ wavelength transmission line transformers to enhance the Type S Method.  In this presentation, a very large number of possible bandwidth variations are shown including multi-band antennas. Most of the variations are quite simple to achieve but many of these do not use practical transmission line impedance or line lengths, but many do. In the HF frequency range, a “Transformer-Enhanced” broad-banding variation was developed to allow the use of more realistic coaxial line impedances and lengths. It can show us what is possible and practical applications will surely follow. Anyone seriously involved in antenna modeling needs to understand this very useful tool.

        Two chapters of the book cover 75/80 Meters. Horizontal and inverted-V antennas that are broad-banded by the Type S Transformer-Enhanced and Coupled-Radiator methods. There are many practical illustrations in this 134-page book.      

In the preliminary illustrations of this book, only lossless transmission lines were used. This did not represent a realistic view of the broad-banding methods. Then, the newer EZNEC Pro/2 v. 5.0 antenna modeling program became available. It permits an easy method of specifying transmission line losses at specific frequencies, as listed in various publications such as the ARRL Antenna Book. The program translates the correct losses into the lines at frequencies used in the antenna being modeled. This gives greater validity to the broad-banding results. Therefore, all antenna models in this book contain realistic transmission line losses. In most cases, the added line losses are moderate and they give some minor improvement to the SWR within the bandpass.

Every effort has been made throughout the antenna models presented to make certain that all of the rules governing the modeling program’s accuracy are observed. Most of the antennas presented are relatively simple radiating elements which become relatively easy to ensure this program’s accuracy.

Click here for an Introduction Article

THE AUTHOR
Edward J. Shortridge, W4JOQ has been a licensed amateur for 70+ years. Ed began his interest in radio and electronics at the early age of 14, when the VHF/UHF state-of-the-art was super-regenerative tube detectors, Long-Line oscillator transmitters, using #45 or #10 tubes. The only choice of frequency measuring devices at that time was Lecher Wires. He became a licensed Amateur radio operator at 18 years of age.

He joined the Naval reserves as a radioman in order to save money for college. After radio school, he was assigned to the Key West naval base.  He had duty in the radio laboratory, radio receiving room, and was in charge of the main transmitter room.

Ed met his wife Marilyn while stationed at the Key West Naval base (NAR) and they were happily married together for only a short period of time before a national emergency was declared and he was soon shipped overseas during World War II. He had to remain in the U.S. Navy for a total of five years. He was chief radioman for two years as part of Admiral Hall’s staff of the “5th Amphibious Force” and participated in invasions of Algeria, Italy (Salerno), Normandy (Omaha Beach), Philippine Islands and Okinawa. After returning to civilian life he fathered two children and worked at the following companies in Miami, Florida:

• Communications Company- Chief engineer-22 years

• Microtenna-Chief engineer-2  years

• Wackenhut Electronics-Chief engineer-3 years

• Shakespeare Marine Electronics-Chief Engineer - 7 years

• Hallicrafters-Director of  radio engineering-3 years

• Aerocom-Chief engineer-7 years

Profession was directly involved in the design and development of:

• First VHF/UHF land mobile radio and repeaters

• Balloon-mounted VHF/UHF repeaters for Vietnam war

• Moon Landing VHF radio communication simulation

• Ground base to  satellite communications

• HF and VHF Marine radio

• Marine depth finding equipment

• US military radio equipment

• Antenna design and manufacturing

Constant study, correspondence and seminar courses, along with professional engineering study groups, provided him with a background for continued electronic knowledge enhancement. His antenna design experience at several of these companies propelled his interest and experience in antenna design.

He retired in 1990, built a very nice retirement home. But in 1992, one third of it was destroyed by Hurricane Andrew, with all the ham radio, very good test equipment and the entire engineering library. In 1999, Ed bought a 116 acre mountain cove in western North Carolina and built another home.

Being in a mountain cove, there were concerns about what type of antenna could be used to get signals out of the cove, so the purchase of an EZNEC antenna modeling program helped. Over his engineering career, he designed many types of antennas, but had to do it the hard way without the new technological tools that emerged. There were many ideas over the years, but they had been too difficult, and time-consuming to pursue.

With the new modeling program, it became much easier to come up with designs. Several basic ideas that seemed a standout were worked on. They worked out quite well and were expanded into a large variety of antennas. First it was wideband antennas, but another basic idea was adaptable to widening most narrow-band antennas.

So far, Ed has spent 9 years of constant full-time effort on antenna designs, and is very excited about many ideas and concepts. There is not enough time in the day to satisfy his curiosity.

THE BOOK CONTENT

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