Adjusting Near-Perfect Broadband Antennas for 80-75 Meters
By L. B. Cebik, W4RNL (SK)

In “Notes on Ribbons, Cages, Parasites, and Lines: Broadband Coverage of the 80-75-Meter Band with AWG #12 Copper Wire” in a past issue of antenneX, I explored some of the methods for obtaining full coverage across the 3.5 to 4.0 MHz span with a single antenna. I re-examined some further options in a QEX column (“Antenna Options”) that opened some additional possibilities offered by combining broadbanding techniques. Some of the methods of matching via combinations of transmission line proved robust enough to allow the use of ribbon or cage constructs with relative small proportions, instead of the very large dimensions required for direct full coverage by the antenna alone. In fact, we were able to obtain 50-Ω SWR curves with values less the 1.5:1, thus meeting the most rigorous requirements of amateur amplifiers having the most sensitive fold-back circuits.

Near the end of the QEX piece, I cautioned that the dimensions shown in the samples applied only to antennas in the 70’ to 100’ height range over average ground. Outside that range, the antenna builder will have to make a considerable number of experimental adjustments to assure performance, and at some heights, the arrangement may not work at all.

Practical Antennas: Part 2.6
By Marcel H. De Canck, ON5AU

The ionosphere plays a tricky but an important role to our radio communications, and there is very little we can do about it. But there is plenty you can do about having a good and efficient antenna system. Yes, antenna system, it’s not the antenna itself but the whole part as transmission line, and matching properly the transceiver and the antenna to the transmission line. It is a breath-taking concept that a simple length of wire or rod or tube can transform electrical energy into invisible radio electro-magnetic waves that can cross the space at the speed of light.

How does an antenna system works? Why does the antenna radiate electro-magnetic waves? These questions I heard many times and the answers are not given with few words. Never-the-less, many books and some of great weight and complexity have been written about antennas and many antenna types have been developed and build. Often it is not comprehensive to the layman to fully understand the whys and hows of the radiation capabilities of an antenna and these counts even for the simplest ones like a dipole or a groundplane. Also I often hear many times misconceptions about antenna properties and characteristics. To start with, understanding why and how a simple antenna effective radiates will be explained in a clear view. The dipole is the best antenna to do that and once the secrets of the dipole characteristics and properties are fully understood it will be much easier to have a clear insight of the hows and whys of more complicated antennas.

The first episodes will handle completely about antenna fundamentals mostly with the half wavelength dipole as study example. The dipole is also often a part element of more complicated antennas such as a Yagi and others. In particular for the low frequency bands, the dipole is used by many radio amateurs as transmitting or receiving antenna and its many practical installations and shapes will be fully studied and explained in a chapter later on. In fact many other antenna types will become subject to explanation as the antenna story develops.

NewcomerNotes: Working Close to Home
By Robert Gulley, AK3Q

A Dual-band Yagi to cover both 28MHz and 50MHz
By Justin Johnson, G0KSC

Within this article we will look at the design and construction of a dual-band Yagi which will provide good coverage of at least the CW/SSB portions of both the 28MHz and 50MHz bands. This antenna has been designed with ‘easy to build’ in mind and the requirement for all parts to be freely available. Additionally, a small tool shed should be all that is required to get this antenna completed and in the air by first time or experienced antenna builder.

The multi-band antenna is a compromise antenna and one born from the ‘real-world’ requirements of the modern ham. Namely the requirement to consolidate the number of antennas installed at our ham station, the reasons for which are many. However, while the differences between a full-size dipole and multi-band dipole are relatively small, the differences in performance between a full size, computer optimized Mono-band Yagi and a multiband Yagi of the same of similar length are a long way apart, but why is this?

The New P-pole Antenna
By Edward J. Shortridge, W4JOQ

A completely new antenna is being presented which has many highly desirable characteristics, such as extremely low SWR, over a 3.12/1 bandwidth, covering all frequencies between 144 and 450 MHz. The Far-field RF gain is very uniform throughout the range and it has low angles of radiation across the entire bandwidth. There are few if any antennas that can match its performance.

The antenna consists of six half-wave straight vertical radiators arranged in a circular pattern, surrounding the mast, with each radiator fed separately, and then combined for a 50-Ohm source.

Pillbox Antenna for 5.6 GHz Band
By Dragoslav Dobričić, YU1AW (Serbia)