portable-antennas

portable antennas

Welcome to portable-antennas.com! This site aims to provide the radio amateur with easy-to use tools enabling design and modelling of simple wire antennas for the HF bands, primarily for amateur radio portable use, such as for activations of parks, hills and mountains, islands and lighthouses in the various amateur radio outdoor award schemes. Like all such antennas, they can also be used at a home QTH.

The tools included in each designer page enable displays of radiation patterns, VSWR curves, antenna current diagrams, and Smith charts - all calculated and displayed dynamically for the antenna you design. No other website offers such an extensive set of tools to check your antenna design.

Example azimuth radiation pattern

Example elevation radiation pattern

Power to the user

The designer pages in this site use the powerful industry-standard NEC engine in the background to dynamically calculate data describing the performance of the antenna you have designed. These data are then parsed, analyzed and displayed in the formats you have chosen. Up until recently, we had been using an older NEC v2 engine in the background, but we have now updated all of the designers to use a more up-to-date and more capable NEC v4.2 engine.

Of course, other NEC-based antenna modelling and design tools and programs do exist: for instance: EZNEC Pro, 4Nec2, MMANA-GAL ^* and others, but all of them need to be installed on your PC or Mac/Linux machine. These programs are certainly very powerful, and generally give very good results - the downside is that such programs are often very complex, and involve a steep learning curve in order to become proficient in even the simplest of tasks. Not everyone has the desire to spend so much time and effort in gaining the skills and knowledge required by such programs to model even the simplest kind of antenna.

^* We accept no liability for the content of external links - use them at your discretion.

Easy to use

The tools provided in this site take much of the complexity out from the task of modelling and designing of simple wire antennas. Parameters such as frequency, wire lengths and angles are easily input, and results presented in interactive 3D graphical form at the click of a button.

This is achieved by having each of the designer pages in this site focus on one particular type of antenna, with custom code and options to match, making it much easier for the user to concentrate just on the antenna of their choice. This is quite unlike the approach taken by the programs mentioned earlier because, since they are designed to cater for any and all conceivable antenna types, the large number and scope of options they need to include can quickly become confusing or bewildering.

Example 3D antenna display

Experiment!

Users of the antenna designer pages in this site are encouraged to experiment with the antenna designer of their choice, to try different values of frequency, antenna section lengths or angles, height of antenna above the ground, to try out different ground types, and so on. Spend some time to see what effects these changes will have on the antenna's radiation patterns, or on the VSWR, or how currents are distributed in the antenna, as the changes are made. In this way, you will learn a great deal more about your choice of antenna in particular, and also about antennas in general, than just trying one set of values.

Different antenna types

Currently, the following antenna types for the HF bands can be modelled, with more being considered for inclusion:

Linked dipole antennas - for single or multiple HF bands;
Off-center-fed dipole (OCFD) antennas - capable of giving good results (low VSWR) on several bands above the principal band;
End-fed half-wave (EFHW) antennas - capable of giving good results (low VSWR) on several bands above the principal band;
Vertical antennas - for one single band, with all-round, low-angle radiation;
Delta loop antennas - for one single band, providing vertically-polarized emissions at low elevation angles - a good DX antenna.
Half-square antennas - can be configured either as a full-wave single-bander, or as an EFHW multi-bander.
Moxon antennas - for one single-band, a compact two-element beam antenna with good gain and very good F/B ratio.

Radiation patterns, polarization patterns, VSWR charts, antenna currents diagrams and Smith charts

For each of the antenna types currently supported, any combinations of the following charts and diagrams can be generated and displayed:

azimuth and elevation radiation patterns;
3D radiation patterns;
NEW azimuthal polarization patterns, showing both horizontal and vertical components of the polarization pattern, as well as their sum;
VSWR curves, incorporating real and imaginary impedance curves - VSWR curves are displayed for
either one single band, or over several bands;
antenna currents diagrams, showing how currents are distributed in the antenna;
Smith charts, showing how antenna reactance changes with frequency.

Example VSWR+impedance curves covering several HF bands

Export results

Results from the design and modelling can be exported in either PDF, CSV or simple text formats. In addition, antenna dimensions suitable for importing into a professional program can also be exported.

Extras page

In addition to the designers, the site also offers the

Extras page - featuring data-sets and charts for various coaxial cable types, reference correction factors, and calculators.

About page

The site also offers the

About page - which gives an overview of the main pages in the site, and includes descriptions of the antenna design pages, with some
introductory information on each antenna type and its' characteristics.

A Note On Length Units

We use meters as length units exclusively and unapologetically throughout this site, since the metric system has been adopted by almost all major industrialized countries in the world. With just one exception - the United States of America, which still uses the cumbersome and outdated Imperial system of measurements which include feet, inches, yards and miles.

Early attempts to include the Imperial system into the calculations and display of both metric and Imperial values in this site indicated very clearly that the additional effort required was just too much, and greatly hindered the further development of the site. With this in mind, and also noting that the entire US population represents less than 4.5% of the world's population, we decided not to support Imperial measurements, and to go forward with metric, the gold standard used by over 95% of the world's population.

Indeed, many US amateurs themselves have decided not to continue to use the Imperial system when designing and building antennas. See e.g. this Youtube video from Toivo W8TJM, where he explains how he has converted completely to metric, "because it's a lot easier to do antenna calculations metrically, rather than trying to convert inches and feet ... none of that conversion's necessary if you go metric."

We have, however, included a metric/Imperial conversion calculator in the Extras page for those users who may still, in this day and age, be unfamiliar with - or do not yet use - the metric system.

Footnote

Please be aware that this site is a work in progress, with updates occurring on almost a daily basis. From time to time, some functions may not appear to work, or may not work correctly. This simply means that those functions are in the process of being updated or changed. If it doesn't work now, check back later!

If any problems with the site should persist, please use the Contact form to let us know!