Newsletter 5.0

Antenna Magus version 5.0 released!

As we continually strive to make Antenna Magus a more powerful and inclusive design tool, we are pleased to announce the fifth major release of Antenna Magus. Version 5.0 incorporates a large number of improvements and new features as well as extensions and updates to the Antenna Database - the addition of 25 new antennas takes the total number to 250!

In this newsletter we will introduce some of the new features and briefly look at the new antennas.

New Features

Smart Design

“Design at the click of a button, using the information you have” is the essence of Smart Design. The multi-step design process used in earlier versions of Antenna Magus has been simplified down to just one click.

While it is still possible for the user to specify all design objectives, Smart Design caters for empty or incomplete objective sets (A). Antenna Magus uses all objectives which have been specified to intelligently predict suitable input values for unspecified objectives required for design. The suggested values determined by Antenna Magus may subsequently be adjusted by the user to refine the design.

In order to make Smart Design even more powerful, objectives are grouped according to type. For each of these groupings, a type-specific calculator (B) is provided. The calculators allow the user to convert different representations of each data grouping into the required input objective(s) without having to perform conversions outside of Antenna Magus. Smart Design allows the user to specify what he knows and confidently rely on Antenna Magus to do the rest by simply clicking the Design button (C).

Getting a good design has never been easier!

Design Mode Palette, showing some of the Smart Design tools

Chart Tracer Tool with value extraction

The Chart Tracer Tool has been expanded with the addition of quick representative value extraction capabilities. Once a trace has been captured and the X and Y axis types specified, the tool automatically calculates relevant performance parameters.

In this way, useful values e.g. bandwidth, beamwidth, minimum, maximum etc. can be determined quickly from plots or images and used in the Specifications Library, for Design or elsewhere.

The expanded Chart Tracer tool, showing axis type selection and automated representative value extraction

Specification Library

The Specification Library may be used to store various design specifications in a structured format. These Specifications may subsequently be used in Find Mode (to help identify feasible antennas) as well as in Design Mode (to populate the Design Objectives of antennas in the Collection). A number of pre-defined specifications are included as part of the library. These pre-defined Specifications may be used as-is or expanded and refined by the user.

Each Specification contains Values representing the performance requirements of the targeted design, as well as Keywords describing the required antenna. Specifications may be defined and refined using a number of tools provided in the Specification Editor interface. These tools include the Antenna Magus Keyword dictionary, the Conversion calculators (also available in the Design Mode) and the advanced Chart Tracer tool (described in the previous section).

Some of the Specification capture tools provided in the Substrates Library including: Embedded Chart Tracer; Type-specific conversion calculators; Keyword selection; Use Specification for Find/Design

By using the Specification Library, information about your design goals can be captured and refined before any specific antenna/s have been identified. It is also possible to capture and store a lot more information about your design requirements and to use/reuse this information while designing different antennas. Specifications that have been defined and refined are included in the Antenna Magus backup and are easily accessible for later use or for sharing with other Antenna Magus users.

General improvements

Many improvements have been made to the Antenna Magus workspace and workflow to make antenna design and learning easier. Once again, we will only highlight a few of the exciting ones.

Start Page

A new Start Page, shown each time that Antenna Magus is launched, provides quick access to a number of Help documents and recently used items. This page also contains links to the typical starting points for the various workflows within Antenna Magus.

Image and Data Export

In the Antenna Magus workspace, all images and information items may be exported to images or text on the clipboard or to a file. This includes all charts of Estimated Performance data as well as antenna images, sketches and Palette data.

Zoom to sub-windows

In order to make it easier to observe details within sub-windows of the Workspace, sub-windows may now also be switched to Zoomed view, in which the selected view fills the entire workspace area.

Grouped Information Document Index

The Information Browser has been expanded to include a listing of all Information Documents in Antenna Magus, grouped by family. This makes it easy to find a specific document to read or compare.

Auto Update

Version 5.0 introduces an Automatic Update mechanism that can be used to check whether updates are available. The changes that are included in the update can be browsed before downloading and installing at the click of a button. Only updates that are available according to the M&S expiry date are downloaded.

More than 250 antennas

25 new antennas are included in Version 5.0

Array antennas

A number of useful arrays have been added. These include a relatively simple dipole panel array, a multi-sector patch array often used as part of mobile base-stations and finally, an extremely versatile M-by-N rectangular patch array with corporate feed.

The M-by-N patch array is a more versatile implementation of the linear and planar microstrip patch arrays currently contained in Antenna Magus. There are M patches on the X-axis and N on the Y-axis, where M and N are both powers of 2 (result of exponentiation with as base the number two and as exponent the integer n).

The available export models of the M-by-N patch array are parametric for an M by N array where M and N are powers of 2 for the range 2 to 8. An additional export model containing only the parametric corporate feed network – to which any radiating patch element may be added after export – is also available.

3 new array antennas, with typical performance for an M-by-N patch array design shown

Waveguide and reflector antennas / devices

The transitions already available in Antenna Magus have been expanded through the addition of a high power coax to waveguide transition. This transition employs a ‘T-bar’ type transition to prevent arcing, while maintaining good bandwidth.

Three practical reflector-type antennas have been added. The Parabolic reflector with double-dipole splashplate feed, for example, uses the backfire radiation of the feed structure to illuminate the dish. A waveguide section that passes through the centre of the reflector provides support of the feed structure at the focus point. This approach allows excitation of the antenna without introducing additional aperture-blockage, as all feed electronics can be placed behind the reflector.

The double-dipole feed (supported by the waveguide termination section) comprises two dipoles mounted so that their axes lie on the plane of symmetry of the guide. Through proper spacing and dimensioning of the dipoles, the coupling may be controlled to produce a feed pattern with a 10 dB beamwidth in the region of 180 degrees to illuminate the parabolic reflector. Though the radiation pattern of the feed cannot be modified much, the overall radiation pattern of the antenna can be adjusted by adjusting the size or shape of the reflector and by modifying the feed placement.

3 new reflector antennas and one coax-to-waveguide transition. The performance of a typical double-dipole fed parabolice reflector is shown.

Wire Antennas

The wire antennas introduced in Version 5.0 are all variations of the simple dipole antenna. The J-pole antenna has been a popular communications antenna for many years, and was used on the Zeppelin dirigibles in the 1930’s (hence it is sometimes referred to as an ‘end-fed Zepp’). The gain of the basic J-pole may be increased by adding an additional radiating section, resulting in the longer Super J-pole structure.

Wheel antennas are a group of antennas consisting of a number of loops rotated equally around a feed point. The horizontally-polarised ‘Big Wheel’ consists of 3 loops which are all orientated parallel to the horizon. Omnidirectional circular polarisation can be achieved by twisting the elements to a 45° angle to the horizon. The most popular configurations are the 3 element, better known as the ‘Clover leaf antenna’, and the 4 element, better known as the ‘Skew planar wheel’. The Clover leaf and Skew planar wheel are very popular among FPV (First Person View) enthusiasts.

The half wave arcs can be seen as half wave dipoles circularly spaced around a centre point, thus creating a circular array of dipoles.

4 new wire antennas added to Antenna Magus. Typical performance of a Wire Wheel is shown.

Planar antennas

A handful of planar antennas have been added, ranging from a wideband microstrip-fed linear tapered slot to an ultra-small integrated monopole for integrated WLAN applications. A dual-band PIFA antenna finds many applications in mobile communications, such as GSM 900/1800. The parasitic element provides additional bandwidth when compared to other multi-band PIFA’s available in Antenna Magus.

The cavity-backed annular slot antenna is often used in airplane applications, as it can be flush-mounted so that it has little impact on the aerodynamic performance of the platform. The particular structure in question has an air-filled cavity backing (designed to support the dominant TE010 mode), while a shorting strip (bridging the slot separating the central disc and remaining ground plane) can increase the impedance bandwidth of the structure to beyond 10%.

5 new planar antennas have been added. Typical performance of the cavity-backed annular slot is shown

Polyrod and horn antennas

A number of leaky wave dielectric rod antennas, as well as a spiral phase plate (used with a Potter horn to create a difference pattern) have been added to Antenna Magus.

While a wide range of configurations are possible for dielectric-rod antennas, in most cases they have a tapered rod of circular or rectangular cross section. In these antennas, the feeding waveguide couples part of the input power into a surface wave which travels along the dielectric rod with minimal reflection. The surface wave then continuously radiates as it travels along, gradually transforming from a strongly bounded wave to a free-space wave.

Reduced side lobe levels are attainable through proper design, however this also results in reduced gain. By adding a horn launcher (or a short flared section at the waveguide termination) side lobe reduction with little impact on gain is possible, as shown in the figure to the right.

The impact of a horn-launcher on the radiation pattern of the rectangular tapered rod antenna is shown

Wideband planar antennas

A number of practical wideband planar spiral antennas with absorber-lined cavity backings have been added. Layers of absorbing material are added to a metal cavity in order to obtain unidirectional radiation, while still maintaining multi-octave bandwidth operation of the spiral elements.

The cavity-backed 4-arm Archimedes spiral, for example, is a versatile structure able to operate in sum and difference mode. Mode 1 operation of the basic spiral structure produces a boresight maximum by utilising a 90 degree progressive phase shift between ports, while mode 2 operation produces a boresight null using a 180 degree phase progression. The effect of the cavity-backing may be illustrated by considering an antenna designed for left-hand circular operation in the forward direction, and investigating the opposite polarisation. While the spiral without a cavity backing produces a backward beam equal in magnitude, but opposite in polarisation to the forward beam; the absorber-lined cavity model does not - as shown at the centre frequency in the figure below.

Though the feeding mechanism required for a four-arm spiral may be quite intricate, it remains an extremely versatile antenna that has been used extensively for broadband, multi-octave, direction-finding applications, such as satellite tracking systems and missile antennas for homing on radio frequency transmitters.

4 wideband spiral antennas with absorber-filled cavity backings have been added. The impact of the absorber-filled cavity on cross-polarised radiation when compared with a free-space spiral is shown.