Archive for the ‘Uncategorized’ Category

Antenna Magus 2018.0 Released!

Wednesday, December 13th, 2017

We are pleased to announce the release of Antenna Magus Version 2018.0 which sees a number of new features and improvements, as well as two new antennas.

Some of the highlights of this release are:

  • Over 325 antennas and transitions now available
  • Spatial Limitations can now be added as part of a specification. Antenna Magus will  determine whether the designed device will fit into the available space and which orientation will achieve the closest fit. The spatial limitations are graphically shown together with the bounding box of the device in order to visualise whether the device fits within the limits or not
  • Trace Names for 2D Radiation plots have been standardized to be in terms of ? and ?, in accordance with the Spherical Coordinate System and will simplify comparison of different devices in the Compare Window.
  • To aid the user in using Toolbox Calculators, the objective fields in all Toolbox Calculators are now pre-populated with default values.
  • In addition to the recently added zoom function in the model preview, it is now also possible to pan the preview model.
  • A planar triangular array has been added to the Array Calculator.

For more information on this release, please visit the Antenna Magus Website or read the Version 2018.0 Newsletter.

Triangular array layout

Length, area and volume limitations

Two new horn antennas

Antenna Magus 2017 released

Tuesday, March 14th, 2017

We are pleased to announce the release of Antenna Magus Version 2017! This is a major product update that includes new features as well as improved workflow and options.

Some of the highlights of this release are:

  • Over 315 antennas and transitions now available
  • Antenna Magus now exclusively available in native 64-bit architecture
  • For licensed users of CST STUDIO SUITE® it is now possible to license Antenna Magus using the CST License Manager.
  • The relative spacing and distance between array elements may now also be specified in physical distances (e.g. meters or inches)
  • Improvements to the current Specification based workflow.
  • Various performance improvements have been made, impacting specifically on Find Mode and responsiveness when switching between Designs and Prototypes.
  • The Performance Estimation of many antennas have been accelerated and additional Designs and Tweaking options added.

For more information on this release, please visit the Antenna Magus Website or read the Version 2017 Newsletter.

Antenna Magus Version 5.5 Released

Wednesday, October 7th, 2015

We are pleased to announce the new release of Antenna Magus Version 5.5! In addition to some small feature extensions, this release includes new antenna designs and some exciting new transitions – which are extremely useful when designing feed structures and networks for antennas.

The new transitions are:

  1. Microstrip-to-waveguide transition
  2. Microstrip quadrature-hybrid coupler
  3. Microstrip ‘rat race’ coupler
  4. Broadband microstrip radial stub (band-stop structure)
  5. Coax-to-circular waveguide transition
  6. Coax-to-microstrip line transition
  7. Broadband coax-to-quad-ridged waveguide transition
  8. Coax-to-coplanar waveguide (CPW) transition

and the new antennas are:

  1. Quad-ridged conical horn antenna (QRFH)
  2. Pyramidal horn antenna with spherical Luneburg lens
  3. Pyramidal horn antenna with cylindrical Luneburg lens
  4. 2-by-2 array of sequentially rotated wire helix antennas
  5. Planar elliptical dipole antenna

For more information on this update, please visit the Antenna Magus Website or read the Version 5.5 Newsletter.

Cylindrical Luneberg lens

A 6-layer cylindrical Luneberg lens (cut-away to show layering) with pyramidal horn excitation and 3D radiation pattern.

Folded Dipole – bent and twisted…

Wednesday, October 7th, 2015

Antenna Magus simplifies the task of choosing a suitable antenna. Of course if you simply need a structure that will radiate at a certain frequency – without a specific pattern or impedance requirement – the task is a lot simpler!

I have seen a number of articles and papers where the possibility of using logos as antennas is considered – most notably Apple in the iPhone and Macbook following the 2010 “Antennagate”  scandal. Designing a ‘logo-antenna’ seems quite straight-forward:

1.  Figure out how big the structure should be
2.  Figure out how to excite the structure

… and then see if it radiates efficiently.

How do you go about doing this for a general logo though? If you can start from a well-known antenna that has a similar structure or shape to the logo then (even without extensive EM and antenna knowledge) the principles and guidelines of  the known radiating structure can probably be used as a good starting point to determine how to achieve some form of semi-efficient radiation for the logo.

btfd_3D

To illustrate, we have done a simple investigation using the official Magus logo. The “known” Folded dipole antenna can be morphed into a structure resembling the Antenna Magus logo… essentially a bent and twisted folded dipole. Starting from the Folded dipole designed at 1 GHz (courtesy of Antenna Magus) the “logo-antenna” above was designed.

btfd_s11

And how does this “logo-antenna” perform… quite well! At the 1 GHz centre frequency, the reflection and radiation performance is comparable to the original Folded dipole, with a 14% (-10 dB) reflection bandwidth and a gain of 2.3 dBi at the centre frequency. Nice!

And what about other well known logos?

Some are easy:

While some of the best known logos such as Nike, Coca-Cola and Ford are not that easy to match up… any ideas?

So how well does my antenna have to be matched?

Friday, October 26th, 2012
Friis equation illustration

Friis equation illustration

Friis equation

Friis equation

I recently had some trouble matching an integrated antenna over the whole operating band, while sticking to the available space for mounting on a PCB? so? I got to wondering things like: ?what is the actual effect of return loss and gain on the communications range??

After spending some time musing about the Friis equation (above) – with the help of the Friis tool in Antenna Magus – I rediscovered why some general guidelines like ?- 10 dB is a good enough match and stick to lower frequencies for long distance communications?, are worth following.

I picked the following typical values:

Gt = Gr = 10 dBi, |S11|t = |S11|r = -20 dB, Pt = 1 W, Pr = 10 pW and Freq = 900 MHz.

and considered the effect of varying frequency, gain and |S11|t within this typical system. Note that the black marker on each graph represents the above-mentioned typical design case.

Relationship between return loss (|S11|)  and range (R)

Relationship between return loss (|S11|) and range (R)

The above graph clearly shows why threshold for acceptable return loss is -10 dB. At -20 dB there is less than 2% reduction in range, at -10 dB and -6 dB the range is reduced to 5.5% and 14.5% respectively. In communication systems where maximal range is not such a strict specification 85.5% of the theoretical maximum range does seem like a reasonable trade-off, but if you can, it is definitely worth the effort to try get the extra meters!

Relationship between gain and range.

Relationship between gain and range.

Next I plotted the relationship between antenna gain and range. The plot illustrates the communication engineers mantra: “for every 6 dBi increase in antenna gain, the range will double” – therefore range will increase from 80 km to over 2600 km when increasing the gain from 5 dBi to 40 dBi (equivalent to replacing a patch antenna with a large, high gain reflector antenna while changing nothing else in the system).

Relationship between frequency and range.

Relationship between frequency and range.

What about frequency? If we ignore all the pitfalls of propagation absorption and environmental effects, Frequency and Range are indirectly proportional to each other ? so doubling the frequency will halve the range. If one plots this relationship (as shown above) it is clear why long distance communication systems typically operate at lower frequencies.

So what did I learn from this exercise that helped me make some design choices?

  1. I could increase my operating frequency so that I can use an electrically larger antenna that is easier to match. If, however, I need to increase the operating frequency by anything more than 10% to help me improve my reflection coefficient from -6 dB to -10 dB, the net result will be a reduction in range.
  2. If I can design an antenna with similar size (and similar impedance), but with increased gain in the direction of interest, then I can achieve the same effect as improving the matching. The additional gain required in this instance is around 0.8 dB. For a low gain antenna like mine (with around 3 dBi gain) getting an additional 0.8 dB might be a challenge in the space I have. In another situation, optimising a higher gain antenna, like a 12 dBi horn – to get an extra 0.8 dB sounds a lot more doable.

I hope this exercise helped you (as it did me) put the different factors in a communication system in perspective.

Author: Robert Kellerman

Version 4.1 released

Wednesday, September 19th, 2012

We are pleased to announce a new release of Antenna Magus – Version 4.1. This release sees the addition of 15 new tools, expanding the toolbox to 24 tools and calculators to assist antenna designers with every day antenna-related tasks. Tools include a chart-tracing tool used to convert trace data to numerical values, a two-port network parameter conversion tool, an RCS calculator, and a decibel (dB) to linear power ratio converter, among others.

For those who were not aware of this fact previously, Antenna Magus broke the 200 antenna barrier with the previous release and now boasts 204 antennas – the largest commercially available database of antenna designs in the world.

The Version 4.1 database is expanded through the addition of four exciting new antennas: the Axial choke horn with a dielectric lens, the Offset-fed Gregorian and Cassegrain reflectors and the ?Eggbeater? antenna.

Read more about the added features and?extensions?in newsletter 4.1

Preview of newsletter 4.1

Preview of newsletter 4.1

Author: Robert Kellerman

Antenna Magus 3.1 released

Wednesday, July 6th, 2011

We recently launched Antenna Magus 3.1. This update features 6 new antennas and 2 new transitions. More useful additions are: 3D gain patterns were added as part of the performance estimation, info docs now include summarising thumbnails which indicate the electrical size and typical radiation pattern of each antenna and the array synthesis tool undergone some major UI improvements. Read more in the latest newsletter 3.1

Preview of newsletter 3.1

Preview of newsletter 3.1

Author: Robert Kellerman

Why 50 ohm?

Wednesday, November 10th, 2010

A couple of our engineers recently had a long discussion while trying to decide what range of impedances to include for the design of a coaxial feed for one of our antennas. The question that quickly arose was: ??why are most coaxial cables that are commonly available 50 ohm or 75 ohm??. I?m sure you must have asked yourself the same question before.

While looking into this, we discovered a 1955 IEE paper, titled ?THE CHOICE OF IMPEDANCE FOR COAXIAL RADIO-FREQUENCY CABLES? by WT Blackband. It is an excellent study considering various factors like attenuation, voltage, cable thickness and thermal characteristics of coaxial cables of various impedances and made with various materials. Though each performance measure for coaxial cables suggests a different optimal impedance, the general conclusion is basically: ??The best choice of impedance is 75 ohms for low-loss air-spaced cables, and 50 ohms for general-purpose thermoplastic cables.?

A definite must read if you ever wondered what the best coaxial cable impedance might be for a specific application ? and why 50 Ohms and 75 Ohms seem to be so popular!

Author: Robert Kellerman