Radiation pattern of an End-tapered helix with parasitic element, designed in Antenna Magus for 16 dBi gain at 1 GHz center frequency. We are pleased to announce the new release of Antenna Magus Version 4.3. This release sees the addition of 5 new antennas: • End-tapered wire helix with parasitic element • Antipodal Vivaldi antenna • Horn reflector (Hogg horn or Cornucopia) • 4 x 1 Pin-fed patch array with underside feed network • Pattern-fed Offset Gregorian reflector Antenna Magus now also has an updated website. A new “resources” section has been added, where users can find application notes, videos and articles focussing on specific antennas and product features. Visit www.antennamagus.com to see more! Users with Floating licenses will be pleased to know that the Floating licence manager has been upgraded, making it possible to automati- cally retrieve licenses from the Magus licensing server. March 2013 Newsletter 4.3 Explore.Design.Deliver. Antenna Magus version 4.3 released! New antennas The End-tapered wire helix with parasitic element is a modification of the Axial-mode helical antenna with linear end-taper – a moderately wide-band, circularly polarised antenna, which is popular in UHF and microwave frequency applications due to its small cross section. The addition of a parasitic helix - as illustrated in the above image - increases the gain of the driven helix without an increase in axial length or diameter. End-tapered wire helix with parasitic element Comparative radiation pattern cuts for an End-tapered helix with and without the parasitic element. [Both antennas de- signed for 16 dBi gain at 1 GHz center frequency] To illustrate the effect of the parasitic element, the dimensions and radiation performance of the two helices (both designed for 16 dBi gain at 1 GHz for a wire diameter of 2 mm) is shown in the previous image. The design which includes the parasitic element requires up to 20% less helical turns and is up to 20% shorter when compared to the standard single wire End-tapered helix. The radiation performance of both helices is very similar. Comparison between the End-tapered helix with and without the parasitic element. [Both antennas designed for 16 dBi gain at 1 GHz centre frequency]
Transcript
Radiation pattern of an End-tapered helix with parasitic element, designed in Antenna Magus for 16 dBi gain at 1 GHz center frequency.
We are pleased to announce the new release of Antenna Magus Version 4.3. This release sees the addition of 5 new antennas:
• End-tapered wire helix with parasitic element• Antipodal Vivaldi antenna• Hornreflector(HogghornorCornucopia)• 4 x 1 Pin-fed patch array with underside feed network• Pattern-fedOffsetGregorianreflector
Antenna Magus now also has an updated website. A new “resources” sectionhasbeenadded,whereuserscanfindapplicationnotes,videosandarticlesfocussingonspecificantennasandproductfeatures.Visitwww.antennamagus.com to see more!
Users with Floating licenses will be pleased to know that the Floating licence manager has been upgraded, making it possible to automati-cally retrieve licenses from the Magus licensing server.
March 2013Newsletter 4.3
Explore.Design.Deliver.
Antenna Magus version 4.3 released!
New antennas
The End-tapered wire helix with parasitic elementisamodificationof the Axial-mode helical antenna with linear end-taper – a moderately wide-band, circularly polarised antenna, which is popular in UHF and microwave frequency applications due to its small cross section. The addition of a parasitic helix - as illustrated in the above image - increases the gain of the driven helix without an increase in axial length or diameter.
End-tapered wire helix with parasitic element
Comparative radiation pattern cuts for an End-tapered helix with and without the parasitic element. [Both antennas de-signed for 16 dBi gain at 1 GHz center frequency]
To illustrate the effect of the parasitic element, the dimensions and radiationperformanceofthetwohelices(bothdesignedfor16dBigainat1GHzforawirediameterof2mm)isshowninthepreviousimage. The design which includes the parasitic element requires up to 20% less helical turns and is up to 20% shorter when compared to the standard single wire End-tapered helix. The radiation performance of both helices is very similar.
Comparison between the End-tapered helix with and without the parasitic element. [Both antennas designed for 16 dBi gain at 1 GHz centre frequency]
Typical longitudinal and transverse gain pattern cuts of the antenna.
Explore.Design.Deliver.
Antipodal Vivaldi
The Antipodal Vivaldi antenna, also known as the dual exponentially taperedslotantenna(DETSA)formspartoftheend-firetaperedslotfamily of antennas. It has several advantages compared to the single exponentially tapered Vivaldi. Probably the most important being its compact size, simple feed and pattern stability.
The Microstrip-fed Vivaldi (already included in Antenna Magus)includes a small matching section, whereas the Antipodal Vivaldi is fed using a simple parallel plate transmission line. Antenna Magus designs the transmission line feed with a characteristic impedance of100Ω.Theparallelplatefeedmaybeconvertedintoamicrostripfeed by simply adjusting the ground plane width to be greater than three times the feed line width. The following image illustrates the difference in feed complexity between the Microstrip-fed Vivaldi and
Design sketch comparing the antenna and feed structures of the Antipodal vs MS-fed Vivaldi antennas.
Typical gain pattern of the Horn reflector.
Antipodal VivaldidesignsinAntennaMagus(itshouldbementioned-asthis is not apparent from the design sketches - that the physical size of the Antipodal Vivaldi is almost half the size of the standard MS-fed Vivaldiwhendesignedtomeetthesameperformanceobjectives).
Typical total gain patterns at fmin, 2.5fmin and 4fmin.
Horn reflector
The Horn-reflector antenna was originally conceptualized at BellTelephoneLabsintheearly1940’sanddevelopedfurtherbyD.C.Hoggat Bell Labs in 1961. It is an adaptation of an offset-fed parabolicreflector or a combination of a square electromagnetic horn and aparabolic reflector – hence Horn reflector. The Horn-reflector is also known as a Hogg horn, Cornucopia or Sugar scoop, due to itscharacteristic shape.
Duetotheshieldingeffectofthehorn,thefarsideandbacklobesareverylow.Thesefeatures,alongwithhighapertureefficiency,makeitvery suitable for use in satellite communication systems.
Sincethe1970’sthisdesignhasbeenlargelysupersededbyshroudedparabolic dish antennas (which can achieve similar sidelobeperformancewithalightermorecompactconstruction)incommercialcommunication systems. In many situations - such as at mm-wave frequencies or where mechanical rotation is required - the Horn-reflector can provide some distinct advantages over other antennaoptions.
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Explore.Design.Deliver.
4 x 1 Pin-fed patch array with underside feed
This 4-by-1 patch array design in Antenna Magus combines the design of the individual patch elements in the array with the design of a corporate feed network realized in microstrip. The feed network is located on a second substrate on the underside of the ground plane, with the patch elements connected to the feed network with pins(vias)thatpassthroughsmallholesinthegroundplane.Thisreduces unwanted coupling between the radiating elements and the microstrip feed network – which may be a consideration when using other feed methods. The 4-by-1 patch array can be used to realize anantennawithafan-shapedbeamandagainofaround13dBiforapplications such as point-to-point communication links. The array is also well suited for use as a sub-array or building-block for larger planar or wrap-around arrays.
Specificsubstrateproperties,aswellastheinputresistancedesiredat the corporate feed point (between 50 Ω and 100 Ω) can bedesigned for in Antenna Magus. The dimensions of a single resonant patch are constrained by the substrate parameters, while the limits on the characteristic impedance of the feed lines are dictated by practical manufacturability considerations. For example, if the feed network design requires microstrip lines with characteristic impedancessignificantlyhigherthansay100Ω,thelinewidthsmay
50 Ω design example at 5.2 GHz on a 787 µm, RT/duroid sub-strate with Er = 2.2.
Example of the feed network designed by Antenna Magus.
become too narrow for etching, depending on the substrate height and relativepermittivity.Conversely,iftheportinputresistanceischosentoo low, the line widths might be unacceptably wide.
The following figure shows a design for 5.2 GHz with 50 Ω inputresistanceona787µm,RT/duroidsubstratewithεr=2.2.
Pattern-fed Offset Gregorian reflector
The Pattern-fed Offset Gregorian reflector is the7thdual-reflector included inAntennaMagusandthe4thGregorian-typereflectorantennatemplate.
Dual-reflectorantennasarebasedonprinciplesthathavebeenusedinopticaltelescopesforcenturies,withCassegrainandGregoriantelescopesdatingbacktothelatesixteenhundreds.Thoughtheseantennassharemanyoftheunderlyingprinciplesofoperationwithtypicalsingle-reflectorstructures, they offermoredesignflexibility and aremore compact.These advantages, however, comeat the cost of an increase in designandmanufacturingcomplexity.Thedual-reflectortopologyallowssubreflectorshapingtobeusedtoincreasethefocus-depthortooptimiseilluminationforanexistingfeedantennaandmainreflector.Byusingadualreflectorwithanoffsetfeed,apertureblockagecanbedecreasedandmountingonaflatorrotatingplatformissimplified.Therearehoweversomefactorslikespill-over,radiationpatternasymmetry,feed/subandmain-reflectoralignmentandothermanufacturingcomplexitiesthathavetobeconsideredwhenchoosinganoffset-feddualreflectortopology.
Summary of the dual reflector antennas in Antenna Magus
Explore.Design.Deliver.
When compared with the Horn-fed Offset Gregorian template, the pattern-fed option reduces simulation time and complexity and makes provision for design based on feed properties such as feed-beamwidth, edge-taper and feed distribution efficiency asillustrated below. Properties of any existing feed antenna can be approximated using the pattern-feed approach, or the desired radiation pattern properties of an ideal feed antenna can be derived from the reflector design.Though a physical feed antenna is notincluded in the pattern-fed design, assumed antenna dimensions are used to ensure that minimal blockage occurs.
Feed antenna pattern properties accounted for by Antenna Magus when designing the Pattern-fed Offset Gregorian re-flector.
Image of the Pattern-fed Offset Gregorian reflector
The Antenna Magus Floating Licence system
(... Pattern-fed Offset Gregorian reflector continued.)
Zoomed view of the normalised radiation pattern.
Normalised radiation pattern of the Pattern-fed Offset Gregorian dual reflector.
3D radiation pattern of the Pattern-fed Offset Gregorian.
AntennaMagusprovidesaflexibleandeasy-to-uselicencingsystem.ThefloatinglicenceprovidesagreatoptionwhereanumberofuserswouldliketohaveaccesstoAntennaMagusfromanyPContheLANwithout having to purchase and maintain node-locked licences for allPC’s.
AnAntennaMagusfloatinglicencesetup(illustratedinthediagram)consists of 3 parts:
1. Install Antenna Magus on a number of client machines which areconnectedtothesameLAN.
2. Install theAntennaMagus floating licensemanager (FLM) onalocallicenceservermachine(connectedtotheLAN)whichprovides licencing information to the client machines as needed.
3. The FLM requires a valid floating license which can beretrieved directly from the Antenna Magus licensing server via the internet or per email request through an Antenna Magus reseller.
