Optenni Lab Easy-to-use impedance matching tool for antenna - - PowerPoint PPT Presentation

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Optenni Lab

Easy-to-use impedance matching tool for antenna designers

Optenni Ltd, May 22, 2013

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Optenni Lab

• Optenni Lab is a fast and easy-to-use matching circuit

generation and antenna analysis tool tailored for antenna designers

• Main features:

– Fast automatic matching circuit generation including a component library and sensitivity analysis – Simultaneous multiport matching – Estimation of obtainable bandwidth of antennas at various frequencies using the bandwidth potential technique – Calculation of worst-case isolation for two-antenna systems

Optenni Ltd, May 22, 2013

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MATCHING CIRCUIT GENERATION

Main Features of Optenni Lab

Optenni Ltd, May 22, 2013

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Traditional matching circuit generation

• 1. Using a circuit simulator, guess a suitable matching

circuit topology and give initial values for the components

• 2. Set up frequency markers manually
• 3. Try to tune the circuit values by hand
• 4. Try to use the optimization features of the circuit

simulators

• 5. If the results are not good, start again and try

another topology

Optenni Ltd, May 22, 2013

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Problems with the traditional method

• Circuit simulator skills needed
• Theoretical impedance matching knowledge needed

to select the matching circuit topologies

• Difficult to choose a correct topology for

multiresonant cases

• Optimization routines are difficult to use

– Setting frequency ranges is tedious – Optimization criteria might not be the best ones

• Whole process takes many laborious iterations and

possibly hours

Optenni Ltd, May 22, 2013

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Optenni Lab: Matching circuit generation

1. Select antenna impedance file (multiport S parameters from a Touchstone file) 2. Select termination impedances 3. Select frequency ranges 4. Select number of components in matching circuits 5. Click OK

• Whole procedure takes less

than 30 seconds

• No impedance matching or

circuit simulation skills needed

Optenni Ltd, May 22, 2013

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Results of matching circuit generation

Optenni Ltd, May 22, 2013

All previous results available in a project tree S parameters (S11, S21) through the matching circuit S11 on the Smith chart Generated circuit Multiple topologies generated Circuit performance

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Component library

• Optenni Lab includes a library of

commonly used inductors and capacitors

• Initially almost 30 component series

from three major manufacturers are supported and more are planned

• The optimization using components

from the library is fast and easy

• Component library is also compatible

with sensitivity analysis

Optenni Ltd, May 22, 2013

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Sensitivity analysis

• The sensitivity of the results with

respect to component tolerances can be analyzed for both the generic component models and the library models.

• Also yield and minimum

efficiency is calculated

• The sensitivity analysis only takes

a few seconds

Optenni Ltd, May 22, 2013

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Optimization of efficiency

• For matching circuits with lossy matching

components, Optenni Lab is optimizing for S21, which is equivalent to the total efficiency of the matching circuit (including both impedance mismatch losses and thermal losses in the matching circuit components)

• Optimization of the impedance match alone would

lead to suboptimal total efficiency

• In many other programs it is difficult to optimize for

the total efficiency (S21).

Optenni Ltd, May 22, 2013

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Options in matching circuit generation

• Manually given topologies
• Losses in matching circuit

components: S21 of circuit

• ptimized, component

losses calculated

• Fixed component values
• Limits for component

values

• Interactive tuning of

generated circuits

Optenni Ltd, May 22, 2013

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Impedance trace

• Impedance trace shows how

the components change the impedance on the Smith chart at the visualization frequency

• Very useful feature for

understanding the operation of the matching circuit

• Can be combined with

component tuning and interactive selection of the visualization frequency

Optenni Ltd, May 22, 2013

Effect of series capacitor Effect of shunt inductor

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SIMULTANEOUS MULTIPORT MATCHING

Main Features of Optenni Lab

Optenni Ltd, May 22, 2013

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Main features

• Simultaneous multiport matching compatible

with automatic topology creation, component library, tolerance analysis etc.

• For antenna applications: optimization of

efficiency

• For filters or amplifiers: optimization of S21

etc.

• Arbitrary number of ports
• Termination of ports (internal ports for

single components)

Optenni Ltd, May 22, 2013

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Multiport antenna matching

• Not enough to have good matching (e.g. both |S11|2

and |S22|2 small)

• Not enough to have good matching and isolation

(|S11|2 , |S21|2 and |S22|2 small)

• Need to consider antenna total efficiency, taking into

account matching circuit losses and coupling to other ports

Optenni Ltd, May 22, 2013

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Multiport antenna matching

• Easy to use: just click on

the ports to set the frequency ranges and the circuits to set number of components or topology

• Multiple topologies
• ptimized for each port
• Fast parallel optimization

Optenni Ltd, May 22, 2013

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Output data

• Circuit topology
• Efficiencies
• S parameters

Optenni Ltd, May 22, 2013

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Additional options

• Ports can be terminated using a

single component (e.g. internal ports in EM simulations used for component placement)

• Specifications for efficiency stop

bands and isolation

Optenni Ltd, May 22, 2013

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General multiport matching

• Applications: amplifiers, filters, switches, coupled coils

etc.

• Typical figure of merit: |S21|2 to be large in passband

and small in stopband

• Maximum possible |S21|2 given by the concept of

electromagnetic isolation

• Targets: pass and stop bands for Sij

Optenni Ltd, May 22, 2013

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ESTIMATION OF OBTAINABLE BANDWIDTH: BANDWIDTH POTENTIAL

Main Features of Optenni Lab

Optenni Ltd, May 22, 2013

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Estimation of obtainable bandwidth

• The obtainable bandwidth
• f an antenna through a

two-component matching circuit can be quickly estimated using the bandwidth potential technique

• The analysis makes it easy

to compare antenna prototypes (without matching them explicitly)

Optenni Ltd, May 22, 2013

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Benefits of bandwidth potential

• Quikcly shows the obtainable bandwidth of a

prototype without explicit tuning

• Differently matched antennas can be compared
• Can be used to select the best antenna candidate
• Shows at which frequency the best bandwidth is
• btained
• Can be used to verify the antenna operation: best

bandwidth should be obtained at the operation frequency bands

Optenni Ltd, May 22, 2013

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Example of bandwidth potential usage

• Ground plane: 40 mm by 100 mm
• Patch: 25 by 20 mm, height 5 mm

Optenni Ltd, May 22, 2013

Case 1 Case 2: 19 mm by 14 mm removed

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Impedances of example antennas

Optenni Ltd, May 22, 2013

Based on original unmatched impedances it is difficult to say which antenna is more wideband and how large bandwidth could be

• btained.

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Bandwidth potential results

Optenni Ltd, May 22, 2013

Case 1 Case 2 Bandwidth potential calculation shows that antenna 1 is more wideband at the lower operating frequency but antenna 2 is more wideband at the upper frequencies (although the antenna is smaller).

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Bandwidth potential and parameter sweeps

Height of antenna 2 varied

Optenni Ltd, May 22, 2013

Difficult to see the effect of the

• height. Seems to lower the upper

resonance frequency? The maximum bandwidth of the upper resonance stays at the same frequency, lower resonance becomes more wideband. Raw impedance data Bandwidth potential

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Summary of bandwidth potential

• Using raw impedance data it is difficult to compare

differently matched antennas and it is difficult to see how large bandwidth could be obtained with impedance tuning.

• Bandwidth potential calculations show the obtainable

bandwidth at all frequencies, making comparison of different antennas easy. Bandwidth potential can also be used with parameter sweeps.

• Bandwidth potential saves antenna design time and

reduces the number of prototypes.

Optenni Ltd, May 22, 2013

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CALCULATION OF WORST

• CASE ISOLATION

Main Features of Optenni Lab

Optenni Ltd, May 22, 2013

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Calculation of electromagnetic isolation

• Electromagnetic isolation is the worst case isolation at each

frequency when two ports are simultaneously conjugate matched at that frequency.

• It can be used to compare different antenna systems (e.g. in

diversity applications) in terms of their isolation characteristics without matching the ports manually.

Optenni Ltd, May 22, 2013

S21 Electromagnetic isolation

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Usage of electromagnetic isolation

• Electromagnetic isolation can be used to select best

position for diversity antennas.

• Moving the diversity antenna will change the

matching of diversity and main antennas and thus also the antenna isolation. Observed isolation might be large only due to poor matching.

• Electromagnetic isolation shows how the isolation

changes in the case that both antennas would be matched and can thus be used to reliably compare the isolation in different positions.

Optenni Ltd, May 22, 2013

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OTHER FEATURES AND SUMMARY

Optenni Lab

Optenni Ltd, May 22, 2013

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Additional features

• Generation of matching circuits that obtain conjugate

matching to the termination impedance or maximize the bandwidth around a starting frequency

• Calculation of radiation efficiency from impedance

and total efficiency data with different frequency grids

• Capability to read and write project files containing

the previously computed results

• Comparison of different results on the same plot
• On-line manual

Optenni Ltd, May 22, 2013

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Link between CST and Optenni Lab

• A two-way link between

Optenni Lab and CST STUDIO SUITE™ has been developed

• Optenni Lab can be launched

from within CST

• Matching circuits generated

in Optenni Lab can be transferred to CST DESIGN STUDIO™ for further analysis

Optenni Ltd, May 22, 2013

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Advantages of using Optenni Lab

• Fast matching circuit generation
• Rapid estimation of obtainable bandwidth
• Easy comparison and evaluation of antenna

prototypes

• Optimal total antenna performance obtained
• Very intuitive graphical user interface
• Can be easily operated also by nonspecialists
• Developed further based on user feedback
• Optenni Lab increases the productivity of antenna

designers and reduces the design times of antennas

Optenni Ltd, May 22, 2013