Welcome

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© 2013 Agilent Technologies, Inc.

Dr. Raghu K. Settaluri

VP Engineering

Antennas for Communications (AFC)

Antenna Design Automation with

Scripting and Parameterized EM Analysis

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Dr. Raghu K. Settaluri

Vice President, Engineering

Antennas For Communications (AFC)

Ocala, FL-34474

rsettaluri@afcsat.com

Overview

Scripting

Geometry Examples

Parameterization

Steerable Phased Array Example

Simulation and Data export automation

Summary

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Antenna Engineer’s nightmare

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Problem: A 25 x 25 element array with 3750 geometrical parts and 625

excitation ports. 3D analysis of array behavior is required at a variety of

operational frequencies, look angles, modes of operation, amplitude tapering

Scripting

Powerful but infrequently explored feature

Extends the scope of the user interface

Could lead to customer created personal design tool-box

Results in automation and ease for creation of geometries, simulation and post-simulation analyses

When combined with parameterization can result in powerful features

This presentation focuses on two aspects – geometry and simulation

Agilent’s EMPro ver. 2011-12, which has the integrated Python scripting was used as the platform

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Scripting - continued

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UI

Geometry

Definitions

Stimulus

Script

Example of a Script

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Ref: PatchAntenna.py example – EMPro 2011.11

V = empro.geometry.Vector3d

Geometry Example-1

Creation of waveguide transition/waveguide horn antenna using Python scripting

Width and height of the waveguide are functions of length

Automatic geometry generation for linear, parabolic, exponential and cosine-squared tapers

Can be used as a design tool box

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Scripting Highlights

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Script based GUI

Compute W and H for each frustum

Use the loft feature to create each frustum, define material and join

GUI generated using Python scripting

Program flow

Scripting Highlights

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Script for creating

the frustum

Scripting Highlights

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Sample script for

exponential taper

Geometry Examples - Horns

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Exponential Horn

Cosine-squared Taper

2 or 3

Geometry Examples - Transitions

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A waveguide taper

Standard

waveguide to

Tallguide®

Transition

Cavity Backed Patch Antenna

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Patch

Metal

Cavity Substrate Feed

Cavity Backed Patch Antenna -

Continued

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Patch

Metal Cavity

Outer Conductor

Substrate

Teflon

Pin

Script – Various objects

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Metal Cavity

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Feed Definitions

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Phased Array Antenna

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a1,

1 a1,

1 a1,

1 a1,

1 a1,

1 a1,

1 a41

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a1,

1 a1,

1 a1,

1 a1,

1 a1,

1 a1,

1 a31

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a1,

1 a1,

1 a1,

1 a1,

1 a1,

1 a1,

1 a21

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a1,

1 a1,

1 a1,

1 a1,

1 a1,

1 a1,

1 a11

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Steerable

beam

Antenna

elements

Amplitude

and Phase

control

Far-Field Calculation

P(r, ,φ)

2/7/2013 20

Array Geometry through Scripting

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With M and N known, cavity based microstrip elements are created iteratively.

X- or Y-offset can be pre-defined.

Feed locations can be iteratively drawn as well.

Each feed port will be assigned a unique amplitude and phase depending on the required look angle of the array.

A 49-element Phased Array

(Rectangular lattice)

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Top View Bottom View

A 625-element Phased Array with

Triangular Lattice

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Top View Bottom View

Script Highlights -Geometry

The entire array was created using

scripting.

M, N, element offset, material properties

and feed location can be specified.

The 50Ω feed port excitation for every

element was automatically created.

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Typical simulation Requirements

Return Loss behavior of the array

element in the array environment

The beam steering towards ( o, o)

Side-lobe level control (beam shaping)

Array operable in sum-mode,

azimuth/elevation difference modes

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Challenges

A 25 x 25 element array has 3750 geometrical parts and 625

excitation ports. Each script run takes about 30-45 minutes

to generate the geometry and assign the ports.

For a given beam pointing direction and frequency, each

element dictates a unique phase of the feed signal.

The amplitude at every feed port is a function of the side-

lobe level requirement.

The element excitations also depend on the mode of

excitation: sum-mode, azimuth/elevation difference modes.

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Scripting with Parameterization

Using scripting to generate parameters and parameter based equations instead of absolute values for one simulation case.

For a given array size, the geometry is generated only once.

All excitation controls are now parameterized in terms of user-given independent variables, such as frequency of the RF signal, beam pointing angles, and amplitude tapering requirement.

In essence, the complexity associated with multiple cases of analysis simply reduces to re-defining the independent input variables at simulation level.

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Array Example -1

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A 49-element C-band Cavity Backed Phased Array antenna

(M=7,N=7; rectangular patch)

Designed for a center frequency of 5.5 GHz

49-element array –Radiation

characteristics of the element

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Return Loss Element Gain

Amplitude Tapering of the Array

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0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Amplitude Distribution - 35 dB Elliptic Taper

Python Script

Data file format

Ataper =0 No Taper

Ataper =1 Taper required

Three Modes of Operation

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Sum Mode: Elements in all quadrants are in phase.

Azimuth-Difference Mode: Elements in B and D quadrants are

out of phase with those from A and C.

Elevation-Difference Mode: Elements in C and D quadrants are

out of phase with those from A and B.

Mode LeftLower LeftUpper RightLower RightUpper

Sum 1 1 1 1

Elevation

Difference

-1 1 -1 1

Azimuth

Difference

1 1 -1 -1

Script generated Parameter output

for Beam Control (amplitude)

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User Inputs: Ataper, Mode values, T,P, fo

Script generated Parameter output

for Beam Control (Phase)

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625 Element Phased Array @ 5.5 GHz

Sum Mode Beam Steering - =0 =0

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Ataper =0 Ataper =1

625 Element Phased Array @ 5.5 GHz

Sum Mode Beam Steering - =0 =0

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2D Radiation Pattern for sum-mode (with and without amplitude tapering)

625 Element Phased Array @ 5.5 GHz

Sum Mode Beam Steering - =30 =30

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Ataper =0 Ataper =1

625 Element Phased Array @ 5.5 GHz

Azimuth Difference Mode: Beam Steering

=0 =0

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Ataper =0 Ataper =1

625 Element Phased Array @ 5.5 GHz

Azimuth Difference Mode: Beam Steering

=30 =30

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Ataper =0 Ataper =1

625 Element Phased Array @ 5.5 GHz

Elevation Difference Mode: Beam Steering

=0 =0

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Ataper =0 Ataper =1

625 Element Phased Array @ 5.5 GHz

Elevation Difference Mode: Beam Steering

=30 =30

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Ataper =0 Ataper =1

Simulation Automation through

Scripting

To automatically create a series of

simulations for array analysis

Multiple input variables and ranges

Provision for over-night/multi-night

analyses

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Simulation Automation through

Scripting

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Exporting Results through Scripting

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Usage:

Summary

Scripting can be an extremely useful tool for geometry generation.

When combined with parameterization, it could lead to flexible simulation control for certain geometries.

This presentation provides examples of waveguide transitions and steerable phased array through scripting and parameterization.

Additional features such as automatic multi-case analysis and post-simulation processing have also been demonstrated through scripting.

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Acknowledgments

I would like to thank Mr. Marc Petersen and Mr.

Bram Degreve of Agilent Technologies for

continued support and helpful discussions.

I would also like to thank Agilent Technologies

and Microwave Journal for arranging this

Webcast.

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Contact Information

Dr. Raghu K. Settaluri,

Vice President, Engineering,

Antennas For Communications (AFC)

2499 SW 60th Ave., Ocala, FL-34474

rsettaluri@afcsat.com, Phone: (352) 687-4121

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