Rev B EMW/FX/BE Daniel Byström2003-11-20 1

Broadband Patch Antenna

Daniel ByströmDesign by: Andreas Wikström

Ericsson Microwave Systems ABFX/BE Antenna and Microwave Design

Rev B EMW/FX/BE Daniel Byström2003-11-20 2

Contents

• Introduction• Prerequisites• Patch Design• Simulation Difficulties• Verification of the Design• Results

Rev B EMW/FX/BE Daniel Byström2003-11-20 3

Introduction

• Broadband antenna elements• Balanced feed• Simulated without balun

Rev B EMW/FX/BE Daniel Byström2003-11-20 4

Prerequisites

• 1 octave bandwidth• Frequency 1-2 GHz• Infinite array• Element spacing λ/2= 75*75mm (2GHz)• Stacked patch antenna• Balanced feed• Ideal 180° hybrid

Rev B EMW/FX/BE Daniel Byström2003-11-20 5

Basic Patch Design

• Dielectric puck• Balanced coaxial feed• Probe inductance compensation

Duroid

Roacell

Teflon

Jordplan Port 1 Port 2

Rev B EMW/FX/BE Daniel Byström2003-11-20 6

Modeling in Ansoft HFSS

• Perf_conductor• Master-/Slave-boundaries• Radiation boundary• PML-layer

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Ideal 180° Hybrid

)(5.0 2112,221111 ,antenna,antennaantenna,antenna,total SSSSS −−+=

• Hybrid calculated with MatLab

180°-hybrid Antenna

1

2

2

4

1

3

Unbalanced port

Termination

Rev B EMW/FX/BE Daniel Byström2003-11-20 8

Simulation Results

E-plane scanning H-plane scanning

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Difficulties

• Problems with radiation boundary for scanned examples• Results are very convergence sensitive when using an

ideal 180°-hybrid

Rev B EMW/FX/BE Daniel Byström2003-11-20 10

Array Simulator Principle

The reflections off the walls of the waveguide are used to make the element behave as though in an array.

Rev B EMW/FX/BE Daniel Byström2003-11-20 11

Array Simulator Model

• ½+1+½ elements are used• Only gives information about one scan-

angle for every frequency

Rev B EMW/FX/BE Daniel Byström2003-11-20 12

Comparing an Array Simulator and an Infinite Array

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Port Adaption

The measured and simulated ports have different impedances

• Coaxial port on patch is 84 Ω• Measured port is 50 Ω

Solution: simulate measured port

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Measured Results Compared to the Simulation

• Excellent match between measured and simulated results!