pps uetliberg-antenna wireless lan antenna...

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PPS Uetliberg-Antenna

Wireless Lan Antenna competition Summer 2011

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Antennas Simulation Competition Timetable Informations

Outline

• Antenna Fundamentals

• Simulation

• Competition

• Timetable

• General information

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Antennas Simulation Competition Timetable Informations

Antenna Fundamentals

Antennas

transmission line antenna free space

E-field amplitude

at the E-plane:

Source

Antenna:

A component which takes electromagnetic energy from free space and

directs it into a transmission line (or vice versa = Reciprocity)

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Antennas Simulation Competition Timetable Informations

Antenna Fundamentals

Antennas

Far Field Approximation

Gain (Gewinn)

Directivity (Richtfaktor)

Input impedance, reflection factor

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Antennas Simulation Competition Timetable Informations

1) Wire antennas

Electrically small: Resonant:

Dipole Loop Antennas Helix

<<l <<l ≈ l/2

-Low directivity

-Low efficiency

-Small input impedance

-High input reactance

-Real input impedance

-Small bandwidth

Wide band:

- Bandwidth >2:1

- example:

Log periodic dipole Array

Antennas

Different antenna types

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Antennas Simulation Competition Timetable Informations

2) Aperture antennas

Antennas

Different antenna types

Pyramidal

horn

Conical

horn

Rectangular

waveguide

Rectangular

Patch

Circular

Patch

-Micro- and millimeter wave

-High directivity

-Medium bandwidth

-Size: some wavelength

3) Microstrip antennas

-Micro- and millimeter wave

-Low directivity

-Low effeciency

-Resonant structure

-Small bandwidth

-Very cheap to maufacture (PCB technique)

-Flat design, easy to integrate

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Antennas Simulation Competition Timetable Informations

Fields from the elements in the

array interfere constructively for

certain directions ( maxima)

and destructively for other

directions ( nulls) maximum S

SS

minimum

(~zero) Array antenna

=

-allows to increase the gain for most antennas

-very space consuming

´

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Antennas Simulation Competition Timetable Informations

mobile communication

Antennas

GSM

880 - 960 MHz

1710 - 1880 MHz

max. power: 2 W

UMTS

1920 – 1980 MHz uplink

2110 – 2165 MHz downlink

max. power: 0.25 W

Wlan

2412 – 2484 MHz

max. power: 0.1 W

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Antennas Simulation Competition Timetable Informations

Simulation software

• Finite Elemente (FEM)

– Solver for discrete frequencies

– Tetrahedal volume discretisation

– computes fields within the

computational domain

• Post processing computes

field patterns and network

entities

• CAD user interface to define

the geometry

• HFSS, CST, COMSOL

Simulation

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Antennas Simulation Competition Timetable Informations

Yagi – Antenna

Surface currents

Simulation

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Antennas Simulation Competition Timetable Informations

Yagi – Antenna

Electric field strength distribution

Simulation

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Antennas Simulation Competition Timetable Informations

Far field calculations - Matching

Simulation

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Antennas Simulation Competition Timetable Informations

Directivity plots

3D plot Cartesian plot

Simulation

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Antennas Simulation Competition Timetable Informations

Simulation Software HFSS

• High-Frequency Structure Simulator (HFSS) using FEM

• Available on tardis!

• Support CAD input

• Automatic discretisation of volumes by means of tetrahedra

• Solver computes the fields inside the whole domain

• Absorbing boundaries imitate the extension to infinity

• Antenna parameters are extratcted based on the field values

• Suitable for complex geometries and materials

Simulation

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Antennas Simulation Competition Timetable Informations

Wireless LAN antenna competition

Competition

• Objectiv: build a high gain Wireless LAN antenna

• teams of 2 or 4 persons

• personal guidance for each group

• use literature, simulation software, internet and build it

• test your ideas @ home with a simple WLAN adapter

• final measurement in our antenna room on May 11th

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Antennas Simulation Competition Timetable Informations

Wireless LAN antenna competition

Competition

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Antennas Simulation Competition Timetable Informations

PPS testat conditions

• build an high gain antenna – your design

• Simulation of the antenna pattern

• Measurement of the antenna pattern (2D)

• 10 page report

– english or german

– Includes antenna theory, simulation and measurements

• 10 minute presentation (english)

Competition

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Antennas Simulation Competition Timetable Informations

PPS Timetable

gather Antenna Fundamenals

Simulation Measurements

Optimization

Presentation and Report

Theory

Praxis

Documentation

Timetable

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Antennas Simulation Competition Timetable Informations

Timetable

• March 2nd 2011 Introduction

• Individually EMF 1 – Fachpraktikum

• March 9th 2011 Introduction to HFSS

• March 16nd 2011 Demonstration for measurements @ home

• April 2011 biweekly meeting of each group

• May 12th 2011 (?) visit of the Uetliberg Tower

• May 19th 2011 Wire LAN antenna competition

• June 1st 2011 Presentation of your results (report and talk)

Timetable

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Antennas Simulation Competition Timetable Informations

General Information

• Homepage

http://www.ifh.ee.ethz.ch/~fieldcom/pps-antenna/

• simulation sofware HFSS:

http://www.ansoft.com/products/hfss

• literature:

„Antenna Theory, Analysis and Design”, Constantin A. Balanis, 1997

„Antennenbuch”, Karl Rothammel, 1984

Versuchsanleitung Fachpraktikum Antennen (AW, EMF1)

Skript „Felder und Komponenten II“

• contact:

Dimitra Psychogiou, pdimitra@ifh.ee.ethz.ch, x27826, ETZ-K60.1

Christian Beyer, cbeyer@ifh.ee.ethz.ch, x27625, ETZ-K87

(Thomas Kaufmann, thomaska@ifh.ee.ethz.ch, x25007, ETZ-K60.1)

Infos