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Implementation of a phased arrayantenna for the 2.45 GHz ISM band

Presented By:

Alejandro Fuentes 260725

Ricardo Prez 260769

National university of Colombia

GMUN - CMUN group2008

Conrad project and our project logos.

http://gmun.unal.edu.co/cmun

Undergrad thesis

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Block diagram for field test setup

UNAL 2008 Page 2

Source: [1]

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UNAL 2008 Page 3

Measurements of radiation patterns

Use standard spherical coordinate system for antenna measurements.

Source: [2]

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Basic antenna-range configurations

The test antenna is rotated about a appropriate axis.

UNAL 2008 Page 4

Fixed-line-of-sight

Movable-line-of-sight

The source antenna is moved trough to the circumference centered

at the phase center of the test antenna.

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Characterize completely measure: relative amplitude, relative

phase, polarization and power gain.

Characterize is function of space coordinates.

R is fixed and , are variables in a given radiation pattern.

Frecuency of operation is a parameter.

UNAL 2008 Page 5

Antenna radiation field characterization

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The coupling between source and test antennas.

The transverse and longitudinal amplitude taper of the

illuminating wave front.

The phase curvature of the illuminating wave front.

Interference from spurious radiating sources.

UNAL 2008 Page 6

Considerations

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FAR-FIELD MEASUREMENTS

UNAL 2008 Page 7

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UNAL 2008 Page 8

Source: [4]

Elevated range (free-space)

Use when test and source antennas are located on roofs or towers, etc.

Design over a flat area.

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UNAL 2008 Page 9

Source: [2]

Slant range (free-space)

Use less land than elevated range.

Be careful with materials of tower.

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UNAL 2008 Page 10

Source: [4]

Compact range (free-space)

Create uniform plane wave in short distances.

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UNAL 2008 Page 11

Source: [4]

Ground reflection range

Use reflections to create constructive interference.

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UNAL 2008 Page 12

Elevation range is common in medium size antennas

measurement.

The compact range is limited by antenna size and low

operation frequency range.

In outdoor ranges external signals cause measurement

errors, this effects can be eliminated by sharp filters.

Considerations

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NEAR-FIELD MEASUREMENTS

UNAL 2008 Page 13

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Types

Planar near-field

Cylindrical near-field

Spherical near-field

UNAL 2008 Page 14

1. Separation between source and test antenna about 4 or 10wavelengths.

2. Use small RF antenna as source antenna.

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Planar near-field measurement

UNAL 2008 Page 15

Source: [4]

Scan in X and Y coordinates.

Source antenna moves with precision at

the XY plane.

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Cylindrical near-field measurement

UNAL 2008 Page 16

Source: [4]

AUT (Antenna Under Test) gives.

Source antenna moves linearly.

Accurately angular coverage for pattern.

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Spherical near-field measurement

UNAL 2008 Page 17

Source: [4]

AUT gives around Z axis for variable .

Source antenna is fixed in space.

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ANECHOIC CHAMBER

UNAL 2008 Page 18

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UNAL 2008 Page 19

Anechoic chamber

Purpose

Simulate free-space without electromagneticcontamination.

Ideal measurement: uniform plane wave.

Types

Overview

Rectangular anechoic chamber

Tapered anechoic chamberFree-space ranges: null effects ofsurroundings

Reflections ranges: use reflections toproduce plane wave.

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Types

Rectangular anechoic chamber

Tapered anechoic chamber

UNAL 2008 Page 20

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Rectangular anechoic chamber

UNAL 2008 Page 21

Source: [2]

Free-space conditions

Reflect energy to test region

No part of Main lobe is incident upon

sidewalls, ceiling and floor.

Where:

R: Separation between source and test antennas

W: Width or height of chamber

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Tapered anechoic chamber

UNAL 2008 Page 22

Source: [2]

Reflections from sidewalls contribute to field.

Source antenna position is determined

experimentally

High frequencies become more difficult to

place source antenna near to the apex.

Where:

ht: Perpendicular distance from source antenna to

chamber wall

R: Separation between source and test antennas

hr: Perpendicular distance from test antenna to

chamber wall

: Wavelength

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References

1. M. Golio, The RF an microwave handbook, CRC press LLC, 2001, ch. 6, seccin 6.9.

2. Antenna standards committee, "IEEE standard test procedures for antennas," ANSI/IEEE

Std 149-1979, 19 Dec 1979.

3. Orbit/fr Inc, Intorduction to antenna measurement,

http://www.home.agilent.com/upload/cmc_upload/All/ORFR-Theory.pdf4. J. A. Fordham, An Introduction to antenna test ranges, measurements and

Instrumentation, Microwave instrumentations technologies, http://www.lehman-

inc.com/pdf/mag.pdf

UNAL 2008 Page 23

http://www.home.agilent.com/upload/cmc_upload/All/ORFR-Theory.pdfhttp://www.lehman-inc.com/pdf/mag.pdfhttp://www.lehman-inc.com/pdf/mag.pdfhttp://www.lehman-inc.com/pdf/mag.pdfhttp://www.lehman-inc.com/pdf/mag.pdfhttp://www.lehman-inc.com/pdf/mag.pdfhttp://www.home.agilent.com/upload/cmc_upload/All/ORFR-Theory.pdfhttp://www.home.agilent.com/upload/cmc_upload/All/ORFR-Theory.pdfhttp://www.home.agilent.com/upload/cmc_upload/All/ORFR-Theory.pdf