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Prepared by : MD. NAVID BIN ANWAR

M. Number: 314848

Supervisor: Xuan Anh Nghiem

Prof. Dr. sc. techn. Renato NegraAssistant Professor, Mixed-Signal CMOS circuits

BODY SCANNERREFLECTOMETER

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Introduction

Reflectometer

*The reflectometer is a measurement device that is

mainly used in high-frequency electronics. It allows

one to measure the amplitude ratio or the phase

difference of two electromagnetic waves or both ofthem. The most frequent use of this device is for

measuring the so-called complex reflection

coefficient of a device under test (DUT), which is the

ratio of the wave reflected by the DUT to the wave

incident to the DUT.

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Six-Port Reflectometer Over

Four-Port Network Analyzers*Simple structure

*Requirement for fewer components

*Measure only the amplitude (or power) of

signals

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REFLECTOMETER DESIGN

*Waveguide 6-ports

*1826.5 GHz (WR-42)3

*26.540 GHz (WR-28)

*4050 GHz (WR-22)

*5075 GHz (WR-15)

*75110 GHz (WR-10)

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REFLECTOMETER DESIGN* A. WR-15 Reflectometer: (V-band (5075 GHz))

The six-port module, shown in Fig. 1, consists of asection of WR-15 waveguide and three probe channels thataccommodate microstrip waveguide probes with integratedzero-bias Schottky diode detectors. Note that because onlythree detectors are utilized, the reflectometer is actually afive ports (which can be considered a simplified version of thesixport). Provided the device to be measured is known apriori

to be passive, only three detectors are required to uniquelydetermine its reflection coefficient. The fourth detector maybe used to enhance measurement accuracy, but strictly is notrequired. Bias protection circuits are included in the detectoroutput to reduce the likelihood of damage to the zero-biasSchottky diodes through electrostatic discharge.

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Body Scanning by

Reflectometer*Image Focusing

By means of a lens or by an extended

aperture. The beamwidth of an aperture

antenna is related to its size and thefrequency which usually leads to huge

apertures.A drawback is the field ofviewwhich is only big enough to fit onto a person

several meters away from the sensor and

only in the farfield a sharp beam isgenerated.

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Body Scanning by

Reflectometer*The MMW systems are based on a real-time mechanical

scanning architecture. They can image hidden objects and are

an alternative for security applications.

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Imaging System

*The MMW image recovers the objects beneath theclothes very well. The image also shows a major

disadvantage of perpendicular illumination. Parts of

the body, which are directed perpendicular with

respect to the incident field lead to spots of high

reflectivity which overlay the received signal fromthe objects and clutter the image. The specular

reflections are highly dependent on the TXDUTRX

geometry and change rapidly as this geometry

varies. To overcome that problem it is advisable to

sense the DUT from many viewing angles.

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