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Master Thesis

Control and Prediction of Scan Blindness Effects in Printed Planar Antenna Systems

Bahram Sanadgol

Universität Duisburg-Essen: Prof. Dr.-Ing. K. Solbach

Dipl.-Ing. Oliver Litschke, IMST GmbH

Presentation Outline

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Waveguide Simulator

Blindness Concept

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TM TE

•Null in Pattern •Scan Coverage •Big Mismatch in Input Impedance •No Feeding Possible

E E

Substrate u=sin θ cos Ф

Surface Wave Circle Diagram

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Scanning Part

Blind

Spot

Blindness in Visible Space

TM (TE) mode excitation

X→0.55λ

y→ 0.5 λ and β=1.3

Scan Impedance Method and SEP

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Effective Propagation Constant

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TM Mode β Calculation

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TE Mode β Calculation

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Substrate Mode Ideal β Calculated

β Substrate1 TM 1.1349 1.145

Substrate2

2

TM 1.6168 1.597

Substrate2 TE 1.1316 1.109

ε=3.25

h=0.101λ

ε=4

h=0.181λ

Substrate Mode β

effective

β

Theory

Substrate1 TM 1.124 1.1349

Substrate2 TM 1.4 1.6168

Substrate2

TE 1.177 1.1316

Printed Dipole

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Method Comparison for Dipole

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Spacing Spacing

Surface Wave

SEP Scan

Impedance

β effective

Surface Wave

SEP Scan

Impedance

β effective

(1.1349)

(1.6168)

Spacing Substrate Surface Wave SEP Scan Impedance β Effective

Patch Array

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Arrays of Microstrip Patches

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Scan Element Pattern

ε=3.48

h=0.121λ β=1.2383

Scan Resistance, E-plane

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Scan Reactance, E-plane

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Scan Resistance, H-plane

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Scan Reactance, H-plane

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E-plane Farfield and Comparison

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Spacing Surface Wave SEP Scan Impedance β effective

Element Spacing= 0.55 λ

Blindness Control

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Wall’s Functionality

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18 GHz 24 GHz

Effect of Wall on Resonant Frequency

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Near Field Interference

Frequency Up-shift

Match Improvement from Suppressed Surface Wave

Single Element Tuning

Wall Effect on Blindness

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Blind Spot is moved toward grating lobe.

Element Spacing= 0.55 λ

Surface

Wave is

Suppressed

SEP Analysis

Grating Lobe at 55

β close to 1

Farfield Comparison

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50

Element Spacing= 0.55 λ

Waveguide Simulator

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Wav

egu

ide

Po

rt

Ele

men

t P

ort

Dipole Array, Spacing o.5λ

3*3 on a substrate with h=0.181λ

28°

24 GHz

E-plane

Farfield

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Farfield pattern of a 1inear array of 17 dipoles on a

substrate with ε=4.2 from Scan Impedance Method

Conclusion and Future Work

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•Blindness prediction for dipoles and patches

•New method based on β calculations

•Blindness control

•Waveguide simulation as comparison

•β calculations for other single elements

•Optimized feeding network

•Another suppressing structures

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Patch Serial Feeding

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Why? Simple Feeding Network

Easy to introduce phase shifters

Disadvantages

Pin’s Spurious Radiation

Amplitude Distribution

Amplitude Distribution and Layout

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Farfield of Series Patches

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