Classical Electrodynamics Applied in Modern Technology Günter Nimtz Physics Department, University of Cologne 1. Properties of Nano-Metal Films 2. Anechoic.

Classical Electrodynamics Applied in Modern Technology

Günter Nimtz

Physics Department, University of Cologne

1. Properties of Nano-Metal Films2. Anechoic EMC Chambers: Pyramidal Absorber 3. Absorption by Anechoic Traps: Reflecting Curtains4. Ferrite Tile Absorber……….Hybrid Absorbers5. Rain Sensing Wipers: Frustrated Total Internal

Reflection = Tunneling

Free carrier EM interaction : Drude (1900), Hagen & Rubens (1902)

Nano metal films (gravimetrical determination !)Infrared studies on Absorption, Reflection and Transmission: A + R + T = 1 Murmann; Barnes; Czerny; Woltersdorff (1929 – 1934)

R + T + A = 1of Nano-Film ResistanceAngle of incidence =

TM = 450

EM = 450

= 900

A T R

l> d

T = {1 + Zo/(2 Z)}-2 ;

Zo vacuum impedance

Z =/d sheet resistance d film thickness

How to get a huge metal cavity behave like free space with : ZO = 377 Ω, i.e. no standing wave patterns? Install absorbers at the walls!

EM anechoic chambers

Install absorbers at the walls!Metal walls

EM Anechoic Chamber

Nano-Metal-Film, a 10 nm metal film vapor deposited on 10 µm polyethylene film

d

Sheet Resistance Z is Relevant for Wave Propagation if » d :

Z = 1/( d)

= conductivityd = film thickness = wavelength Foam ≈ 10-7 Nano-Metal Film (≈ 0.1 S/m) (≈ 106 S/m)

d

International Patents: G. Nimtz and A. Enders (1998)

2.4 m

Absorbing Pyramids: Absorption with Low Reflection

E = electric field

E

Standing Waves in Front of the Metal Wall

Z = 0

Nano-film

Foam

Variation of impedance with position along the line (Smith Diagram)

Z

Z = Ω ≈ 377 Ω Shunt No Reflection

/4

EMetal

Vacuum Impedance Z0 = 377 Ω

The variation of impedance with position along the line (Smith Diagram)

R + T + A = 1of Nano-Film ResistanceAngle of incidence =

Special Property :

For 188 Ω:

0.25 + 0.25 + 0.5 = 1

TM = 450

EM = 450

= 900

A T R

> d

e.g. 8 Reflections: R(total) = 0.258 - 48 dB; dB = 10 lg(P1/P2)

Anechoic trap

Transmitter

nano-Metal Films

Novel Principle, Device under Test: Absorption by Multiple Reflection

Metal Wall

Nimtz and Panten, Ann. Phys. 19, 53 (2009); Pending Patents, G. Nimtz (2008)

Curtains of nano Films instead of Pyramids at one wall as shown next figure

EM AnechoicChamber

In small Chambers: Ferrite Tiles with ZF ≈ Z0 6.3 mm; 30 MHz – 300 MHz (< -20 dB, regulation)

Hybrid Absorber: Pyramidal Absorber + Ferrite Tile(30 – 18 000 MHZ)

Metal Wall

ZF = Z0 µr/r = Z0 !

Reflection R: R = (n1 – n2)/(n1 + n2)

= (ZF – Z0)/ZF + Z0)

Ferrite tiles TDK (Ni-Cu-Zn) :

Rain sensing wiper: frustrated total reflection

Total Reflection if:

sin n2/n1

tot = arc sin(n2/n1)

Frustration : tot

glass n1 > n2

air

ß

The double prisms: frustrated total internal reflectionThe analog of quantum mechanical tunneling Sommerfeld (1954)

Front windshield

Prism

Rain…….

LED

Receiver

Rain Sensing Wipers:

Frustrated total reflexion

Rain represents the second prism

• Nano-Metal Film Absorbers are Broad Band Absorbers, Superior to Carbonized Foam Absorber

• Incombustible. Non-Toxic. No Hazardous Waste• Nano-Metal Film Absorbers on Duty since 1995

• Ferrite Tiles, very thin but expensive (30-400 MHz)• Frustrated total internal reflection

as rain sensing car device. • Double Prisms: Newton 1700, BOSE 1900,

Sommerfeld 1954

Summing Up :