# Nano metal films

```Classical Electrodynamics
Applied in Modern Technology
Günter Nimtz
Physics Department, University of Cologne
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Properties of Nano-Metal Films
Anechoic EMC Chambers: Pyramidal Absorber
Absorption by Anechoic Traps: Reflecting Curtains
Ferrite Tile Absorber……….Hybrid Absorbers
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
A
T
R+T+A=1
of Nano-Film Resistance
Angle of incidence = 
 = 900
> d
T = {1 + Zo/(2 Z)}-2 ;
TM = 450
Zo vacuum impedance
Z =/d sheet resistance
d film thickness
EM  = 450
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
Metal walls
Install absorbers at the walls!
EM Anechoic Chamber
Nano-Metal-Film, a 10 nm metal
film vapor deposited on 10 µm
polyethylene film
Sheet Resistance Z is Relevant
for Wave Propagation if  » d :
Z = 1/( d)
d
d
 = conductivity
d = film thickness
 = wavelength
 Foam ≈ 10-7  Nano-Metal Film
(≈ 0.1 S/m)
(≈ 106 S/m)
2.4 m
International Patents: G. Nimtz and A. Enders (1998)
Standing Waves in Front of the Metal Wall
Variation of impedance Z with position along the line
(Smith Diagram)
Absorbing Pyramids: Absorption with Low Reflection
Z=0

Foam
E
Nano-film
E = electric field
Vacuum Impedance
Z0 = 377 Ω
Metal
E
/4
Z=Ω
≈ 377 Ω Shunt
No Reflection
The variation of impedance with position along the line
(Smith Diagram)
R
A
T
R+T+A=1
of Nano-Film Resistance
Angle of incidence = 
 = 900
>d
Special Property :
TM = 450
For 188 Ω:
0.25 + 0.25 + 0.5 = 1
EM  = 450
Novel Principle, Device under Test:
Absorption by Multiple Reflection
e.g. 8 Reflections: R(total) = 0.258
- 48 dB; dB = 10 lg(P1/P2)
Transmitter
Anechoic trap
nano-Metal Films
Metal
Wall
Nimtz and Panten, Ann. Phys. 19, 53 (2009); Pending Patents, G. Nimtz (2008)
Curtains of
nano Films
Pyramids
at one wall as
shown next
figure
EM Anechoic
Chamber
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)
ZF = Z0  µr/r = Z0 !
Reflection R:
R = (n1 – n2)/(n1 + n2)
= (ZF – Z0)/ZF + Z0)
Metal
Wall
Ferrite tiles TDK (Ni-Cu-Zn) :
Rain sensing wiper: frustrated total reflection
glass
n1
> n2
air
Total Reflection if:
sin   n2/n1

ß
tot = arc sin(n2/n1)
Frustration :
  tot
The double prisms: frustrated total internal reflection
The analog of quantum mechanical tunneling
Sommerfeld (1954)
Rain Sensing Wipers:
Front windshield
LED
Frustrated total reflexion
Rain represents the second prism
Prism
Rain…….
Summing Up :
• 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
```
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