Gradient permittivity film

A gradient permittivity film comprising:

• a first permittivity layer comprising a first continuous matrix of a first material having a first relative permittivity (εr1) and a second component having a second relative permittivity (εr2) dispersed in the first continuous matrix, the first permittivity layer having a first effective layer relative permittivity (ε1) and a thickness (T1);
• and
• a second permittivity layer having a second effective layer relative permittivity (ε2) and a thickness (T2) disposed on the first permittivity layer;
• wherein the gradient permittivity film has a haze greater than 50% or a transmission of visible light less than 50%;
• and
• wherein:
• ε1 is greater than ε2 by at least 10% for at least one frequency (f) within a frequency range between 20 GHz and 300 GHz,
• ε
• 1
• =
• 1.1
• to
• ⁢
• 10
• ⁢
• ε
• 2
• =
• 1.11
• to
• ⁢
• 10
• ⁢
• T
• 1
• =
• 0.8
• (
• t
• 1
• )
• ⁢
• to
• 1.2
• (
• t
• 1
• )
• ,
• where
• ⁢
• t
• 1
• =
• c
• 2
• ⁢
• f
• ⁢
• ε
• 1
• ⁢
• T
• 2
• =
• 0
• .
• 8
• ⁢
• (
• t
• 2
• )
• ⁢
• to
• 1.2
• (
• t
• 2
• )
• ,
• where
• ⁢
• t
• 2
• =
• c
• 4
• ⁢
• f
• ⁢
• ε
• 2
• εr1 is greater than εr2 for the frequency.