Standard Test Method for Measuring Relative Complex Permittivity and Relative Magnetic Permeability of Solid Materials at Microwave Frequencies Using Coaxial Air Line (Includes all amendments and changes 10/18/2022).
Die Annotation des Normtextes ASTM D7449/D7449M-22a :
Keywords:
coaxial line, dielectric constant, loss factor, magnetic permeability, measurement, microwave, millimetrewave, permittivity, radio frequency, scattering parameter, transmission/reflection,, ICS Number Code 17.220.20 (Measurement of electrical and magnetic quantities)
Ergänzende Informationen
Significance and Use
5.1?Design calculations for radio frequency
(RF), microwave, and millimetre-wave components require the
knowledge of values of complex permittivity and permeability at
operating frequencies. This test method is useful for evaluating
small experimental batch or continuous production materials used in
electromagnetic applications. Use this method to determine complex
permittivity only (in non-magnetic materials), or both complex
permittivity and permeability simultaneously.
5.2?Relative complex permittivity (relative
complex dielectric constant), , is the proportionality factor that
relates the electric field to the electric flux density, and which
depends on intrinsic material properties such as molecular
polarizability, charge mobility, and so forth:
Note 1:?In common usage the word relative is frequently
dropped. The real part of complex relative permittivity ( ) is
often referred to as simply relative permittivity, permittivity, or
dielectric constant. The imaginary part of complex relative
permittivity ( ) is often referred to as the loss factor. In
anisotropic media, permittivity is described by a three dimensional
tensor.
Note 2:?For the purposes of this test method, the media is
considered to be isotropic and, therefore, permittivity is a single
complex number at each frequency.
5.3?Relative complex permeability, , is the
proportionality factor that relates the magnetic flux density to
the magnetic field, and which depends on intrinsic material
properties such as magnetic moment, domain magnetization, and so
forth:
Note 3:?In common usage the word relative is frequently
dropped. The real part of complex relative permeability ( ) is
often referred to as relative permeability or simply permeability.
The imaginary part of complex relative permeability ( ) is often
referred to as the magnetic loss factor. In anisotropic media,
permeability is described by a three dimensional tensor.
Note 4:?For the purposes of this test method, the media is
considered to be isotropic, and therefore permeability is a single
complex number at each frequency.
5.4?Relative permittivity ((relative
dielectric constant) (SIC) ?'(?r)) is
the real part of the relative complex permittivity. It is also the
ratio of the equivalent parallel capacitance, Cp, of a
given configuration of electrodes with a material as a dielectric
to the capacitance, C?, of the same configuration of
electrodes with vacuum (or air for most practical purposes) as the
dielectric:
Note 5:?In common usage the word relative is frequently
dropped.
Note 6:?Experimentally, vacuum must be replaced by the
material at all points where it makes a significant change in
capacitance. The equivalent circuit of the dielectric is assumed to
consist of Note 7:?Note 8:?The series capacitance is larger than the parallel
capacitance by less than 1 % for a dissipation factor of 0.1, and
by less than 0.1 % for a dissipation factor of 0.03. If a measuring
circuit yields results in terms of series components, the parallel
capacitance must be calculated from Eq 5 of Test Methods
D150 before the corrections
and permittivity are calculated.
Note 9:?The permittivity of dry air at 23 ?C and standard
pressure at 101.3 kPa is 1.000536. Its divergence from unity, ?' ?
1, is inversely proportional to absolute temperature and directly
proportional to atmospheric pressure. The increase in permittivity
when the space is saturated with water vapor at 23 ?C is 0.00025,
and varies approximately linearly with temperature expressed in
degrees Celsius, from 10 ?C to 27 ?C. For partial saturation the
increase is proportional to the relative humidity.
1. Scope
1.1?This
test method covers a procedure for determining relative complex
permittivity (relative dielectric constant and loss) and relative
magnetic permeability of isotropic, reciprocal (non-gyromagnetic)
solid materials. If the material is nonmagnetic, it is acceptable
to use this procedure to measure permittivity only.
1.2?This
measurement method is valid over a frequency range of approximately
1 GHz to over 20 GHz. These limits are not exact and depend on the
size of the specimen, the size of coaxial air line used as a
specimen holder, and on the applicable frequency range of the
network analyzer used to make measurements. The size of specimen
dimension is limited by test frequency, intrinsic specimen
electromagnetism properties, and the request of algorithm. For a
given air line size, the upper frequency is also limited by the
onset of higher order modes that invalidate the dominant-mode
transmission line model and the lower frequency is limited by the
smallest measurable phase shift through a specimen. Being a
non-resonant method, the selection of any number of discrete
measurement frequencies in a measurement band would be suitable.
The coaxial fixture is preferred over rectangular waveguide
fixtures when broadband data are desired with a single sample or
when only small sample volumes are available, particularly for
lower frequency measurements.
1.3?The
values stated in either SI units of in inch-pound units are to be
regarded separately as standard. The values stated in each system
are not necessarily exact equivalents; therefore each system shall
be used independently of the other. Combining values from the two
systems is likely to result in non conformance with the standard.
The equations shown here assume an e+j?t harmonic time
convention.
1.4?This standard does not purport to
address all of the safety concerns, if any, associated with its
use. It is the responsibility of the user of this standard to
establish appropriate safety, health, and environmental practices
and determine the applicability of regulatory limitations prior to
use.
1.5?This international standard was
developed in accordance with internationally recognized principles
on standardization established in the Decision on Principles for
the Development of International Standards, Guides and
Recommendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
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