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HFSS online help > Technical Notes >
Radiated Fields >
Antenna Parameters
The accepted power is the time-averaged power (in watts) entering a radiating antenna structure through one or more ports.
Fundamentally in HFSS, accepted power is computed as
|
|
(1) |
where
• Pacc
is the accepted
power in watts.
• Re 
is
the real part of a complex number.
• A
is the union of
all port boundaries in the model, including Wave and Lumped Ports, but
excluding Floquet ports.
• E
is the electric
field.
• H*
is the conjugate
of the magnetic field.
• dS 
is
the local port-boundary unit normal directed into the 3D HFSS model.
Example: Consider the simple case of a single port antenna modeled in a modal project. Then the general expression for accepted power reduces to
|
|
(1) |
where
• |a
|
is the complex modal excitation specified in the Edit Sources window.
• s11 is the single-entry generalized scattering matrix.
Note |
Because the accepted power is calculated from the input signal at the port, a port must be defined for this quantity to be displayed. |
Thus when |s11|
approaches 1 (total reflection), Pacc
approaches zero.
When |s11| approaches 0 (perfect
match), Pacc = |a
|2,
the total power carried by the incident mode.
In the multiport case the physical interpretation of
accepted power can sometimes be confusing. By the fundamental definition,
energy that leaves the antenna structure through a port reduces accepted
power. This, in a multiport antenna, energy cross coupled from an excited
port to a different port reduces accepted power. Therefore in such cases,
even if an excited port is well-matched, Pacc 
may
be small.
In the Edit Sources window of a terminal project, you specify total voltage V instead of model incident power. Using the underlying model S-matrix, HFSS converts the terminal excitation to total fields at the ports, and then applies the general definition.
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Ansys HFSS，Ansoft HFSS online help，Version 15.0. |
HFSS視頻教程 | HFSS教程專欄 | 射頻工程師培訓培訓課程 : Accepted Power'>HFSSComments |