| Summary: | 博士 === 國立臺灣大學 === 電機工程學系 === 86 === This dissertation proposes a new N-way radial power divider/combiner design by
radially combining matched sectorial components. For an
efficient full wave analysis,
a simplified mixed potential integral equation (MPIE) method is
presented to deal
with planar circuits with N-fold rotational symmetry and lumped
elements. The N-
way combining structure sums the power of N devices directly in
one step without having
to proceed through several combining stages. This opens the possibility of such
structure having high combining efficiencies.
The design idea originates from exploiting the symmetry of
radial geometry to
eliminate any amplitude and phase imbalance and in the mean time employing the
sectorial component to serve as the impedance transformer. The
requirement on wide
bandwidth is achieved by incorporating sectorial component with
input and output
matching networks. A systematic design procedure has been
summarized. It includes
the selection of the most appropriate radius and angle of the
sectorial component
by applying radial transmission line theory and the optimal
design of the transmission
lines in the matching networks by commercial software. The new
topology is employed
to design 4-way and 14-way power dividers on the microstrip
medium and the achievable
bandwidth is 30 % and 15 %, respectively, for the criterion of VSWR<1.5.
In order to extract precisely the scattering parameters of
the proposed structures,
the full wave analysis which can take into account the effects
due to fringing field,
radiation, and surface wave leakage should be resorted to. A
numerically efficient
technique for computing the multiport network scattering matrix
of planar structures
with N-fold rotational symmetry is presented. The technique is
based on the solution
of mixed potential integral equation (MPIE) by applying method of moments (MoM)
solution in conjunction with both the triangular and
rectangular basis functions.
The ideal of discrete Fourier transform (DFT) is also
incorporated to reduce the vast
computer memory and CPU time required in the normal MPIE
solution. Numerical results
demonstrate the numerical efficiency and accuracy of the present technique.
The hybrid DFT-MPIE is also extended to solve other
structures which are nearly,
but not exactly, of N-fold rotational symmetry such as disked
type power divider,
five-port circuit, and circular patch antenna. Finally, the
performance degradation
of N-way radial power divider/combiner due to the port failures
is evaluated by DFT
and transmission line theory. Combining turning-off method, the formula of
degradation for N-way radial power divider/combiner with isolation resistors is
exactly derived. Simulated results depict that a power divider/combiner with
optimum isolation resistors is quite robust to the port failures.
|
|---|
