Telecommunications – Receiver or analog modulated signal frequency converter – Frequency modifying or conversion
Reexamination Certificate
2000-10-12
2004-12-14
Tran, Pablo N. (Department: 2685)
Telecommunications
Receiver or analog modulated signal frequency converter
Frequency modifying or conversion
C455S081000, C331S1170FE, C333S239000
Reexamination Certificate
active
06832081
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a nonradiative dielectric waveguide used in a high frequency band of, e.g., millimeter-waves and a millimeter wave transmitting/receiving apparatus using such a nonradiative dielectric waveguide.
A first construction example of a conventional nonradiative dielectric waveguide is described with reference to FIG.
34
. In the following, the nonradiative dielectric waveguide is referred to as an NRD guide. The NRD guide shown in
FIG. 34
is constructed by providing a dielectric strip
703
between a pair of parallel plate conductors
701
,
702
whose spacing is &lgr;/2 or shorter when a wavelength of an electromagnetic wave (high-frequency wave) propagating in the air at an operating frequency is &lgr;, and is based on such an operation principle that the electromagnetic wave transmits along the dielectric strip
703
, and radiation of the transmitting wave is suppressed by the blocking effect of the parallel plate conductors
701
,
702
. In
FIG. 34
, the upper parallel plate conductor
701
is partly cut away so as to make the inside visible.
The NRD guide according to the first conventional construction example may include a curved dielectric strip
704
between the pair of parallel plate conductors
701
and
702
. Such a construction enables an electromagnetic wave to easily be transmitted in a curved manner and has advantages of miniaturization of a millimeter wave integrated circuit and a circuit design with a higher degree of freedom. In
FIG. 35
, the upper parallel plate conductor
702
is shown in broken line so as to make the inside visible.
There are known two modes, i.e., an LSM (longitudinal section magnetic) mode and an LSE (longitudinal section electric) mode as millimeter wave transmission mode of the NRD guides. The LSM mode having a smaller loss is generally used. Since the parallel plate conductors
701
,
702
of the conventional NRD guides need to have a high electric conductivity and an excellent processability, conductor plates formed of Cu, Al, Fe, SUS (stainless steel), Ag, Au, Pt or like metallic material have been used. Alternatively, insulating plates made of ceramics or resin having a conductive layer made of the above metallic material formed on the outer surface have also been used.
Teflon (trademark of polytetrafluoroethylene), polystyrene and like resin material having a relative dielectric constant of 2 to 4 have been used for the dielectric strips
703
,
704
due to their good processability. The dielectric strips
703
,
704
have been secured to the parallel plate conductors
701
,
702
by an adhesive.
However, if the NRD guide is constructed by the dielectric strip formed of the conventionally used Teflon, polystyrene or dielectric material having a relative dielectric constant of 2 to 4 in the first conventional construction example, there is a problem that a steeply curved portion cannot be provided because of a bend loss and a large transmission loss at a joining portion of the dielectric strip. Even if a moderately curved portion could be provided, a radius of curvature of the curved portion would need to be precisely determined. However, there is a restriction in precisely setting the radius of curvature if the dielectric strip is made of Teflon, polystyrene or like material.
Further, a bend loss at the curved portion can be suppressed to a practically negligible level by strictly specifying a curvature of the dielectric strip in conformity with the operating frequency. However, the bend loss increases upon even a slight shift of the operating frequency. For instance, if an attempt is made to reduce a bend loss at and near 60 GHz, a width of its permissible range is only about 1 to 2 GHz. This is because, in the case that the NRD guide is formed using a dielectric material having a relative dielectric constant of 2 to 4, part of the millimeter wave of the LSM mode is converted at a curved portion thereof into that of the LSE mode to increase a loss because distribution curves of the LSM mode and the LSE mode are very approximate to each other.
In the case that a high-frequency device, a high-frequency circuit module or the like is fabricated using the NRD guide having the dielectric strips
703
,
704
made of an inorganic compound such as ceramics, it is possible to provide a steeply curved portion at the dielectric strips
703
,
704
, but not possible to provide a high bending dimensional precision. Thus, it has been difficult to fabricate such a complicated configuration comprised of a plurality of linear and curved portions. There is an additional problem of breaking or damaging the dielectric strips
703
,
704
due to a difference in thermal expansion coefficient between the parallel plate conductors
701
,
702
and the dielectric strips
703
,
704
, an impact, and other factors.
Further, it has been difficult to suppress a transmission loss of a high-frequency signal to or below a specified value in any of the NRD guides according the first conventional construction.
Next, a second construction example of the conventional NRD guide is described. The NRD guide of the second construction example is constructed, as disclosed in Japanese Unexamined Patent Publication No. 8-65015, such that a dielectric strip is provided between a pair of parallel plate conductors, two small projections are formed on the dielectric strip, and recesses engageable with the small projections are formed in one of the parallel plate conductors. In the thus constructed NRD guide, the parallel plate conductors and the dielectric strip can be precisely positioned with respect to each other by fitting the small projections into the recesses.
Other construction examples in which the parallel plate conductors and the dielectric strip are precisely positioned with respect to each other include those disclosed in Japanese Unexamined Patent Publication Nos. 6-260824 and 9-64608. Specifically, these publications disclose that a dielectric member is made of a strip section and collars formed on the upper and lower surfaces of the strip section to prevent a displacement of the strip section, and parallel plate conductors are formed by applying plating of, e.g., copper, silver or a silver paste to the upper and lower surfaces of the dielectric member and baking it.
In the NRD guides of this type, resin materials having a relative dielectric constant of 2 to 4 such as Teflon and polystyrene as mentioned above and ceramic materials such as alumina and cordierite are frequently used as the material of the dielectric strips. Since the dielectric strips need to be precisely positioned, the dielectric strips and the parallel plate conductors are adhered by using an epoxy resin or an organic adhesive having a high heat resistance such as a polyimide resin or a BT resin as disclosed in Japanese Unexamined Patent Publication No. 10-163712. In the case that positioning is not sufficiently precise by the above adhesion, the construction disclosed in Japanese Unexamined Patent Publication No. 8-65015 is adopted.
In the second conventional construction example in which the small projections of the dielectric strip are fitted into the recesses of the parallel plate conductor, it is impossible to arrange the dielectric strip unless the positions of the small projections and the recesses agree. Even if the positions of the small projections and the recesses agree, it is difficult to precisely position the dielectric strip if the small projections are too small or the recesses are too large. This disadvantageously increases a transmission loss of a signal in a coupler formed by bringing connecting portions with the respective devices such as diodes, circulators, terminators closer to the dielectric strip.
In the NRD guide in which the dielectric member is comprised of the strip section and the collar portions, it is difficult to process the same with a good dimensional precision, and a separate housing or the like needs to be provided since the parallel plate conductors formed by baking the plating or silver paste have a l
Hayata Kazuki
Hiramatsu Nobuki
Kii Hironori
Okamura Takeshi
Sato Akinori
Hogan & Hartson LLP
Kyocera Corporation
Tran Pablo N.
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