Wave transmission lines and networks – Long line elements and components – Strip type
Reexamination Certificate
1999-05-28
2002-03-12
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Long line elements and components
Strip type
C333S260000, C257S664000, C257S728000
Reexamination Certificate
active
06356173
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a high-frequency module on which are mounted a plurality of high-frequency devices that are operated by high-frequency signals of from a microwave band to a millimeter wave band. More specifically, the invention relates to a high-frequency module capable of transmitting signals among the high-frequency devices without deteriorating the characteristics of high-frequency signals.
2. Description of the Prior Art
In the conventional high-frequency packages mounting high-frequency devices that are operated by high-frequency signals of microwaves or millimeter waves, high-frequency devices are contained in the cavities hermetically closed by walls or closures connected to the surface of a dielectric substrate, and signal transmission lines are electrically connected to the high-frequency devices. The signal transmission lines are electrically connected to signal transmission lines formed on an external circuit board such as mother board, so that high-frequency signals are input to, and output from, the high-frequency devices.
FIG. 11A
illustrates a general structure of such a high-frequency module, wherein cavities
43
,
43
′ are formed on the surface of a dielectric board
41
and are air-tightly closed by closures
42
,
42
′. High-frequency devices
44
,
44
′ are mounted in the cavities
43
,
43
′. On the surface of the dielectric board
41
in the cavities are formed high-frequency signal transmission lines
45
,
45
′ such as strip lines connected to the high-frequency devices
44
,
44
′. The transmission lines
45
,
45
′ are connected, through connection conductors
48
such as wires or ribbons to a conductor layer
47
which is insulated by an insulating block
46
formed at the ends of the closures
42
,
42
′. A portion of the conductor layer
47
is connected, through the connection conductor
48
, to a transmission line formed on the surface of the dielectric board
41
on the outside of the cavity. That is, the input and output of high-frequency signals to and from the high-frequency devices
44
,
44
′ from the external side and the input and output of high-frequency signals between the high-frequency devices
44
,
44
′, are accomplished through the conductor layer
47
and the transmission lines
45
,
45
′.
There have further been proposed high-frequency modules of structures shown in
FIGS. 11B and 11C
.
In the high-frequency module of
FIG. 11B
, for example, a signal transmission line
49
is formed in a dielectric board
41
and is electrically connected to transmission lines
45
,
45
′ that are connected to high-frequency devices
44
,
44
′ via a through-hole conductor
50
. That is, the input and output of high-frequency signals between the high-frequency devices
44
,
44
′, or the input and output of high-frequency signals to and from the high-frequency devices
44
,
44
′ from the external side, is accomplished through the signal transmission line
49
and the through-hole conductor
50
.
The high-frequency module of
FIG. 11C
has been proposed in Japanese Unexamined Patent Publication (Kokai) No. 263887/1995. In this module, each high-frequency device is independently and electromagnetically sealed by an electrically conducting closure, a metal plate
51
is provided on the back surface of the dielectric board, and a dielectric layer is laminated on the back surface of the metal plate
51
. A through-hole is formed penetrating from the front surface of the dielectric board through up to the dielectric layer of the back surface of the metal plate
51
. In the through-hole, there are provided through-hole conductors
52
,
52
′ connected to the input/output terminals of the high-frequency devices on the side of the dielectric board, and through-hole conductors
53
,
53
′ on the back surface of the metal plate
51
on the side of the dielectric layer, the through-hole conductors being connected together through coaxial transmission passages
54
,
54
′ formed in the through-hole of the metal plate
51
. The through-hole conductors
53
,
53
′ on the side of the dielectric layer are further electrically connected to each other through a connection line
55
formed in the dielectric layer. That is, in this module, the high-frequency signals are input and output between the high-frequency devices through the coaxial transmission passages formed in the through-hole.
In the high-frequency module on which a plurality of high-frequency devices are mounted, it is basically requested that the high-frequency signals are input and output among the high-frequency devices without deteriorating the transmission characteristics of high-frequency signals and that the module is easily fabricated. However, the high-frequency modules of the structures shown in
FIGS. 11A
to
11
C are not capable of satisfying such requirements to a sufficient degree.
In the high-frequency module of
FIG. 11A
, for example, the signal transmission line is transformed from a microstrip line into a strip line at a moment when a high-frequency signal passes through the conductor layer
47
and the walls of the closures
42
,
42
′. In order to accomplish the impedance matching, therefore, the width of the signal transmission line must be narrowed. As a result, the reflection loss or the radiation loss easily occurs when the signal passes through the walls of the closures
42
,
42
′ causing the transmission characteristics of high-frequency signals to be deteriorated. To draw the signal transmission lines
45
,
45
′ out of the cavities
43
,
43
′, furthermore, the closures
42
,
42
′ must be provided with dielectric members (insulating blocks
46
) at the lower ends thereof (at portions where the conductor layer
47
passes through). Therefore, this module is complex in the structure driving up the cost of production.
In the high-frequency module of
FIG. 11B
, on the other hand, the high-frequency signals are input and output via the through-hole conductor
50
; i.e., the signal transmission passage does not pass through the walls of the closures, and transmission characteristics of the signals are deteriorated little. In this case, however, the signal transmission passage is folded at portions where the signal transmission line
49
and the through-hole conductor
50
are connected together. When the frequency of signals exceeds 40 GHz, therefore, the transmission loss increases abruptly at the folded portions, making it difficult to transmit high-frequency signals of a frequency higher than 40 GHz.
In the high-frequency module of
FIG. 11C
, too, high-frequency signals are input and output through the coaxial lines
54
,
54
′ provided in the through-hole, making it possible to decrease the transmission loss for the high-frequency signals. It is, however, difficult to form coaxial lines in the through-hole and, besides, reliability is low at the connection portions between the through-hole conductor and the coaxial lines.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a high-frequency module in which a plurality of high-frequency devices are mounted on the surface of a dielectric board and are individually and electromagnetically sealed, featuring a small transmission loss in transmitting signals among the high-frequency devices, and having a simple structure that is easy to fabricate and a small size yet maintaining high reliability.
According to the present invention, there is provided a high-frequency module comprising:
a dielectric board;
a first cavity and a second cavity closed by closures joined to one surface of said dielectric board, the cavities being independent from each other;
high-frequency devices mounted on the surface of said dielectric board at positions in said first cavity and in said second cavity;
internal high-frequency signal transmission lines arranged on the surface of said dielectric
Ishida Masanobu
Kitazawa Kenji
Koriyama Shin-ichi
Kubo Takanori
Minamiue Hidehiro
Hogan & Hartson L.L.P.
Kyocera Corporation
Lee Benny
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