Wave transmission lines and networks – Long line elements and components – Strip type
Reexamination Certificate
2001-02-02
2003-02-04
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Long line elements and components
Strip type
C333S260000, C333S219000
Reexamination Certificate
active
06515561
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a connecting structure and a frequency adjusting method therein, and, more particularly, to improvements in a connecting structure for circuits operating at a microwave or millimeter wave frequency band.
2. Description of Relevant Art
An electrical device is produced by combining various circuits and devices, for example. Practically, circuits are installed in the electrical device by means of forming a printed circuit board for each circuit, placing the printed circuit boards on a mother board through spacers or the like, and connecting each printed circuit board to the circuit on the mother board.
Conventionally, each printed circuit board is connected to the mother board (printed circuit board) or devices with a connecting member of metal, such as a wire or a ribbon, so that conduction is established between the terminals of circuits or the like to be connected by linking both ends of the connecting member to the respective terminals electrically and mechanically by means of soldering or ultrasonics.
However, the conventional connecting structure using the above connecting member has the following problems. That is, when the connection is established with the above connecting member in the range of a microwave or a millimeter wave having a short wavelength, the circuit constant varies in response to the length and shape of the connecting member, and also in response to a quantity of soldering or the connecting position when the connecting member is bonded to the terminals, which causes the transmission state to become unstable.
Also, when the desired circuit characteristics cannot be obtained due to the foregoing causes, characteristic adjusting processes of various kinds have to be carried out by, for example, partially removing the connecting member or soldering or providing an auxiliary member. However, most of the characteristic adjusting processes rely on one's experience and involve a complicated procedure. Therefore, these processes are not suitable for mass-producing products of uniform quality.
In addition, because the terminals and connecting member are closely adhered to each other, if the circuit arrangement or devices need to be changed after manufacturing, the connecting member is cut to separate the connected printed circuit boards, and reconnected to a replaced printed circuit board or the like. This cutting procedure makes the replacement job difficult.
Further, if cuttings from the cut connecting member are not removed completely, the residual cuttings may adversely affect the circuit characteristics. Moreover, heating for adhering the connecting member, or removing the cuttings, may undesirably cause a change in the shape and dimension of the circuit pattern or separation of the same.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above problems, and therefore, has as an object to provide a new connecting structure and a new frequency adjusting method in the connecting structure.
Another object of the present invention is to provide a non-contact connecting structure for high frequency circuits operating at microwave or millimeter wave frequencies, with which a connection between circuit elements can be readily established without requiring high accuracy in assembly and dimension. Also, components can be readily replaced after the connection is established while suppressing a change in the connection state that possibly occurs during replacement. The connecting structure is also stable under temperature-change and capable of protecting devices on the circuit. A further object is to provide a frequency adjusting method in such a connecting structure.
In order to achieve the above and other objects, in a first aspect of the present invention, there is provided a connecting structure for first and second high frequency circuit elements (corresponding to first and second circuit boards
2
and
3
in the embodiment discussed below) each provided with a dielectric substrate having a transmission line (corresponding to strip lines
4
a
and
4
b
in the embodiment) made out of a conductive film on a top surface thereof. The first and second high frequency circuit elements are placed in such a manner as to secure a predetermined gap therebetween. A connecting terminal pattern (corresponding to patch portions
5
a
and
5
b
in the embodiment described below) constituting a resonator is formed continuously with the transmission line on the top surface of the high frequency circuit elements, and a supporting member is placed on a top surface of the connecting terminal pattern formed on the first high frequency circuit element. A parasitic element made of a dielectric material is cantilevered by the supporting member, and a free end side of the parasitic element is placed above the connecting terminal pattern formed on the second high frequency circuit element while securing a predetermined space between the parasitic element and the connecting terminal pattern on the second high frequency circuit element.
The high frequency circuit element referred to herein means literally an element used in a high frequency circuit, and concrete examples include a circuit board such as a printed circuit board, and other devices. Also, the high frequency referred to in the present invention means the frequency of a microwave or a millimeter wave, for example, and may be an even higher frequency.
The experimental results reveal that when the parasitic element is cantilevered by the supporting element as above such that both ends of the parasitic element are overlaid on the two connecting patterns that will be connected, impedance matching can be achieved in a broad band, which results in a satisfactory connection state within in a high frequency range. This is because a high frequency signal is allowed to propagate due to electromagnetic coupling between the connecting terminal patterns (resonators) and parasitic element.
In the case that the circuits forming the circuit elements are connected, or the circuit and device are connected, processing tolerance and assembly tolerance make it quite difficult to complete assembly while securing an exact gap as designed, which causes a gap between the elements to vary. In the present invention, however, by using the parasitic element, the coupling is enhanced and the passing band is broadened, thereby making it possible to maintain a stable transmission state even when the gap varies to some degree.
Further, because a space is formed between at least the free end of the parasitic element and connecting terminal pattern, a capacitor is formed across this space. Thus, even if static electricity or an abnormal potential, such as a surge, is propagated onto the circuit, it is cut at the connecting structure of the present invention, and will not be propagated extensively to the subsequent stages. Moreover, because the second high frequency circuit element and parasitic element are not fixed to each other, replacement at the second high frequency circuit element side is particularly easy.
Furthermore, because the parasitic element is cantilevered, and therefore, is not directly fixed to the second high frequency circuit element, the transmission line (circuit pattern) made out of the conductive film will not be separated due to stress that occurs as a result of heat contraction in response to a temperature change.
The supporting member may have a high dielectric constant. However, according to a second aspect of the present invention, it is preferable that the supporting member is made of a material having a low dielectric constant. The material having a low dielectric constant referred to herein means a material having a dielectric constant lower than that of the dielectric substrate. Besides those generally referred to as the materials having a low dielectric constant, materials having a dialectic constant greater than 1 and not greater than 3 are preferable.
By using the material having a low dielectric constant, loss in th
Arai Hiroyuki
Atsumi Naoki
Izumi Hajime
Tamura Takashi
FDK Corporation
Glenn Kimberly E
Lee Benny
Wenderoth , Lind & Ponack, L.L.P.
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