Electrical connectors – Preformed panel circuit arrangement – e.g. – pcb – icm – dip,... – For receiving coaxial connector
Reexamination Certificate
2001-03-06
2003-08-12
Luebke, Renee (Department: 2833)
Electrical connectors
Preformed panel circuit arrangement, e.g., pcb, icm, dip,...
For receiving coaxial connector
C333S260000
Reexamination Certificate
active
06604949
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to microwave connectors. More particularly, the present invention relates to a microwave connector that connects to a microstrip circuit on a carrier and uses a glass bead for hermetic sealing.
BACKGROUND OF THE INVENTION
FIG. 1
illustrates an assembly of typical connector components
1
along with a housing
2
containing a microstrip substrate
10
supported by a carrier
12
.
FIG. 2
shows more details of the connector components
1
and housing
2
.
FIG. 2
also illustrates a typical sparkplug type coaxial connector
18
and connector components
1
assembly. Components carried over from
FIG. 1
to
FIG. 2
are similarly labeled, as will be carried over in subsequent drawings.
The sparkplug type connector
18
includes a center conductor
16
with a female type pin which mates with a male pin
14
supported by the housing
2
. The center conductor
16
of the connector
18
is supported by a glass bead
20
. Surrounding the glass bead
20
is a metal cylindrical outer conducting shell
19
which is threaded like a sparkplug for insertion into a similarly threaded hole
22
in the wall of the package housing
2
.
The center conductor
14
supported by the housing
2
is also supported by the glass bead
6
which is provided in a opening
22
of the housing. The glass bead
6
in the housing is further hermetically sealed using solder provided in the access hole
26
shown. The center conductor
14
extends a short distance onto the microstrip substrate
10
.
The microstrip substrate
10
typically contains MMICs for mounting on the carrier
12
. The carrier
12
is a thin piece of metal, typically ½ to 1 mm thick, which provides the ground for the microstrip substrate
10
, and hence the MMICs on the microstrip substrate
10
. Carriers which can provide grounding at high frequencies become more desirable with the increasing availability of MMIC subsystems. If a number of MMICs are mounted directly onto a housing and one of them fails, the entire assembly must be discarded, as it is generally impossible to remove a fragile MMIC after it has been mounted by soldering directly to the housing without destroying other MMICs in the vicinity. However, a carrier can be mechanically placed in and removed from the housing without destroying the circuit components mounted on it.
Conventionally, the connector components
1
provide for a coax to microstrip transition including electrical transition and impedance matching between the coaxial transmission line of the coaxial connector and the microstrip transmission line connected to the MMICs. As shown in
FIG. 3
, the compensation can include an air gap
40
between the support bead
6
and housing
2
, as well as a controlled air gap
42
between the microstrip substrate and outer conductor formed by the housing
2
. Typical dimensions for the compensation gaps are shown in
FIG. 3
with a center conductor of 0.009″ and a center conductor pin
14
extending beyond the outer conductor 0.010″ onto the microstrip substrate
10
.
As microwave components and subsystems go higher and higher in frequency, the importance of the coax connector becomes more critical. With the advent of multi-function MMIC chips, two factors normally not required at lower frequencies become required at higher frequencies. First hermicity, and second very short ground paths.
Hermicity in microwave packages is traditionally achieved by use of the glass beads. The beads themselves are hermetic and when soldered correctly into a package, the package becomes hermetic. For microwave applications, the areas surrounding the glass bead are critical for good RF performance. The tight tolerance compensation steps become difficult to achieve as the glass-beads get smaller in size at higher frequencies. The process of soldering the glass bead into the housing also becomes more critical and difficult as the beads shrink in size.
With MMICs built on carriers which are mounted on a housing, a long ground path gap
15
typically exists between the carrier
12
and the outer conductor
28
of the coaxial connector
1
joining the microstrip. The long ground path
15
results in poor performance of the coax to microstrip interface.
FIG. 3
illustrates the typical performance of the connector connected to microstrip shown in
FIGS. 1 and 2
.
SUMMARY OF THE INVENTION
In accordance with the present invention, a hermetic glass bead and a grounding lip are incorporated into the connector, effectively eliminating the poor performance due to a long ground path. The glass bead forms both the hermetic seal and the support for the coax center conductor pin. The ground lip is in the required location to provide a short ground path for the connecting microstrip substrate. When the connector and the housing are coupled together, the assembly allows for a signal to efficiently pass through the center conductor pin to the microstrip line with an adequate ground. The user merely has to solder the connector into a very simple hole in the package. There is no need for soldering the glass bead into the connector, which at high frequencies is very difficult due to the small size of the glass bead. All compensation steps can further be incorporated into the connector.
REFERENCES:
patent: 4259684 (1981-03-01), Dean et al.
patent: 4724409 (1988-02-01), Lehman
patent: 5508666 (1996-04-01), Nguyen
patent: 5576675 (1996-11-01), Oldfield
patent: 5696474 (1997-12-01), Spivey et al.
patent: 5856768 (1999-01-01), Hey-Shipton et al.
patent: 5959514 (1999-09-01), Smith et al.
patent: 6154103 (2000-11-01), Scharen et al.
“Why MMICs!”, downloaded from http://www-unix.ecs.umass.edu/~jackson/mmicuse.html on Oct. 2, 2000.
Anritsu Company
Fliesler Dubb Meyer & Lovejoy LLP
Luebke Renee
McCamey Ann
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