Electrical connectors – Including or for use with coaxial cable
Reexamination Certificate
1999-09-15
2002-07-23
Mai, Anh (Department: 2832)
Electrical connectors
Including or for use with coaxial cable
C439S098000, C174S078000, C174S078000, C174S073100
Reexamination Certificate
active
06422900
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to coaxial cable connectors used in communication systems. More particularly, the present invention relates to improved methods and apparatuses for connecting a coaxial cable to a bulk head.
One of the most commonly used transmission lines in the communication industry is the coaxial cable. A coaxial cable is an electrically conducting transmission line configured for carrying signals to and from different types of circuits. More specifically, coaxial cables are configured to have an inner conductor and outer conductor, which are separated by a dielectric insulator and externally covered by an outer insulator. Generally, the inner conductor is configured for carrying the signal and the outer conductor is configured for shielding the inner conductor. For example, the outer conductor prevents energy from radiating from the inner conductor and blocks the pickup of external signals that might interfere with the reception and/or transmission of the signal carried by the inner conductor (e.g. interference).
Because the coaxial cable can prevent interference, it is commonly used in communication systems such as radio, TV, telephony, data and information destined for microwave transmission. In one specific application, the coaxial cable is used to carry signals between an antenna and a transmitter and/or a receiver. Referring initially to
FIG. 1
, an exemplary communication system
10
that uses a coaxial cable to connect an antenna to a transmitter/receiver is shown. Communication system
10
typically includes an antenna
12
(or group of antennas) that is structurally disposed on a tower
14
. By way of example, the antenna
12
may be a “whip” type antenna, a FM antenna, a microwave type antenna, or a panel type antenna. The antenna
12
is operatively coupled to a coaxial cable
16
that runs down the tower
14
to a transmitter and/or receiver (not shown) housed in a transmitter/receiver station
18
.
Furthermore, as the coaxial cable
16
enters the transmitter/receiver station
18
, it is typically coupled to a bulkhead (not shown), which is designed to support the coaxial cable
16
. In some instances, the bulkhead may also be referred to as an entry port. The bulkhead may be configured to be a single point of entry that may be common to many coaxial cables that originate from multiple antennas on the tower (or towers) or it may be configured to support a single coaxial cable. By way of example, there may be as many as twenty antennas on one tower, and as many as sixteen cables (or more) coupled to the bulk head (or entry port) at one time. Following connection to the bulkhead, the coaxial cable is further connected to a specific transmitter or receiver inside the transmitter/station.
When using coaxial cables, especially in communication systems, it is important to use connectors that connect the outer conductor of the coaxial cable to ground. Grounding the outer conductor further helps to dissipate interference from other signals. Therefore, the coaxial cable is typically coupled to a grounded bulkhead. For the most part, the grounded bulk head is formed from a highly conductive material such as brass or copper and coupled to a ground strip that is further coupled to a grounding system (shown in
FIG. 1
as grounding system
20
). The grounding system, which is typically part of the transmitter/receiver equipment, may be useful for addressing issues associated with lightning strikes. Grounding systems are well known in the art and for the sake of brevity will not be discussed in detail here.
Presently, a wide variety of coaxial connectors have been provided for connecting a coaxial cable to a bulkhead. In a typical coaxial connector, the coaxial cable is cut in half (in a direction perpendicular to the cable axis), the exposed cable ends are stripped of insulation and the bare outer conductor is inserted into a pair of coaxial connectors where they can be secured to each of the coaxial connectors. More specifically, a collar is secured to each of the stripped ends and locked in place between a locking nut and each of the coaxial connectors. The pair of coaxial connectors are then coupled to the bulkhead.
Referring to
FIGS. 2 & 3
, a typical coaxial connector system
50
is shown. The coaxial connector system
50
includes a cut coaxial cable
56
. The cut coaxial cable
56
is arranged to include an inner conductor
44
, an outer conductor
46
, an inner insulator
48
(i.e., foam, plastic coil separator, etc.) disposed between the inner and the outer conductor (
44
,
46
), and an outer insulator
49
disposed around the outer conductor
46
. Further, the coaxial connector system
50
includes a pair of cable couplers
52
that are coupled to each of the stripped ends
54
of the cut coaxial cable
56
. The cable couplers
52
are coupled to the stripped ends
54
by securing a collar
58
around the stripped ends
54
of coaxial cable
56
, and thereafter locking the collar
58
between a locking nut
60
and the cable coupler
52
.
The cable couplers
52
are formed from a conductive material, and in electrical contact with the outer conductor
46
when secured to the stripped ends
54
. Furthermore, a conductive pin
62
is disposed between the inner conductors
44
of the cut coaxial cable
56
, in order to electrically connect the broken inner conductor circuit. Following the coupling of the cable couplers to the cut coaxial cable
56
, the cable couplers
52
are disposed together and fastened to a grounded bulk head
64
. In most instances, the fastening of the cable couplers
52
to the grounded bulkhead
64
is implemented with a plurality of bolts
66
.
One problem that has been encountered with the coaxial connector system has been that the coaxial cable is cut in half. As is well known to those skilled in the art, the ability of the coaxial cable to carry a signal is reduced with every cut or break. By way of example, a cut may produce signal reflections that weaken the signal as it is transmitted through the coaxial cable. Signal reflections make it difficult to obtain maximum power transfer through the coaxial cable. Additionally, the cut makes it difficult to achieve proper contact between the conductors of the coaxial cable. Poor connection between mating conductors also leads to weakened signal transmissions.
Furthermore, by cutting the coaxial cable in half, the connection has to be waterproofed to ensure that moisture does not adversely impact the connection. For example, signal loss tends to occur when moisture saturates the conductive path of the conductors. Moisture also tends to corrode the conductors. Referring back to
FIG. 2 & 3
, the prior art overcomes these disadvantages by disposing a shrink wrap tube
68
over the locking nut
60
and the unstripped portion of the cut coaxial cable
56
, and providing an o-ring
70
between the pair of cable couplers
52
. Although
FIG. 2 and 3
show the shrink wrap tube extending only partially over the cable coupler
52
, it should be understood that the shrink wrap tube
68
may be configured with varying lengths and may even extend to the flanged portion of the cable coupler
52
. For the most part, the shrink wrap tube
68
prevents the introduction of moisture at the locking nut/coaxial cable interface and the o-ring
70
prevents the introduction of moisture at the cable coupler/cable coupler interface. However, the additions of the shrink wrap tube and the o-ring further increase the complexity and cost of the connection and may loose their sealing ability over a period of time.
Further still, the coaxial connector system is complex, heavy and difficult to handle. The amount of parts (one for each cut end), e.g., cable coupler, collar, locking nut, conductive pin, o-ring, increases the coaxial connector system assembly time and makes it difficult to install. In fact, it typically takes two people to install the coaxial cable and coaxial connectors to the bulkhead. Correspondingly, the use of complex parts and increased man hours lead to inc
Beyer Weaver & Thomas LLP
HH Tower Group
Lee Kyung S.
Mai Anh
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