1055497-1 Datasheet, PDF (277/320 Pages) Tyco Electronics – RF Coax Products

RF Coax Connectors
Appendix A - Theory and Application (Continued)
Shielded Twisted Pair Cable is used to eliminate inductive
and capacitive coupling. Twisting cancels out inductive
coupling, while the shield eliminates capacitive coupling.
Most applications for this cable are between equipment,
racks and buildings.
Flexible (Braided) Coaxial Cable is by far the most
common type of closed transmission line because of its
flexibility. It is a coaxial cable, meaning that both the signal
and the ground conductors are on the same center axis.
The outer conductor is made from fine braided wire, hence
the name “braided coaxial cable”. This type of cable is
used in practically all applications requiring complete shield-
ing of the center conductor. The effectiveness of the shield-
ing depends upon the weave of the braid and the number
of braid layers. Tyco Electronics manufacturers connec-
tors for cable sizes ranging from less than 1/8 in. diameter,
for low power applications of around 50 watts, to over 1/2
in. diameter for power of 850 watts at 100 MHz and volt-
ages up to 5000. In addition to power handling capabili-
ties, cables are available for high frequency applications,
high and low temperature applications, severe environ-
mental applications and many other specialized uses.
Triaxial Cable is used when higher “shielding” efficiency
characteristics are required in applications similar to those
using shielded twisted pair cable.
Signal
Outer Conductor
Conductors
Insulation
Outer Conductor
Dielectric
Dielectric
Signal
Conductors
Often you will hear the term “shielded cable”. This is very
similar to coaxial cable except the spacing between center
conductor and shield is not carefully controlled during
manufacture, resulting in non-constant impedance.
Semirigid Coaxial Cable uses a solid tubular outer
conductor rather than the braided type, so that all the RF
energy is contained within the cable. One of the draw-
backs of braided cable is that the shielding is not 100%
effective, especially at higher frequencies. This is because
the braided construction can permit small amounts of short
wavelength (high frequency) energy to radiate. Normally
this does not present a problem; however, if a higher
degree of shielding is required, semirigid coaxial cable is
recommended. For applications using frequencies higher
than 30 GHz a miniature semirigid cable is recommended.
Various connectors are available from Tyco Electronics to
terminate these cables.
Ribbon Coaxial Cable is a relatively recent Tyco Electronics
innovation which combines the advantages of both ribbon
cable and coaxial cable. Tyco Electronics currently pro-
vides both the cable and the insulation displacing coaxial
connector to terminate the cable. Each individual coaxial
cable consists of the signal conductor, dielectric, a foil
shield and a drain wire which is in continuous contact with
the foil. The entire assembly is then covered with an outer
insulating jacket. The unique manufacturing feature of this
cable is the precise placement of the drain wires to permit
gang stripping of the outer jacket and foil. The major
advantage of this cable is the speed and ease with which it
can be mass terminated with the Tyco Electronics insulation
displacement technique. They can also be separated into
individual coaxial lines and terminated with standard coax-
ial connectors as required.
Insulation
Dielectric
Middle Conductor
Figure 18
Twin Conductor and Triaxial Cable
-1000
9
8
7
6
5
4
-300
Solid ^Sheath
-200
Triax
-100
-80
Double Braid
-60
-40
Single Copper Braid
-30
-20
-10
.01 GHz
.1 GHz
Figure 19
1 GHz
Shielding Efficiencies
Catalog 1307191
Revised 3-07
www.tycoelectronics.com
Dimensions are in millimeters
and inches unless otherwise
specified. Values in brackets
are standard equivalents.
10 GHz
Dimensions are shown for
reference purposes only.
Specifications subject
to change.
USA: 1-800-522-6752
Canada: 1-905-470-4425
Mexico: 01-800-733-8926
C. America: 52-55-1106-0803
277
South America: 55-11-2103-6000
Hong Kong: 852-2735-1628
Japan: 81-44-844-8013
UK: 44-8706-080-208