Page 249 - belden

TE CH N I C A L INF O RM A T I O N 249

Shielding
Overview

Innovative Leadership
The evolution of technology maintains
steady demand for sophisticated cable Drain Wire Drain Wire
shielding. Belden meets that demand with t o l S t o l S
innovative shielding and shield effectiveness
testing methods to supply you with high
quality, dependable cable. Insulated
Conductor
With the creation of trademarked shield
designs and patented test methods, Belden
has earned a reputation for innovation and
Insulating
leadership that is unequaled in the wire and Film
cable industry. In addition, Belden offers the
Aluminum
broadest line of shielded multi-conductor,
Foil Out Foil In
coaxial and flat cable in the industry.
Figure 1: Foil shield configurations without shorting folds.
Several unique Belden innovations are
utilized across a wide range of shielding
applications: Shorting
Fold
• Beldfoil® — The first aluminum/polyester Drain Wire
foil developed for use as a cable shield. Shorting Drain Wire
Fold
Provides 100% shield coverage for Isolation
optimum protection. Fold
• Duofoil® — Consists of an aluminum-poly-
aluminum laminate wrapped around the
cable’s dielectric core. Provides 100% Aluminum
physical coverage, and improves shield Insulated Aluminum Insulated
reliability and flex life. Insulating Conductor Insulating Conductor
Film Film
Belden also uses a number of innovative
techniques to apply shielding to multi- Figure 2: Foil shield configuration with shorting fold. Figure 3: Foil shield with Z-Fold reduces crosstalk
conductor and paired cables: in multi-pair applications.
• “French Braid” Shields — Belden’s patented • Shorting Fold — Belden uses a shorting • Z-Fold® — Belden improves on the
“French Braid” shield is a double spiral fold technique to maintain metal-to-metal traditional shorting fold by employing
(double serve shield) with the two spirals contact for improved high frequency a Z-Fold designed for use in multi-pair
tied together by one weave. performance. Without the shorting fold, applications to reduce crosstalk. The
a slot is created through which signals Z-Fold (see Figure 3) combines an isolation
can leak and cause interference. and a shorting fold. The shorting fold
(See Figures 1 and 2.) provides metal-to-metal contact while
the isolation fold keeps shields from
shorting to one another in multi-pair,
individually shielded cables.
The use of either a shorting fold or a
Z-Fold increases the foil shield’s range
of effectiveness to higher frequencies.

Belden’s patented “French Braid” shield.
Technical Information

Fo r m o r e i n fo r m at i o n, c o n t a c t Be ld e n Te ch n i ca l S u ppo r t : 1- 8 0 0 - B E L D E N -1 • www. b e l d e n . c o m