1055497-1 Datasheet, PDF (272/320 Pages) Tyco Electronics – RF Coax Products

RF Coax Connectors
Appendix A - Theory and Application
Theory and Application
As a leading manufacturer of RF products, Tyco Electronics
produces a large variety of coaxial connectors. The proper
selection and application of these connectors requires a knowl-
edge of factors not involved in other types of connectors and
terminals. The following paragraphs have been prepared to
improve understanding of the theory behind RF connectors:
Basic RF Theory¹
RF energy travels by electromagnetic waves, and it is pri-
marily the frequency of these waves that we are interested
in. Briefly, if an oscillating voltage source is connected to a
cable, a continuous electromagnetic wave will propagate
along the cable. A sensor placed at some point on the
cable would indicate a varying voltage (E field) as well as a
current and magnetic field (H field) as the wave travels past
it. This is called an electromagnetic wave because both
electric and magnetic fields are varying. The wave shape is
initially determined by the variation of the source with time.
Figure 7 shows the radiant energy spectrum. Visible light,
radio, television, x-rays and Gamma rays are all phenome-
non of electromagnetic waves at different frequencies. This
introduction will treat only those that are generated by an
electrical source and propagated along a physical cable
or other transmission media. That is, frequencies above
zero and up to about 50 gigahertz.
1_{The majority of the technical terms, relative to RF and coaxial cable and}
connectors, used here-in and throughout this catalog are defined in the Glossary
(Appendix G) starting on page 301.
Frequency or
Wavelengths
Designation
Applications
In the following paragraphs we will discuss waves in greater
detail, including the relationship of frequency and wave length,
how pulses are formed and used, how each differs from the
other and the problems involved in their transmission.
Sine Waves
An RF wave is a sine wave, meaning that it smoothly swings
from zero to a positive peak value, then back down past
zero to a negative peak value, then back to zero to com-
plete a 360 electrical degree cycle. The positive and nega-
tive peaks are always equal in amplitude. The two qualities
which characterize this type of wave are amplitude and fre-
quency (f). Figure 8 shows these two characteristics.
Amplitude refers to the peak value attained by the wave and
corresponds to voltage. Frequency refers to the number of
oscillations per second. For example, the sign wave in
Figure 8(B) has completed 12 cycles in one second.
Therefore, we would say that this wave has a frequency of
12 cycles per second or 12 Hertz. The time for one com-
plete cycle is defined as the period (T). The relationship
between the period and frequency is given by the equation:
f = 1 / T in Hertz
Peak
Positive
Amplitude
A
One Cycle
Peak
Negative
Amplitude
0 - 29.9
KHz
VLF
(Very Low
Frequency)
Commercial AC electricity, deep
depth sounders, ultrasonic
grinders, sonic oscillators
30 - 299.9
KHz
LF
(Low sonar
Frequency)
Shallow-to-medium depth sounders
300 - 2999.9
KHz
MF
(Medium
Frequency)
Commercial AM radio broadcasting,
marine radio telephone, direction
finders
3 - 29.9
MHz
HF
(High
Frequency)
Citizen band radio, amateur radio,
international broadcasting
30 - 299.9
MHz
VHF
(Very High
Frequency)
VHF television (Channels 2 thru
13), commercial FM radio
broadcasting, amateur radio, fire
and police radio
300 - 2999.9
MHz
UHF
(Ultra-high
Frequency)
UHF television (Channels 14 thru
83), microwave ovens, aeronautical
radionavigation
3 - 29.9
GHz
SHF
(Super High
Frequency)
Microwave communications, marine
radar, aircraft tracking and
airborne radars
30 - 299.9
GHz
EHF
(Extremely High
Frequency)
Space communications, radio
astronomy
Notes:
1. KHz = Kilohertz (1 thousand cycles per second)
2. MHz = Megahertz (1 million cycles per second)
3. GHz = Gigahertz (1 billion cycles per second)
Figure 7
Radiant Energy Spectrum
B
No. of Cycles
1
1
2
2
3 4 56
3456
7
7
8
8
9
9
10
10
1₁1₁
12
12
1 Second
Figure 8
Typical Sine Wave Characteristics
The wave travels away from the generator at speeds approach-
ing the speed of light. When an electromagnetic wave travels in
a medium other than air or vacuum, the speed for the wave is
reduced by a factor of the square root of the dielectric constant
( ε. The velocity (v) of the propagation of a signal is given by:
v= ^_cε^_
Where c is the speed of light, 3 x 10⁸ m/sec or 1.18 x 10¹⁰
in/sec, and ε is the dielectric constant of the medium.
(See Table 1 for dielectric constants of various materials)
The wavelength of a signal is given by the formula
λ = v/f = ^{_____c_____ _1_._1_8__x_1__01i0nches}
ε x f (GHz) ε x f (GHz)
See Figure 9
272
Catalog 1307191
Revised 3-07
www.tycoelectronics.com
Dimensions are in millimeters
and inches unless otherwise
specified. Values in brackets
are standard equivalents.
Dimensions are shown for
reference purposes only.
Specifications subject
to change.
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