Wires & Cables
by Udo Koch
Table of Contents
Skin Effect
Proximity Effect
Current Carrying Capacity of Copper Conductors
Amateur Radio is called a “Wireless” hobby, but it still requires wires and cables to interconnect our equipment. If you have a single conductor we call it a wire, but if you have multiple conductors in a common jacket, it is called a cable. There are also cords, which are a special form of cable like a lamp cord or zip-cord where two or three insulated conductors are fused together in parallel. Sometimes the expression cable vs. cord is exchanged loosely and means the same as a “Power Cord” which actually most the time is a cable terminated on one end in a plug for the power outlet. The other end can be some type of detachable connector matching the equipment you power or can be permanently connected to the equipment.
Wires can come as solid wires which have one uniform conductor or stranded wire which have multiple conductors but non isolated from each other in a common isolating jacket. The flexibility of wires depends on how many strands the wire has. Single strand or solid wire are very stiff and not flexible. As more strands a wire has as more flexible it gets. For cables, the flexibility depends additionally on the number of strands also on material and stiffness of the jacket.
Conductors for wires and cables are normally made from copper. However, to save weight and cost they can also be made from aluminum. Aluminum is less conductive (61%) but only 30% of the weight of copper. The big problem with aluminum wire is that over time the aluminum combines chemically with the oxygen in the air and forms a coating on the conductor which has a high resistance to the flow of electricity. Aluminum conductors are also very hard to solder. The usage of copper clad aluminum wire overcomes these problems but still has the advantage of lower weight and cost. However, it also is still less conductive than a pure copper conductor. For harsh environments (like marine applications) copper conductors are often tinned to protect them from corrosion.
A special form of cables used in our hobby are coaxial cables, which come in a variety number of sizes and characteristics. Here too it is important to select the right cable for the right application. We mostly use cable in our hobby with a nominal impedance of 50Ω were cable for over the air TV antennas and cable TV are nominal 75Ω.
Skin Effect
The resistance of a conductor depends on its cross-sectional area; a conductor with a larger area has a lower resistance for a given length. However, at high frequencies, current does not penetrate deeply into conductors; it tends to flow near the surface. This is called the skin effect. Therefore, in a solid conductor like a wire, current tends to flow in a layer at the surface, and less current flows through the material near the center of the wire. Since less of the cross-sectional area of the wire is being used, the resistance of the wire for alternating current (AC) is greater than it is for direct current (DC). The higher the frequency of the current, the smaller the depth to which the current penetrates, and the current is "crowded" into an increasingly smaller cross-sectional area along the surface, so the AC resistance of wire increases with frequency.
The depth to which AC current penetrates in a conductor is determined by a parameter called the skin depth, which is the depth at which the current is reduced to 37% of its surface value. The skin depth decreases with frequency. At low frequencies at which the skin depth is larger than the diameter of the wire, the skin effect is negligible, and the current distribution and resistance are virtually the same as at DC. As the frequency rises and the skin depth gets smaller than the wire diameter, skin effect becomes significant, the current is increasingly concentrated near the surface, and the resistance per unit length of wire increases above its DC value. Examples of skin depth in copper wire at different frequencies:
At 60 Hz, the skin depth of a copper wire is about 7.6 mm (0.30 in).
At 60,000 Hz (60 kHz), the skin depth of copper wire is about 0.25 mm (0.0098 in).
At 6,000,000 Hz (6 MHz) the skin depth of copper wire is about 0.025 mm (0.00098 in).
Round conductors such as wire or cables larger than a few skin depths do not conduct much current near their axis, so the metal located at the central part of the wire is not used effectively.
Proximity effect
In applications where multiple wires carrying the same current lie side-by-side, such as in inductor and transformer windings, a second similar effect called proximity effect causes additional current crowding, resulting in an additional increase in the resistance of the wire with frequency. In two wires running parallel next to each other, with the same alternating current flowing in both wires, the magnetic field of the adjacent wire induces longitudinal eddy currents in the wire which causes the current to be concentrated in a narrow strip on the side adjacent to the other wire. This has a similar effect as the skin effect; the current is crowded into a smaller cross-sectional area of the wire, so the resistance increases.
Current Carrying Capacity of Copper Conductors
Current carrying capacity is defined as the amperage a conductor can carry before melting either the conductor or the insulation.
Heat, caused by an electrical current flowing through a conductor, will determine the amount of current a wire will handle. Theoretically, the amount of current that can be passed through a single bare copper wire can be increased until the heat generated reaches the melting temperature of the copper.
There are many factors which will limit the amount of current that can be passed through a wire. These major determining factors are:
Conductor Size: The larger the circular mil area, the greater the current capacity.
Insulation: The amount of heat generated should never exceed the maximum temperature rating of the insulation material.
Ambient Temperature: The higher the ambient temperature, the less heat required to reach the maximum temperature rating of the insulation.
Conductor Number: Heat dissipation is lessened as the number of individually insulated conductors, bundled together, is increased.
Installation Conditions: Restricting the heat dissipation by installing the conductors in conduit, duct, trays or raceways lessens the current carrying Capacity. This restriction can be alleviated somewhat by using proper ventilation methods, forced air cooling, etc.
In our hobby, especially for low voltage applications like most of our radios are, the allowable voltage drop is most important. Sometimes you want to pick a larger conductor size just to avoid excessive voltage drop.
Taking into account all the variables involved, no simple table of current rating can be developed and used as the final word when designing a system where amperage ratings can become critical. The first table on the next page shows the current required to raise the temperatures of single insulated conductor in free air (30° C ambient) to the limits of various insulation types. The second table on the next page gives a derating factor to be used when the conductors are bundled. These tables should only be used as a guide when attempting to establish current ratings on conductor and cable.
Current carrying capacity of copper wires in Amperes.
Derating Factor for Conductor Bundles
For more details about sizing of wires from a safety standpoint got to: NFPA Electrical Code Ampacity Charts for a free download of charts.
Voltage Drop in Conductors
Voltage drop occurs when electrical current flows through a conductor. As the current flows, the wire has a resistance, which causes the voltage to decrease. The longer the conductor or the larger the current, the greater the voltage drop will be.
If the voltage drop is too high, it can cause the devices and equipment connected to the circuit to malfunction or fail. For example, if the voltage drop is too high in the supply line to a radio, the radio will have a reduced output power or even malfunction which can lead to equipment failure.
For o applications we want to stay below a 0.5V voltage drop at maximum rated current. This would mean 0.25V per conductor in a two-wire feed.
Here are some tables for approximate voltage drop for copper and aluminum conductors. Cupper clad aluminum wire is like pure aluminum wire. The copper clad is normally very thin and doesn’t add much to the conductivity.
Here is a link to an online volage drop calculator:
www.rapidtables.com/calc/wire/voltage-drop-calculator.html
Copper Conductor - Voltage drop per foot and conductor
Wirer Size
5A
10A
15A
20A
25A
30A
35A
28AWG
0.647
1.295
1.942
2.59
3.237
3.885
4.532
24AWG
0.256
0.512
0.768
1.024
1.28
1.536
1.793
22AWG
0.161
0.322
0.483
0.644
0.805
0.966
1.127
20AWG
0.101
0.203
0.304
0.405
0.506
0.608
0.709
18AWG
0.064
0.127
0.191
0.255
0.318
0.382
0.446
16AWG
0.04
0.08
0.12
0.16
0.2
0.24
0.28
14AWG
0.025
0.05
0.076
0.101
0.126
0.151
0.176
12AWG
0.016
0.032
0.048
0.063
0.079
0.095
0.111
10AWG
0.01
0.02
0.03
0.04
0.05
0.06
0.07
8AWG
0.006
0.013
0.019
0.025
0.031
0.038
0.044
Copper Conductor - Voltage drop per 10 foot and conductor
Wirer Size
5A
10A
15A
20A
25A
30A
35A
28AWG
6.474
12.95
19.42
25.9
32.37
38.85
45.32
24AWG
2.561
5.121
7.682
10.24
12.8
15.36
17.93
22AWG
1.61
3.221
4.831
6.442
8.052
9.663
11.27
20AWG
1.013
2.026
3.038
4.051
5.064
6.077
7.09
18AWG
0.637
1.274
1.911
2.548
3.185
3.822
4.459
16AWG
0.401
0.801
1.202
1.602
2.003
2.404
2.804
14AWG
0.252
0.504
0.756
1.008
1.26
1.512
1.764
12AWG
0.158
0.317
0.475
0.634
0.792
0.951
1.109
10AWG
0.1
0.199
0.299
0.399
0.498
0.598
0.698
8AWG
0.063
0.125
0.188
0.251
0.313
0.376
0.439
Aluminum Conductor - Voltage drop per foot and conductor
Wirer Size
5A
10A
15A
20A
25A
30A
35A
28AWG
1.061
2.123
3.184
4.246
5.307
6.369
7.43
24AWG
0.42
0.84
1.26
1.679
2.099
2.519
2.939
22AWG
0.264
0.528
0.792
1.056
1.32
1.584
1.848
20AWG
0.166
0.332
0.498
0.664
0.83
0.996
1.162
18AWG
0.104
0.209
0.313
0.418
0.522
0.627
0.731
16AWG
0.066
0.131
0.197
0.263
0.328
0.394
0.46
14AWG
0.041
0.083
0.124
0.165
0.207
0.248
0.289
12AWG
0.026
0.052
0.078
0.104
0.13
0.156
0.182
10AWG
0.016
0.033
0.049
0.065
0.082
0.098
0.114
8AWG
0.01
0.021
0.031
0.041
0.051
0.062
0.072
Aluminum Conductor - Voltage drop per 10 foot and conductor
Wirer Size
5A
10A
15A
20A
25A
30A
35A
28AWG
10.61
21.23
31.84
42.46
53.07
63.69
74.3
24AWG
4.198
8.397
12.6
16.79
20.99
25.19
29.39
22AWG
2.64
5.281
7.921
10.56
13.2
15.84
18.48
20AWG
1.661
3.321
4.982
6.642
8.303
9.963
11.62
18AWG
1.044
2.089
3.133
4.177
5.222
6.266
7.31
16AWG
0.657
1.314
1.97
2.627
3.284
3.941
4.598
14AWG
0.413
0.826
1.239
1.652
2.065
2.478
2.891
12AWG
0.26
0.52
0.779
1.039
1.299
1.559
1.818
10AWG
0.163
0.327
0.49
0.653
0.817
0.98
1.144
8AWG
0.103
0.205
0.308
0.411
0.514
0.616
0.719
The values are approximate only. They vary for stranded wires and number of strands. These values are also applicable for copper clad aluminum wires.
Coax Cables
Coaxial cable, or coax is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric (insulating material); many coaxial cables also have a protective outer sheath or jacket. The term coaxial refers to the inner conductor and the outer shield sharing a geometric axis.
Coaxial cable is a type of transmission line, used to carry high-frequency electrical signals with low losses. It is used in such applications as telephone trunk lines, broadband internet networking cables, high-speed computer data busses, cable television signals, and connecting radio transmitters and receivers to their antennas. It differs from other shielded cables because the dimensions of the cable and connectors are controlled to give precise, constant conductor spacing, which is needed for it to function efficiently as a transmission line.
One advantage of coaxial over other types of radio transmission line is that in an ideal coaxial cable the electromagnetic field carrying the signal exists only in the space between the inner and outer conductors. This allows coaxial cable runs to be installed next to metal objects such as gutters without the power losses that occur in other types of transmission lines. Coaxial cable also provides protection of the signal from external electromagnetic interference.
Coaxial cable conducts electrical signal using an inner conductor (usually a solid copper, stranded copper, or copper plated steel wire) surrounded by an insulating layer and all enclosed by a shield, typically one to four layers of woven metallic braid and metallic tape. The cable is protected by an outer insulating jacket. Normally, the outside of the shield is kept at ground potential and a signal carrying voltage is applied to the center conductor. When using differential signaling, coaxial cable provides an advantage of equal push-pull currents on the inner conductor and inside of the outer conductor that restrict the signal's electric and magnetic fields to the dielectric, with little leakage outside the shield.[citation needed] Further, electric and magnetic fields outside the cable are largely kept from interfering with signals inside the cable, if unequal currents are filtered out at the receiving end of the line. This property makes coaxial cable a good choice both for carrying weak signals that cannot tolerate interference from the environment, and for stronger electrical signals that must not be allowed to radiate or couple into adjacent structures or circuits. Larger diameter cables and cables with multiple shields have less leakage.
The characteristic impedance of the cable (Z0) is determined by the dielectric constant of the inner insulator and the radii of the inner and outer conductors. In radio frequency systems, where the cable length is comparable to the wavelength of the signals transmitted, a uniform cable characteristic impedance is important to minimize loss. The source and load impedances are chosen to match the impedance of the cable to ensure maximum power transfer and minimum standing wave ratio. Other important properties of coaxial cable include attenuation as a function of frequency, voltage handling capability, and shield quality.
Coaxial cable design choices affect physical size, frequency performance, attenuation, power handling capabilities, flexibility, strength, and cost. The inner conductor might be solid or stranded; stranded is more flexible. To get better high-frequency performance, the inner conductor may be silver-plated. Copper-plated steel wire is often used as an inner conductor for cable used in the cable TV industry.
The insulator surrounding the inner conductor may be solid plastic, foam plastic, or air with spacers supporting the inner wire. The properties of the dielectric insulator determine some of the electrical properties of the cable. A common choice is a solid polyethylene (PE) insulator, used in lower-loss cables. Solid Teflon (PTFE) is also used as an insulator, and exclusively in plenum-rated cables. Some coaxial lines use air (or some other gas) and have spacers to keep the inner conductor from touching the shield.
Many conventional coaxial cables use braided copper wire to form the shield. This allows the cable to be flexible, but it also means there are gaps in the shield layer, and the inner dimension of the shield varies slightly because the braid cannot be flat. Sometimes the braid is silver-plated. For better shield performance, some cables have a double-layer shield.[4] The shield might be just two braids, but it is more common now to have a thin foil shield covered by a wire braid. Some cables may invest in more than two shield layers, such as "quad-shield", which uses four alternating layers of foil and braid. Other shield designs sacrifice flexibility for better performance; some shields are solid metal tubes. Those cables cannot be bent sharply, as the shield will kink, causing losses in the cable. When a foil shield is used a small wire conductor incorporated into the foil makes soldering the shield termination easier
Coaxial cables require an internal structure of an insulating (dielectric) material to maintain the spacing between the center conductor and shield. The dielectric losses increase in this order: Ideal dielectric (no loss), vacuum, air, polytetrafluoroethylene (PTFE), polyethylene foam, and solid polyethylene. An inhomogeneous dielectric need to be compensated by a non-circular conductor to avoid current hot spots.
The insulating jacket can be made from many materials. A common choice is PVC, but some applications may require fire-resistant materials. Outdoor applications may require the jacket to resist ultraviolet light, oxidation, rodent damage, or direct burial. Flooded coaxial cables use a water-blocking gel to protect the cable from water infiltration through minor cuts in the jacket. For internal chassis connections the insulating jacket may be omitted.
Common mode current and radiation
Common mode current occurs when stray currents in the shield flow in the same direction as the current in the center conductor, causing the coax to radiate. They are the opposite of the desired "push-pull" differential currents, where the signal currents on the inner and outer conductor are equal and opposite.
Most of the shield effect in coax results from opposing currents in the center conductor and shield creating opposite magnetic fields that cancel, and thus do not radiate. Since the field is enclosed in the shield coax does not normally radiate. However, it is still possible for a field to form between the shield and other connected objects, such as the antenna the coax feeds. The current formed by the field between the antenna and the coax shield would flow in the same direction as the current in the center conductor, and thus not be canceled. Energy would radiate from the coax itself, affecting the radiation pattern of the antenna. With sufficient power, this could affect sensitive electronics near the cable. A properly placed and properly sized balun can prevent common-mode radiation in coax.
Coax Cable Types and Characteristics
Velocity Factor
The velocity factor (VF),[1] also called wave propagation speed or velocity of propagation (VoP or Pv), of a transmission medium is the ratio of the speed at which a wavefront (of an electromagnetic signal, a radio signal, a light pulse in an optical fiber or a change of the electrical voltage on a copper wire) passes through the medium, to the speed of light in vacuum. For optical signals, the velocity factor is the reciprocal of the refractive index.
The speed of radio signals in vacuum, for example, is the speed of light, and so the velocity factor of a radio wave in vacuum is 1.0 (unity). In electrical cables, the velocity factor mainly depends on the insulating material.
Some typical velocity factors for radio communications cables provided in handbooks and texts are given in the following table:
VF (%)
Transmission line
95–99
Open-wire "Ladder" Line
93
HJ8-50B 3 inch Heliax coaxial cable (air dielectric)
86
RG-8 Belden 7810A coaxial cable (gas-injected foam high-density polyethylene)
83
RG-6 Belden 1189A coaxial cable, RG-11 Belden 1523A coaxial cable
82
RG-8X Belden 9258 coaxial cable (foamed polyethylene dielectric)
80
Belden 9085 twin-lead
77
RG-8/U generic (foamed polyethylene)
66
Belden 8723 twin shielded twisted pair stranded (polypropylene insulator)
66
RG-213 CXP213 (solid polyethylene dielectric)
How to Identify Coaxial Cable Types?
The numbers and letters printed on the cable jacket tell you everything you need to know. The type of cable it is, who manufactured it, rating, and more.
Type
Impedance
(ohms)
Core (mm)
Dielectric
Outside diameter
Shields
Remarks
Max. attenuation, 750 MHz
(dB/100 ft)
Type
VF
(in)
(mm)
(in)
(mm)
RG-56/U
48
1.4859
0.308
7.82
Dual braid shielded
Rated to 8000 volts, rubber dielectric
AVA5-50
50
9.45
FPE
0.88
0.95
24.1
1.000
25.4
corrugated copper
Heliax Cellflex low-loss semi-flexible
0.98
AVA7-50
50
18.6
FPE
0.92
1.75
44.5
1.825
46.4
corrugated copper
Heliax Cellflex low-loss semi-flexible
0.58
H155
50
1.41
(19×0.28)
PF
0.79
0.0984
2.5
0.2126
5.4
Double
Lower loss at high frequency for radiocommunication and amateur radio
H500
50
2.5
PF
0.81
0.1772
4.5
0.386
9.8
Double
Low loss at high frequency for radiocommunication and amateur radio, 4.45 @ 1000 MHz
4.45]
HCA214-50J
50
22.7
Air
0.95
1.96
49.9
2.37
60.2
corrugated copper
Semi-flexible hardline
0.50
HCA300-50J
50
29.3
Air
0.96
2.50
63.5
2.99
76.0
corrugated copper
Semi-flexible hardline
0.39
HCA400-50J
50
34.8
Air
0.96
2.96
75.3
3.56
90.5
corrugated copper
Semi-flexible hardline
0.33
HCA495-50J
50
45.0
Air
0.97
3.86
98.1
4.53
115.1
corrugated copper
Semi-flexible hardline
0.25
HCA550-50J
50
58.0
Air
0.96
5.00
127.1
5.79
147.1
corrugated copper
Semi-flexible hardline
0.20
HCA618-50J
50
67.0
Air
0.97
5.78
147.0
6.65
169
corrugated copper
Semi-flexible hardline
0.17
HCA800-50J
50
88.5
Air
0.97
7.67
195.0
8.78
223.0
corrugated copper
Semi-flexible hardline
650 MHz max.
HCA900-50T
50
99.4
Air
0.98
8.53
216.7
9.75
247.7
corrugated aluminum
Semi-flexible hardline
560 MHz max.
LDF4-50A[5]
50
4.83
FPE
0.88
0.51
12.96
0.55
13.97
corrugated copper
Heliax Cellflex low-loss semi-flexible
1.90
LMR-100
50
0.46
PE
0.66
0.0417
1.06
0.110
2.79
Double
Low loss communications, 1.36 dB/meter @ 2.4 GHz
20.7
LMR-195
50
0.94
PF
0.80
0.073
1.85
0.195
4.95
Double
Low loss communications, 0.620 dB/meter @ 2.4 GHz
10.1
LMR-200
HDF-200
CFD-200
50
1.12
PF
0.83
0.116
2.95
0.195
4.95
Double
Low-loss communications, 0.554 dB/meter @ 2.4 GHz
9.0
LMR-240
EMR-240
50
1.42
PF
0.84
0.150
3.81
0.240
6.1
Double
Amateur radio, low-loss replacement for RG-8X
6.9
LMR-300
50
1.78
PF
0.82
0.190
4.83
0.300
7.62
Foil, Braid
Low-loss communications
5.5
LMR-400
HDF-400
CFD-400
EMR-400
50
2.74
PF
0.85
0.285
7.24
0.405
10.29
Double
Low-loss communications, 0.223 dB/meter @ 2.4 GHz, Core material: Cu-clad Al
3.5
LMR-500
50
3.61
PF
0.86
0.370
9.4
0.500
12.7
Double
Low-loss communications, Core material: Cu-clad Al
2.8
LMR-600
50
4.47
PF
0.87
0.455
11.56
0.590
14.99
Double
Low-loss communications, 0.144 dB/meter @ 2.4 GHz, Core material: Cu-clad Al
2.3
LMR-900
50
6.65
PF
0.87
0.680
17.27
0.870
22.10
Double
Low-loss communications, 0.098 dB/meter @ 2.4 GHz, Core material: BC tube
1.5
LMR-1200
50
8.86
PF
0.88
0.920
23.37
1.200
30.48
Double
Low-loss communications, 0.075 dB/meter @ 2.4 GHz, Core material: BC tube
1.3
LMR-1700
50
13.39
PF
0.89
1.350
34.29
1.670
42.42
Double
Low-loss communications, 0.056 dB/meter @ 2.4 GHz, Core material: BC tube
0.8
RG-8/U
50
2.17
PE
0.285
7.2
0.405
10.3
Amateur radio; Thicknet (10BASE5) is similar
5.97
RG-8X
50
1.47
PF
0.82
0.155
3.9
0.242
6.1
Single
A thinner version, with some of the electrical characteristics of RG-8U in a diameter similar to RG-59.
10.95
RG-58/U
50
0.81
PE
0.66
0.116
2.9
0.195
5.0
Single
Used for radiocommunication and amateur radio, thin Ethernet (10BASE2) and NIM electronics, Loss 1.056 dB/m @ 2.4 GHz. Common.
13.10
RG-60/U
50
1.024
PE
0.425
10.8
Single
Used for high-definition cable TV and high-speed cable Internet.
RG-142/U
50
0.94
PTFE
0.116
2.95
0.195
4.95
Double braid
Used for test equipment
9.6
RG-174/U
50
0.5
(7×0.16)
PE
0.66
0.059
1.5
0.100
2.55
Single
Common for Wi-Fi pigtails: more flexible but higher loss than RG58; used with LEMO 00 connectors in NIM electronics.
23.57
RG-178/U
50
0.31
(7×0.1)
PTFE
0.69
0.033
0.84
0.071
1.8
Single
Used for high-frequency signal transmission. 42.7 @ 900 MHz, Core material: Ag-plated Cu-clad Steel
42.7
RG-188A/U
50
0.5
(7×0.16)
PTFE
0.70
0.06
1.52
0.1
2.54
Single
26.2 @ 1000 MHz, Core material: Ag-plated Cu-clad steel
26.2
RG-213/U
50
2.26
(7×0.75)
PE
0.66
0.285
7.2
0.405
10.3
Single
For radiocommunication and amateur radio, EMC test antenna cables. Typically lower loss than RG58. Common.
5.98
RG-214/U
50
2.26
(7×0.75)
PE
0.66
0.285
7.2
0.425
10.8
Double
Used for high-frequency signal transmission.
6.7
RG-218
50
4.963
PE
0.66
0.660 (0.680?)
16.76 (17.27?)
0.870
22
Single
Large diameter, not very flexible, low-loss (2.5 dB/100 ft @ 400 MHz), 11 kV dielectric withstand.
2.83
RG-223/U
50
0.88
PE
0.66
0.0815
2.07
0.212
5.4
Double
Silver-plated shields.
11.46
RG-316/U
50
0.51
(7×0.17)
PTFE
0.695
0.060
1.5
0.098
2.6
Single
Used with LEMO 00 connectors in NIM electronics
22.45
RG-400/U
50
1.0
(19×0.20)
PTFE
2.95
4.95
Double
12.57
RG-402/U
50
0.93
PTFE
3.0
0.141
3.58
Single silver-plated copper
Semi-rigid, 0.91 dB/m@5 GHz
27.7
RG-405/U
50
0.51
PTFE
1.68
0.0865
2.20
Single silver-plated copper-clad steel
Semi-rigid, 1.51 dB/m@5 GHz
46.0
RG-9/U
51
PE
0.420
10.7
3C-2V
75
0.50
PE
0.85
3.0
5.4
Single
Used to carry television, video observation systems, and other. PVC jacket.
5C-2V
75
0.80
PE
0.82±0.02
0.181
4.6
0.256
6.5
Double
Used for interior lines for monitoring system, CCTV feeder lines, wiring between the camera and control unit and video signal transmission. PVC jacket.
QR-320
75
1.80
PF
0.395
10.03
Single
Low-loss line, which replaced RG-11 in most applications
3.34
QR-540
75
3.15
PF
0.610
15.49
Single
Low-loss hard line
1.85
QR-715
75
4.22
PF
0.785
19.94
Single
Low-loss hard line
1.49
QR-860
75
5.16
PF
0.960
24.38
Single
Low-loss hard line
1.24
QR-1125
75
6.68
PF
1.225
31.12
Single
Low-loss hard line
1.01
RG-6/U
75
1.024
PF
0.75
0.185
4.7
0.270
6.86
Double
Low loss at high frequency for cable television, satellite television and cable modems
5.65
RG-6/UQ
75
1.024
PF
0.75
0.185
4.7
0.298
7.57
Quad
This is "quad shield RG-6". It has four layers of shielding; regular RG-6 has only one or two
5.65
RG-7
75
1.30
PF
0.225
5.72
0.320
8.13
Double
Low loss at high frequency for cable television, satellite television and cable modems
4.57
RG-11/U
75
1.63
PE
0.66–0.85
0.285
7.2
0.412
10.5
Dual/triple/quad
Low loss at high frequency for cable and satellite television. Used for long drops and underground conduit, like RG7 but generally lower loss.
3.65
RG-59/U
75
0.64
PE
0.66
0.146
3.7
0.242
6.1
Single
Used to carry baseband video in closed-circuit television, previously used for cable television. In general, it has poor shielding but will carry an HQ HD signal or video over short distances.
9.71
RG-59A/U
75
0.762
PF
0.78
0.146
3.7
0.242
6.1
Single
Similar physical characteristics as RG-59 and RG-59/U, but with a higher velocity factor. 8.9@700 MHz
8.9
RG-179/U
75
0.31
(7×0.1)
PTFE
0.67
0.063
1.6
0.098
2.5
Single
VGA RGBHV, Core material: Ag-plated Cu
RG-62/U
92
PF
0.84
0.242
6.1
Single
Used for ARCNET and automotive radio antennas.
RG-62A
93
ASP
0.242
6.1
Single
Used for NIM electronics
RG-180B/U
95
0.31
PTFE
0.102
2.59
0.145
3.68
Single silver-covered copper
VGA RGBHV, Core material: Ag-plated Cu-clad steel
RG-195
95
0.305
PTFE
0.102
2.59
0.145
3.68
Single
PTFE jacket suitable for direct burial, Core material: Ag-plated Cu-clad steel
RG-63
125
1.2
PE
0.405
10.29
Double braid
Used for aerospace
4.6
RG Coax Cables
RG, short for Radio Guide, is the original military specification for coaxial cables. The RG number refers to the cable's diameter. However, measurements do vary. Generally, a higher RG numbers means a thinner central conductor, and vice versa.
LMR® Coax Cable
LMR® is the newer generation of RF coaxial cables. They provide greater flexibility, ease of installation, and lower cost. They're used as transmission lines for antennas on missiles, airplanes, satellites, and communications. The LMR ® number is a rough estimate of the cables thickness.
Coax Connectors
BNC
BNC Coaxial Cable Bayonet Neill-Concelman (BNC) coaxial cable connectors are one of the most commonly used connector types. They feature a twist and snap bayonet connection design that requires a quarter-turn to form a connection.
Key advantages of BNC connectors include:
Simple design. They have the simplest design of all coax cable connectors.
Easy connection. They do not require any tools.
Small accidental disconnection risk. They lock the connection in place to prevent accidental disconnection caused by vibrations or other movements.
Some of the disadvantages include:
Limited frequency range. They have a frequency range limited to DC-4 GHz.
High susceptibility to variations. They can experience variations in resistance and outer sleeve connection when exposed to mechanical vibrations.
Typical applications include commercial audio/video transmission systems and RF equipment (e.g., frequency generators, small radios, network analyzers, and oscilloscopes).
TNC
TNC Coaxial Cable Threaded Neill-Concelman (TNC) connectors are a miniature threaded variation of BNC connectors. However, they are waterproof and more rugged.
Key advantages of TNC connectors include:
High frequency capacities. They can operate with frequencies up to 11 GHz.
High mating cycle life. They can be used for up to and exceeding 500 cycles.
Low susceptibility to variations. They are less likely to experience variations in resistance and outer sleeve connection when exposed to mechanical vibrations.
Some of the disadvantages include:
Large size, heavy weight. They are heavier and larger than SMA connectors.
Specific attachment requirements. They require a specific coaxial cable form.
Typical applications include UHF and SHF Radio connections and antennas.
UHF
The UHF connector is the name for a threaded RF connector. They are also sometimes called PL-259 connectors. The connector design was invented in the 1930s for use in the radio industry and is a shielded form of the "banana plug". It is a widely used standard connector for HF transmission lines on full-sized radio equipment, with BNC connectors predominating for smaller, hand-held equipment.
The name "UHF" is a source of confusion, since the name of the connectors did not change when the frequency ranges were renamed. The design was named during an era when "UHF" meant frequencies over 30 MHz. Today, Ultra high frequency (UHF) instead refers to frequencies between 300 MHz and 3 GHz[a] and the range of frequencies formerly known as UHF is now called "VHF".
Unlike modern connector designs that replaced it, no active specification or standard exists to govern the mechanical and electrical characteristics of the so-called "UHF" connector system making it effectively a deprecated design with no guarantee for suitability to an electrical or mechanical purpose. Evidence of inconsistency exists. Testing reveals post WWII connectors designs, such as N connector and BNC connector are electrically superior to the 'UHF' connector for modern UHF frequencies.
UHF connectors have a non-constant impedance. For this reason, UHF connectors are generally usable through HF and the lower portion of what is now known as the VHF frequency range. Despite the name, the UHF connector is rarely used in commercial applications for today's UHF frequencies, as the non-constant impedance creates measurable electrical signal reflections above 100 MHz.
Virtually all of the impedance bump and loss is in the UHF female. A typical SO-239 UHF female, properly hooded, has an impedance bump of about 35 ohms. The length of the bump is typically 1⁄2 inch, where the female pin flares to fit over the male pin. This bump can be mitigated by using a honeycomb dielectric in the female pin area.
Some samples of UHF connectors can handle RF peak power levels well over one kilowatt based on the voltage rating of 500 Volts peak. In practice, some UHF connector products will handle over 4 kV peak voltage. Manufacturers typically test UHF jumpers in the 3-5 kV range. UHF connectors are standard on HF amateur amplifiers rated at 1500+ Watts output.
In practice, voltage limit is set by the air gap between center and shield. The center pin diameter and contact area is large enough that pin heating is not an issue. UHF connectors are generally limited by cable heating rather than connector failure.
UHF connectors are not weatherproof and need to be protected if used outdoors.
N Connector
The N connector (also, type-N connector) is a threaded, weatherproof, medium-size RF connector used to join coaxial cables. It was one of the first connectors capable of carrying microwave-frequency signals and was invented in the 1940s by Paul Neill of Bell Labs, after whom the connector is named.
The interface specifications for the N and many other connectors are referenced in MIL-STD-348. Originally, the connector was designed to carry signals at frequencies up to 1 GHz in military applications, but today's common Type N easily handles frequencies up to 11 GHz. More recent precision enhancements to the design by Julius Botka at Hewlett Packard have pushed this to 18 GHz. The male connector is hand-tightened (though versions with a hex nut are also available) and has an air gap between the center and outer conductors. The coupling has a 5⁄8-24 UNEF thread.
The N connector follows MIL-STD-348, a standard defined by the US military, and comes in 50 Ohm and 75 Ohm versions. The 50 Ohm version is widely used in the infrastructure of land mobile, wireless data, paging and cellular systems. The 75 Ohm version is primarily used in the infrastructure of cable television systems. Connecting these two different types of connectors to each other can lead to damage, and/or intermittent operation due to the difference in diameter of the center pin.
Unfortunately, many type N connectors are not labeled, and it can be difficult to prevent this situation in a mixed impedance environment. The situation is further complicated by some makers of 75 Ohm sockets designing them with enough spring yield to accept the larger 50 Ohm pin without irreversible damage, while others do not. In general, a 50 Ohm socket is not damaged by a 75 Ohm pin, but the loose fit means the contact quality is not guaranteed; this can cause poor or intermittent operation, with the thin 75 Ohm male pin only barely mating with the larger 50 Ohm socket in the female.
The 50 Ohm type N connector is favored in microwave applications and microwave instrumentation, such as spectrum analyzers. 50 Ω N connectors are also commonly used on amateur radio devices (e.g., transceivers) operating in UHF bands.
SMA
SMA Coaxial Cable Subminiature Version A (SMA) connectors are 50 Ω connectors. They are available in several formats, including male vs. female, straight-through vs. right-angled, and more.
Key advantages of SMA connectors include:
Small size, light weight. They are smaller and lighter than TNC connectors, making them suitable for applications where size and weight are a concern.
High frequency capacities. They can operate with frequencies up to 18 GHz.
Some of the disadvantages include:
Less robustness. They are less suitable for use in harsh environments than larger connectors.
Unsuitable for frequent connection/disconnection. They are not designed for applications that require frequent connection and disconnection.
Typical applications include microwave systems, telecommunications equipment, and Wi-Fi antennas.
7/16 DIN
7-16 DIN Coaxial Cable7/16 DIN (Deutsches Institut für Normung) connectors have a threaded design. They are typically used for high-wattage transmissions.
Key advantages of 7/16 DIN connectors include:
High intermodulation rejection. They offer higher intermodulation rejection than BNC or N connectors.
High power capacities. They handle higher power levels than most other connectors.
Some of the disadvantages include:
Harder connection/disconnection requirements. They need a wrench for connection and disconnection.
Incongruous with US standards. They are generally used in Europe rather than the United States.
Typical applications are base stations, broadcast communication systems, and other situations involving multiple transmissions.
QMA
QMA Coaxial CableQMA connectors are similar to SMA connectors. However, they have a snap-lock design that allows for faster and easier connection/disconnection and 360° rotational capabilities after connection that allows for better installation flexibility.
Other key advantages of QMA connectors include:
High power capacities. They can handle higher power levels than some of the other connector types.
High frequency capacities. They can operate with frequencies up to 18 GHz.
Their primary disadvantage is the lack of waterproofing. They are not suitable for use in environments where exposure to moisture is expected. However, they are ideal for use in industrial and communications applications that require the maintenance of the shielding barrier.
MCX
MCX Coaxial CableMicro coaxial (MCX) connectors are small form-factor connectors. They are designed for use in applications with size or space limitations.
Key advantages of MCX connectors include:
Similar to SMB connectors but are 30% smaller.
Easy installation. They have a Snap-on coupling design that makes installation simple and quick.
Some of the disadvantages include:
Limited frequency range. They have a frequency range limited to DC-6 GHz.
Variable sizes. They can vary in size depending on the manufacturer.
Typical applications include digital cellular systems, global positioning systems (GPS) devices, RF hardware, and TV tuner cards.