Radio Frequency

Radio frequency Radio frequency (RF) is a frequency or rate of oscillation within the range of about 3 Hz to 300 GHz. This range corresponds to frequency of alternating current electrical signals used to produce and detect radio waves. Since most of this range is beyond the vibration rate that most mechanical systems can respond to, RF usually refers to oscillations in electrical circuits.

Contents 1 Special properties of RF electrical signals • 2 Frequencies • 3 See also • 4 External links •

Special properties of RF electrical signals Electrical currents that oscillate at RF have special properties not shared by direct current signals. One such property is the ease with which they can ionize air to create a conductive path through air. This property is exploited by 'high frequency' units used in electric arc welding, although strictly speaking these machines do not typically employ frequencies within the HF band. Another special property is an electromagnetic force that drives the RF current to the surface of conductors, known as the skin effect. Another property is the ability to appear to flow through paths that contain insulating material, like the dielectric insulator of a capacitor. The degree of effect of these properties depends on the frequency of the signals.

Frequencies Name Extremely

Symbol Frequency Wavelength ELF

a 3–30 Hz k 10–

Applications Directly audible when converted to sound

low frequency

100 Mm

(above ~20 Hz), communication with submarines

Super low frequency

SLF

b 30– 300 Hz

j 1–10 Mm

Directly audible when converted to sound, AC power grids (50–60 Hz)

Ultra low frequency

ULF

c 300– 3000 Hz

i 100– 1000 km

Directly audible when converted to sound, communication with mines

Very low frequency

VLF

d 3–30 kHz

h 10– 100 km

Directly audible when converted to sound (below ~20 kHz; or ultrasound otherwise)

Low frequency

LF

e 30– 300 kHz

g 1–10 km

AM broadcasting, navigational beacons, lowFER, amateur radio

Medium frequency

MF

f 300– 3000 kHz

f 100– 1000 m

Navigational beacons, AM broadcasting, amateur radio, maritime and aviation communication

High frequency

HF

g 3– 30 MHz

e 10–100 m

Shortwave, amateur radio, citizens' band radio, skywave propagation

Very high frequency

VHF

h 30– 300 MHz

d 1–10 m

FM broadcasting, amateur radio, broadcast television, aviation, GPR, MRI

Ultra high frequency

UHF

Broadcast television, amateur radio, mobile i 300– telephones, cordless telephones, wireless c 10–100 cm 3000 MHz networking, remote keyless entry for automobiles, microwave ovens, GPR

Super high frequency

SHF

j 3–30 GHz b 1–10 cm

Extremely high frequency

EHF

k 30– 300 GHz

Wireless networking, satellite links, amateur radio, microwave links, satellite television, door openers

Microwave data links, radio astronomy, amateur a 1–10 mm radio, remote sensing, advanced weapons systems, advanced security scanning

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v•d•e

Frequency allocation Plastic Sealing/Welding Technologies Radio waves RF connector Spectrum management Ultrasound RF Switch Matrix – A custom configuration of high frequency switches used in automated test for testing high frequency components and electronic devices

Radio spectrum

E SU V L M H V U SE L LL F FH H F FFFF 33 3330033 00M 00 H 0kH 0G zH H kzM H G zH zH H M zH 3zz3zH z 0330z3 0303303 H 00M 030 zkM H 0G 0 H H kH zG H zzH zM H zG zH zH zz v•d•e

Electromagnetic spectrum

← shorter wavelengths

longer wavelengths → Gamma rays · X-rays · Ultraviolet · Visible · Infrared · Terahertz radiation · Microwave · Radio

Visible (optical) Microwaves Radio Wavelength types

Violet · Blue · Green · Yellow · Orange · Red W band · V band · Q band · Ka band · K band · Ku band · X band · S band · C band · L band EHF · SHF · UHF · VHF · HF · MF · LF · VLF · ULF · SLF · ELF Microwave · Shortwave · Medium wave · Longwave

RF connector N male type RF connector. An RF connector is an electrical connector designed to work at radio frequencies in the multimegahertz range. RF connectors are typically used with coaxial cables and are designed to maintain the shielding that the coaxial design offers. Better models also minimize the change in transmission line impedance at the connection. Mechanically they provide a fastening mechanism (thread, bayonet, braces, push pull) and springs for a low ohmic electric contact while sparing the gold surface thus allowing above 1000 reconnects and reducing the insertion force. Research activity in the area of radio-frequency (RF) circuit design has surged in the last decade in direct response to the enormous market demand for inexpensive, high data rate wireless transceivers.

Contents •

1 Types ○ 1.1 Standard types ○ 1.2 Miniature types ○ 1.3 Sub-miniature types ○ 1.4 Precision types ○ 1.5 Flange connectors

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1.6 Quick-lock connectors

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2 References

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3 External links

Types N right angle direct male connector, solder-type, for semi-rigid .141 cable Standard types •

7/16 DIN connector, a high power 50 Ω connector originally developed by Spinner[1]

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BNC (bayonet Neill-Concelman)

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C connector (Concelman)

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Dezifix connector, hermaphrodite connector used mainly by Rohde & Schwarz

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GR connector (General Radio)

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F connector, used for domestic television installations and domestic satellite LNBs (75 Ω) world wide.

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HN connector, a high voltage version of the N connector

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IEC 169-2 connector, also called Belling Lee connector used throughout Europe and some other countries for domestic television installations and as FM connector for radio. It is standardised in EN 60169-2.

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Motorola connector, standard AM/FM antenna connector used for automotive radios

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Musa connector, a 50 Ω connector used in telecommunications and broadcast video

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NMO mount (new Motorola mount), for removable mobile antennas. Large threaded base for durability in wind.

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N connector (Neill)

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SC connector, screw version of C connector

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TNC connector (threaded Neill-Concelman)

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UHF connector (e.g., PL-259/SO-239). Also referred to as an M-type connector by Japanese manufacturers such as Kenwood

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Twin lead

Miniature types •

Miniature BNC connectors

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Miniature UHF connectors

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DIN 47223 connectors

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U.FL connector

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IPX connector

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SMZ connector - System 43 (BT43 and High Density HD43) for use in DDF

Sub-miniature types •

MMCX connector

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MCX connector

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FME connector

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SMA connector, including variants: ○ 3.5 and 2.92 mm connectors, which cross-mate with SMA, and ○ 2.4, 1.85 and 1.0 mm connectors, which do not cross-mate with SMA

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SMB connector

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SMC connector

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SMP connector

Precision types •

APC-7 connector

Flange connectors •

EIA RF Connectors series of RF flange connectors

Quick-lock connectors •

QMA and QN connector

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QLS connector

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SnapN connector

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Mini-QMA and HPQN

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Antenna socket

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MHV connector, a coaxial connector designed for high voltages

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SHV connector, a safer coaxial connector designed for high voltages

The following audio and video connectors are sometimes used for RF, but are not generally considered to be RF connectors: •

DIN connector (not to be confused with the "7/16 DIN" connector)

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RCA connector (Radio Corporation of America) originally introduced for audio, but now widely used for video as well

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SCART

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List of coaxial connectors

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Concentric twinax connector

RF connectors APC-7 · BNC · C · F · FME · Hirose U.FL · IPX · Motorola · MCX · MMCX · N · QLS · QMA/QN · SMA · SMB · SMC · Twin-lead · TNC · TV aerial plug · UHF / Mini-UHF

Variations and alternate names: 2.9 mm (SMA) · 7 mm · Triax / Triaxial · Twin BNC / Twinax (BNC) · IPEX · MHF · AMC (UFL) · SnapN · RP-TNC · RP-SMA Old or seldom used: EIA · GR · Musa See also: Radio frequency · Radio spectrum · Audio and video connectors · Audio and video interfaces and connectors

Analog video standards RF connector · Composite video · S-Video (Y/C) · Component video (YPbPr • RGB)

RF Switch Matrix An RF/Microwave Switch Matrix is used in test systems, in both design verification and manufacturing test, to route high frequency signals between the device under test (DUT) and the test and measurement equipment. Besides signal routing, the RF/Microwave Switch Matrix may also contain signal conditioning including passive signal conditioning devices, such as attenuators, filters, and directional couplers, as well as active signal conditioning, such as amplification and frequency convertors. Since the signal routing and signal conditioning needs of a test system differ from design to design, RF/Microwave Switch Matrices typically have to be custom designed by the test system engineer or a hired contractor for each new test system. The Switch Matrix is made up of switches and signal conditioners that are mounted together in a mechanical infrastructure or housing. Cables are employed to interconnect the switches and signal conditioners. The switch matrix then employs some type of driver circuit and power supply to power and drive the switches and signal conditioners. The switch matrix uses connectors or fixtures to route the signal paths of the sourcing and measurement equipment to the DUT. The switch matrix is typically located close to DUT in the test system to shorten the signal paths to the DUT thus reducing insertion loss and signal degradation.

Contents • • • • •

1 Benefits of an RF/Microwave Switch Matrix 2 Making It vs Buying It 3 Signal Routing 4 Example Applications 5 Design Challenges

6 External links • 7 References •

Benefits of an RF/Microwave Switch Matrix The purpose of a switch matrix is to move the signal routing and signal conditioning to one central location in the test system versus having it all distributed at various places in the test system. Moving the signal routing and signal conditioning to a single location in the test system has the following advantages: • Calibration plane between the DUT and test equipment becomes smaller and centralized making it easier to characterize. • Switches and signal conditioners have similar power, mounting, and driver requirements so moving them to a single location means you will only need a single power supply and driver circuit to power and control them. • Short signal paths reduce insertion loss and increase signal integrity. • Exact length signal paths are possible to control phase issues. • Simplifies service and support.

Making It vs Buying It Switch matrices present a unique problem to test system designers because the signal conditioning needs, the frequency range, the bandwidth, and power aspects change from application to application. So test and measurement companies cannot provide a one size fits all solution. This leaves test system designers with two choices for their switch matrix design: Create an in-house solution or contract it out. Advantages of creating your switch matrix in-house: • Proprietary concerns can be a big issue especially in the Aerospace Defense industry. Creating a switch matrix in-house makes proprietary concerns a non-issue. • Using spare human resources may be less costly. • Being the first to develop an emerging technology into a finished product can be very profitable for a company. When building a switch matrix inhouse the timely process of shopping around for the right contractor is bypassed. A company is in control of the amount of daily man hours spent developing a switch matrix. • Successive switch matrix designs can be highly leveragable from design to design. The switch driver hardware and software, the mechanical designs,

the power supply, etc. can all be leveraged from design to design with little or no modification. Contracting out advantages: • Company lacks spare human resources. • System integrators (contractors) tend to have more experience and expertise. They can design within tight specs and can handle complicated designs. • System integrators can provide guaranteed work as well as product support.

Signal Routing There are two types of switches typically used in switch matrices: Coaxial Electromechanical Switches and Solid State Switches, also known as electronic switches. Coaxial electromechanical switches can be further divided into two categories based on their architecture, latching relay and non-latching relay. Solid state switches come in three types: PIN diode, FET, and hybrid. The advantages of solid state switches over EM switches include they have much faster switching speed (at least 10,000 times faster), they have an almost infinite life, and they are very stable and repeatable. On the other hand, since solid state switches have nonlinear portions over their frequency range their bandwidth is limited. Also, EM switches provide better insertion loss, VSWR, power handling, and isolation specifications. For these reasons EM switches are used much more often in switch matrix designs.

Example Applications Custom Switch Matrices are used extensively throughout test systems in the wireless and aerospace defense sectors for design verification and manufacturing test. They can range from the simple to the complex. An example of a simple design switch matrix application would be a 1:16 MUX configuration that routes 12 satellite TV feeds to a single spectrum analyzer input that is used to perform signal integrity checks on the satellite feeds. Such a design would require 5 SP4T coaxial EM switches as well as interconnecting coax cable for the signal routing along with a mechanical infrastructure, power supply, and switch driver circuit to mount, power, and operate the switches. An example of a more complex switch matrix is an application that is measuring jitter on multiple high speed serial data buses. The switch matrix inputs the data bus signals then provides the proper switching and signal conditioning for the signals before feeding the signals to test and measurement instruments. This custom switch matrix employed 14 EM switches and a number of different signal conditioners including: power splitters, amplifiers, mixers, filters, and attenuators.

Design Challenges

There are six main challenges when designing a custom RF/Microwave Switch Matrix from beginning to end: 1. Mechanical Design: design of a electrically shielded enclosure or box, internal component mounting brackets, as well as component and cabling layout. 2. RF/Microwave Design: RF/Microwave signal routing and signal conditioning design and testing. A calibration plan for the switch matrix would need to be developed to properly characterize the signal paths. 3. Power and Control Hardware: The power supply and switch driver circuitry will need to be designed and developed. 4. Software Control: A software driver will need to be developed to provide an interface between the control hardware and test system program. 5. Documentation: The whole switch matrix design will have to be documented to support maintenance and possible future design leveraging. 6. Servicing Plan: A servicing plan will need to be developed to ensure the life of the switch matrix lasts as long as the life of the test system. Test equipment manufacturers, such as Agilent Technologies, offer instruments that provide a power supply, driver circuitry, and software drivers that essentially saves a test system designer time and cost by eliminating two of the six switch matrix design challenges: power and control hardware design as well as software driver development. In early 2008 Agilent Technologies introduced a new product concept that aids in custom switch matrix design. The new product offers test system designers a power supply, driver circuitry, and software drivers all wrapped together in a mainframe. The mainframe provides flexible mounting for switches and other components as well as blank front and rear panel that can be easily modified to fit a design need. This new product eliminates 3 of the 6 design challenges: mechanical design, power and control hardware design, and software driver development