Circulators and isolators are very handy (and necessary) devices for use when it is essential to keep RF signal flow in one direction only. Think of them loosely as a steering diode array that directs energy from one port to a specific other port (or ports). Circulators and isolators (an isolator is basically a circulator with the third port terminated in the characteristic impedance) are fundamentally 3-port devices with 120° between ports. Ferrites with special properties (known only to the sworn circulator designer brotherhood) affect the directional control. Here is a brief circulator application note from MECA Electronics.
One important thing to keep in mind is that specified values for isolation are only guaranteed at 50+j0 ohms, or whatever the characteristic impedance of the attenuator model happens to be (50 and 75 ohms most common). The farther away from the characteristic impedance the connected ports are, the farther from the spec the isolation value will be.
AFT Microwave | +49 7191 9659 0 | Germany
Microwave components including circulators, isolators, waveguide and coaxial components, phase shifters, ferrites, thin film technology.
Advanced Technical Materials (ATM) | 631-289-0363 | Patchogue, NY
Attenuators, bias tees, coaxial cables, couplers, DC blocks, isolators, circulators, line stretchers, noise sources, phase shifters, power dividers/combiners, switches, terminations, waveguide, adapters, horn antenna.
Aerotek Company | 662-332-5035, 311-4448 | Thailand
Coaxial, drop-in, lump, drop-in lump, flange mount circulators & isolators, 88 MHz - 18 GHz.
Cernex | 408-541-9226 | Sunnyvale, CA
Amplifiers, antennas, couplers, isolators, circulators, filters, diplexers, oscillators, noise sources, switches, phase shifters, transition & adapters, mixers, waveguide products, attenuators, terminations, detectors, subsystems.
Channel Microwave | 805-482-7280 | Camarillo, CA
Coaxial and waveguide isolators, circulators, ISO-adapters, integrated assemblies, filters, terminations.
Charter Engineering | 727-549-8999 | Largo, FL
Electromechanical switches, attenuators, isolators, terminations, circulators, power dividers, couplers.
Corry Micronics | 724-940-7556 | Corry, PA
Dielectric resonators, bandpass filters, LC filters, VCOs, PLLs, patch antennas, power dividers, connectorized lumped element power dividers, directional couplers, isolators/circulators, high power hybrids, diplexers & multiplexers, attenuators, switches, cavity filters, waveguides, standard gain horn antennas.
DiTom Microwave | 559-255-7045 | Fresno, CA
Connectorized single and dual junction ferrite isolators and circulators for the space and defense markets. COTS and Hi-Reliability products available covering 700 MHz to 31 GHz.
Dorado International | 206-574-0900 | Seattle, WA
Planar, horn, 8.2 GHz to 110 GHz antennas, waveguide isolators & circulators, switches, adapters, connectors.
EM Design, LLC | 541-878-3927 | Shady Cove, OR
Specializes in the design and fabrication of RF and microwave components, systems and sub-systems including antennas, antenna polarizers, circulators, isolators, waveguide loads, coaxial loads, microwave pulse compressors, waveguide windows, waveguide seals, waveguide shorts, waveguide couplers and microwave heating.
EMR Corporation | 800-796-2875 | Phoenix, AZ
RF peripherals devices from 30 MHz to 2.8 GHz. Design, manufacture and systems' engineering for RF isolators, amplifiers & BDAs, filters - band pass & band reject, mobile & base station duplexers, combiners - cavity ferrite & hybrid ferrite, RX multicouplers and accessories including LNAs.
Ferrite | 603-881-5234 | Hudson, NH
Circulators, isolators, transmitters.
Filtel | 450-455-6082 | Canada
Couplers, power dividers, isolators, coaxial & waveguide circulators.
Innertron | +82-32-816-1456 | Incheon-City, Korea
A wide selection of RF & microwave components as well as power dividers, power splitters, arrestors, bias-Ts, attenuators, terminations, directional couplers which cover the frequency range from DC to 18 GHz. Waveguide filters, diplexer, adaptor, couplers up to 40 GHz, custom designs are available to support applications for the military and commercial industries.
Instruments for Industry (IFI) | 631-467-8400 | Ronkonkoma, NY
Amplifier configurations such as tetrode tubes, TWTs, klystrons, and solid state devices. Standard horn antennas and TEM cells.
Kete Microwave Electronics | +86-595-22597735 | China
Ferrite RF isolator & circulators, high power RF resistors & terminations, fixed & variable/step attenuators, multilayer High-Q chip ceramic& feedthrough capacitor (EMI filters), directional couplers, power dividers / combiners, 3dB hybrid couplers.
JQL Electronics | 888-236-9828 | Rolling Meadows, IL
Manufacturer of RF and microwave devices including filters, isolators & circulators, directional couplers, power divider/combiners, hybrid, termination and etc. Our R&D team provides outstanding services to quickly bring your product concepts into prototype, and turn the prototype into products.
MCLI | www.800-333-6254 | St. Petersburg, FL
Power dividers, couplers, isolators, circulators, waveguide components, oscillators, filters, hybrids, attenuators, switches, terminations, amplifiers.
Mica Microwave (now Mercury Systems) | 209-825-3977 | Manteca, CA
Circulators, isolators, mixers, equalizers, phase shifters.
Microwave Devices | 888-736-8837 | Franklin, IN
Attenuators, terminators, directional couplers, filters, isolators/circulators, cable assemblies, measurement equipment.
Microwave Resources | 909-627-4125 | Chino, CA
Amplifiers, attenuators, circulators, isolators, frequency multipliers, waveguide couplers, mixers, detectors, filters, pin switches, adapters.
Microwave Technology Corporation (MTC) | +66-35-721-559 to 60 | Wang-noi, Thailand
Microwave passive components of isolators & circulators including coaxial from 80 MHz to 40 GHz. Drop-in or surface mounted from 400 MHz to 20 GHz. Waveguide is up to 40 GHz. Power up to power rating 500 W. Additional product waveguide adaptor & termination.
Murata Electronics | 800-241-6574 | Smyrna, GA
Chip multi-layer (1.0 2.5 GHz), chip dielectric (2450 GHz, Bluetooth), surface mount capacitors, thermistors/resistors, coil (inductors)/delay lines, noise suppression products/EMI filters, resonators, piezoelectric sound components, coaxial connectors, antenna/duplexers, isolators/circulators, PLL modules, VCOs, TCXO, RF diode switches, DC-DC converters, sensors.
Nanowave | +82-43-903-4828 | South Korea
SMD, drop-in, coaxial, waveguide isolators, circulators, directional, hybrid couplers, 2way, 3way, 4way dividers, attenuators, terminations.
Nova Microwave | 408-778-2746 | Clearwater, FL
RF ferrite circulators and isolators that connect, protect and control critical commercial and military wireless telecomm systems. Standard and custom design quality circulators and isolators from 380 MHz to 26.5 GHz.
Pasternack Enterprises | 866-727-8376 | Irvine, CA
Amplifiers to 2 GHz, attenuators 1 - 1000 W DC - 40 GHz, circulators/isolators 1 - 26.5 GHZ w/SMA connectors, combiners/dividers 2 - 12 way 1 MHz - 18 GHz, couplers low & high power 0.5 - 18 GHz, switches manual & diode DC - 18 GHz, terminations 1/2 - 100 W DC-40 GHz, waveguide 1.70 - 40 GHz.
QuinStar Technology | 310-320-1111 | Torrance, CA
Designs and manufactures millimeter-wave products for communication, scientific, and test applications including millimeter-wave products, microelectronic assembly, rapid prototyping, and mass customization. Amplifiers, receivers, oscillators, switches, attenuators, circulators & isolators, filters, waveguide, antennas, and phase shifters, and transceiver & radar subsystems.
Raditek | 408-266-7404 | San Jose, CA
Isolators, circulators, oscillators, synthesizers, couplers, splitters, combiners, hybrids, adaptors, cable assemblies, connectors, terminations, attenuators, bias tee's, lightning protectors.
Renaissance Electronics | 978-772-7774 | Harvard, MA
Manufacturer of RF & microwave sub-systems and components including isolators & circulators, dividers & combiners, waveguide components, coaxial RF switches, switch matrices, base station equipment.
RF & Noise Components Ltd | +44 (0) 5601 06 69 30 | Southend-on-Sea, Essex, UK
Design & manufacturer of RF & microwave components including circulators, isolators, combiners, couplers, dividers and power monitors. Specialising in custom designs to meet individual customer requirements. ISO9001:2008 Approved.
RF-Lambda | 613-592-6858 | Canada
Couplers, circulators, isolators, mixers, attenuators, coupler, power amplifiers, LNA, VCO, switches, oscillators, connectors, adapters.
RTx Technology Co., Ltd | +82-31-743-6275 | South Korea
Filters, duplexers, multiplexers (ceramic/cavity), VCOs & PLL synthesizers, isolators & circulators, up/down converters, combiners & dividers, directional couplers, SAW devices, attenuators, terminators.
Trak Microwave | 888-283-8444 | Tampa, FL
Attenuators, circulators, isolators, comb generators, control devices, couplers, delay line filters, GPS time & frequency, hybrids, IQ mod & demod, mixers, multipliers, oscillators, phase shifters, splitters & combiners, synthesizers, transformers.
Vector Telecom | +61 3 9607 8357 | Melbourne , Australia
Waveguide components and assemblies, coaxial components and antennas.
vidaRF | www.877-777-8432 | Huntersville, NC
Offering High performance isolators, circulators, power dividers, couplers, RF connectors, adapters, custom cable assemblies, attenuators, and terminations. Custom designs available. In-stock items shipped within 24 hours.
VivaTech | +1 818 547 5036 (USA) | +44 750 923 3838 (Intl Mobile)
System front-ends, mm-wave test equipment, source modules, amplifiers, active multipliers, mixers, frequency converters, frequency extension modules, radiometer front-ends, waveguide isolators, waveguide attenuators, passive and active waveguide components and primary noise standards.
Wisewave Technologies (now Ducommun Technologies) | 310-513-7200 | Carson, CA
Amplifiers, antennas, attenuators, PIN diode switches, phase shifters, isolators/circulators, frequency converters, oscillators, couplers, magic tees, coax power dividers, bandpass, low pass, high pass filters, waveguide diplexers, transitions, waveguide to coax adapters, waveguide components, integrated assemblies.