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.
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AFT Microwave | aft-microwave.com
| +49 7191 9659 0 | Germany
Microwave components including circulators, isolators, waveguide and coaxial components,
phase shifters, ferrites, thin film technology.
Advanced Technical Materials, Inc (ATM) | atmmicrowave.com | 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 | aerotek.co.th | 662-332-5035, 311-4448 | Thailand
Coaxial, drop-in, lump,
drop-in lump, flange mount circulators & isolators, 88 MHz - 18 GHz.
Cernex | cernex.com | 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 | channelmicrowave.com | 805-482-7280 | Camarillo, CA
Coaxial and waveguide
isolators, circulators, ISO-adapters, integrated assemblies, filters, terminations.
Charter Engineering | ceiswitches.com | 727-549-8999 | Largo, FL
attenuators, isolators, terminations, circulators, power dividers, couplers.
Corry Micronics | cormic.com | 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 | ditom.com | 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 | dorado-intl.com | 206-574-0900 | Seattle, WA
Planar, horn, 8.2 GHz
to 110 GHz antennas, waveguide isolators & circulators, switches, adapters, connectors.
EM Design, LLC | em-design.com | 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 | emr.com | 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 | ferriteinc.com | 603-881-5234 | Hudson, NH
Circulators, isolators, transmitters.
Filtel | filtel.com | 450-455-6082 | Canada
Couplers, power dividers, isolators, coaxial &
Innertron | innertron.com | +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) | ifi.com | 631-467-8400 | Ronkonkoma, NY
such as tetrode tubes, TWTs, klystrons, and solid state devices. Standard horn antennas and TEM cells.
MCLI | mcli.com | 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)
rf.mrcy.com | 209-825-3977 | Manteca, CA
isolators, mixers, equalizers, phase shifters.
Microwave Devices | mwdevices.com | 888-736-8837 | Franklin, IN
directional couplers, filters, isolators/circulators, cable assemblies, measurement equipment.
Microwave Resources, Inc | microwaveresourcesinc.com | 909-627-4125 | Chino, CA
attenuators, circulators, isolators, frequency multipliers, waveguide couplers, mixers, detectors, filters, pin
Microwave Technology Corporation (MTC) | microwave.co.th | +66-35-721-559 to 60 | Wang-noi,
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 | murata.com | 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 | nanowave.co.kr | +82-43-903-4828 | South Korea
SMD, drop-in, coaxial, waveguide
isolators, circulators, directional, hybrid couplers, 2way, 3way, 4way dividers, attenuators, terminations.
Pasternack Enterprises, Inc | pasternack.com | 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.
Raditek | raditek.com | 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 | rec-usa.com/home.htm | 978-772-7774 | Harvard, MA
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 | rfandnoisecomponents.co.uk | +44 (0) 5601 06 69 30 | Southend-on-Sea,
Design & manufacturer of RF & microwave components, including circulators, isolators, combiners,
couplers, dividers and power monitors. Specialising in custom designs to meet individual customer requirements.
RF-Lambda | rflambda.com | 613-592-6858 | Canada
Couplers, circulators, isolators, mixers,
attenuators, coupler, power amplifiers, LNA, VCO, switches, oscillators, connectors, adapters.
RTx Technology Co., Ltd | rtxtech.com | +82-31-743-6275 | South Korea
multiplexers (ceramic/cavity), VCOs & PLL synthesizers, isolators & circulators, up/down converters, combiners &
dividers, directional couplers, SAW devices, attenuators, terminators.
Trak Microwave | trak.com | 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 Pty Ltd | vectortele.com | +61 3 9607 8357 | Melbourne , Australia
components and assemblies, coaxial components and antennas.
VivaTech | vivatech.biz | +1 818 547 5036 (USA)
+44 750 923 3838 (Intl Mobile)
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)
ducommun.com | 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.