INTRODUCTIONCIRCULATORSISOLATORSTERMS AND DEFINITIONSCAUTIONARY NOTESQUALITY GUARANTEESTANDARD TEST SPECIFICATIONSAPPLICATIONSDATA SHEETSupersedes data of July 1994File under Professional Components, PC061998 Feb 20PROFESSIONAL COMPONENTSGENERALCirculators and isolators1998 Feb 20 2Philips SemiconductorsCirculators and isolators GENERALINTRODUCTIONThis Data Handbook gives only a selection of circulatorsand isolators from our production line which, we think, areof common interest and which shows our capability.Should you require other executions, different connectors,different frequencies or any other data, please contact us.Circulators and isolators are key elements in modern VHF,UHF, and microwave engineering. Their fundamentalproperty of non-reciprocity is capable of simplifying theconstruction and improving the stability, efficiency andaccuracy of radar, communication and testing systems,and industrial heating applications.The devices contain a core of ferrite material biased by astatic magnetic field. This field orients the electron spinswithin the ferrite to produce a gyromagnetic effect. Thenon-reciprocal behaviour occurs when a RF signal,applied perpendicular to the biasing field, interacts with theprecessing electrons to set up a standing-wave patternwithin the core.CIRCULATORSA circulator is a passive non-reciprocal device with three ormore ports. Energy introduced into one port is transferredto an adjacent port, the other ports being isolated.Although circulators can be made with any number ofports, the most commonly used are 3-port and 4-port ones,the symbols for which are given in Figs 1 and 2.Energy entering into port 1 emerges from port 2; energyentering into port 2 emerges from port 3, and so on incyclic order.Fig.1 Symbol for 3-port circulator.handbook, halfpage213MBK615Fig.2 Symbol for 4-port circulator.handbook, halfpage2413MBK616ISOLATORSAn isolator is a passive non-reciprocal 2-port device whichpermits RF energy to pass through it in one direction whilstabsorbing energy in the reverse direction.Fig.3 Symbol for an isolator.handbook, halfpageMBK6171998 Feb 20 3Philips SemiconductorsCirculators and isolators GENERALTERMS AND DEFINITIONSFrequency rangeThis is the range within which the circulator or isolatormeets the guaranteed specification.IsolationIn a circulator, isolation is the ratio, expressed in dB, of thepower entering a port to the power scattered into theadjacent port on the side opposed to the normal circulation(matched source and the other ports correctly terminated).In an isolator, isolation is the ratio, expressed in dB, of theinput power to the output power for signal injection in thereverse direction (matched source and load).Insertion lossThe attenuation that results from including the device inthe transmission system. It is given as a power ratio,expressed in dB, which compares the situation before andafter the insertion of a circulator/isolator (matched sourceand the other ports correctly terminated).Maximum powerIn a circulator, the maximum power is the largest power itcan handle at sea level and at maximum ambienttemperature when one port is terminated with a mismatchgiving a VSWR of 2, whilst the next port is matched with aVSWR of 1.2 or less, unless otherwise stated. This powervalue must not be exceeded. If the mismatch of the load isexpected to exceed a VSWR of 2, a circulator of higherpower handling capacity should be used.The maximum power is the maximum continuous-wavepower unless a maximum peak power is separately stated.If this value is exceeded the circulator can be damaged byarcing in its internal transmission structure. Power valuesare valid for one signal passage only. If more than onesignal passes through the circulator, the peak power of thecombined signal should not exceed the indicatedmaximum peak power.In an isolator, the maximum power is the largest power thatmay be passed through it in the forward direction into aload with a VSWR of 2, unless otherwise stated. Thispower value must not be exceeded.Temperature rangeThe ambient temperature range within which circulatorsand isolators function to specification. (When necessary,special temperature compensation is built in forcirculators.) Circulators still function outside thetemperature range but their electrical behaviour may thenbe far outside the guaranteed specifications. However, nopermanent damage can be expected unless a largetemperature rise is caused by excessive power handling.CAUTIONARY NOTESCirculators and isolators have internal fields that arecarefully adjusted for optimum operation; they should not,therefore, be subjected to strong external magnetic fields.During storage and transport a minimum distance of 10mm to other circulators/isolators and ferromagneticmaterial is recommended. During operation this distanceshould be at least 20 mm.Care must be taken that condensation of humidity,especially in water-cooled items, does not occur.QUALITY GUARANTEESubject to the Conditions of Guarantee the Manufacturerguarantees that circulators and isolators supplied to thepurchaser meet the specifications published in theManufacturer’s Data Handbook and are free from defectsin material and workmanship.STANDARD TEST SPECIFICATIONSInitial measurementsThese measurements have been carried out at roomtemperature and at the extreme temperatures, with apower level not exceeding 10 mW.Tropical testThis test has been carried out completely in accordancewith IEC 68 test D, accelerated damp heat. This testbegins with the temperature at 55 ± 2 °C and R.H. at 95 to100% for a period of 16 hours, followed by a period of8 hours with the temperature at + 25 °C and R.H. 80 to100% to complete the 24-hour cycle: the test consists of6 uninterrupted cycles.Vibration testThis test has been carried out completely in accordancewith MIL-STD-202D, method 201A: frequency range 10 to55 to 10 Hz for 2 hours in each of the X, Y and Z directions,with a total excursion of 1,5 mm.1998 Feb 20 4Philips SemiconductorsCirculators and isolators GENERALThermal shock testThis test has been carried out completely in accordancewith MIL-STD-202D, method 107C under condition A: 5cycles with extreme temperatures of −55 °C and + 85 °C;each cycle of 1 hour’s duration.Mechanical shock testThis test has been carried out in accordance withMIL-STD-202D, method 213A under condition G: peakvalue 100 g, duration 6 ms, and also with extreme peakvalues up to 800 g, duration approximately 1 ms for eachdevice,