Unit iii mirowave passive components
- 1. UNIT III MIROWAVE PASSIVE COMPONENTS CONTENTS: Microwave frequency range, significance of microwave frequency range - applications of microwaves. Scattering matrix -Concept of N port scattering matrix representation- Properties of S matrix- S matrix formulation of two-port junction. Microwave junctions - Tee junctions –Magic Tee - Rat race - Corners - bends and twists - Directional couplers - two hole directional couplers- Ferrites - important microwave properties and applications – Termination - Gyrator- Isolator- Circulator - Attenuator - Phase changer – S Matrix for microwave components – Cylindrical cavity resonators.
- 2. MICROWAVE FREQUENCY RANGE Microwaves are a form of electromagnetic radiation with wavelengths ranging from as long as one meter to as short as one millimeter; with frequencies between 300 MHz (100 cm) and 300 GHz (0.1 cm). This broad definition includes both UHF and EHF (millimeter waves), and various sources use different boundaries.
- 3. FREQUENCY BAND DESIGNATION FREQUENCY BAND DESIGNATION TYPICAL SERVICE 330kHz Very low frequency (VLF) Navigation, sonar 30300 kHz Low frequency (LF) Radio beacons, navigational aids 3003,000kHz Medium frequency (MF) AM broadcasting, maritime radio, Coast Guard communication, direction finding 330MHz High frequency (HF) Telephone, telegraph, and facsimile; shortwave international broadcasting; armature radio; citizen's band; ship to coast and Ship to aircraft communication 30300MHz Very high frequency (VHF) Television, FM broadcast, air traffic control, police, taxicab Mobil radio, navigational aids 3003,000MHz Ultrahigh frequency (UHF) Television, satellite communication, radiosonde, surveillance radar, navigational aids 330GHz Super high frequency (SHF) Airborne radar, microwave links, common carrier land mobile communication, satellite communication 30300GHz Extreme high frequency (EHF) Radar, experimental
- 4. MICROWAVE FREQUENCY BAND DESIGNATION FREQUENCY OLD BAND DESIGNATION NEW BAND DESIGNATION 500-1000MHz VHF C 1-2GHz L D 2-3GHz S E 3-4GHz S F 4-6GHz C G 6-8GHz C H 8-10GHz X I 10-12.4GHz X J 12.4-18GHz Ku J 18-20GHz K J 20-26.5GHz K K 26.5-40GHz Ka K
- 5. APPLICATIONS OF MICROWAVES • Antenna gain is proportional to the electrical size of the antenna. At higher frequencies, more antenna gain is therefore possible for a given physical antenna size, which has important consequences for implementing miniaturized microwave systems. • More bandwidth can be realized at higher frequencies. Bandwidth is critically important because available frequency bands in the electromagnetic spectrum are being rapidly depleted. • Microwave signals travel by line of sight are not bent by the ionosphere as are lower frequency signals and thus satellite and terrestrial communication links with very high capacities are possible. • Effective reflection area (radar cross section) of a radar target is proportional to the target’s electrical size. Thus generally microwave frequencies are preferred for radar systems.
- 6. APPLICATIONS OF MICROWAVES • Various molecular, atomic, and nuclear resonances occur at microwave frequencies, creating a variety of unique applications in the areas of basic science, remote sensing, medical diagnostics and treatment, and heating methods. • Today, the majority of applications of microwaves are related to radar and communication systems. Radar systems are used for detecting and locating targets and for air traffic control systems, missile tracking radars, automobile collision avoidance systems, weather prediction, motion detectors, and a wide variety of remote sensing systems. • Microwave communication systems handle a large fraction of the world’s international and other long haul telephone, data and television transmissions. • Most of the currently developing wireless telecommunications systems, such as direct broadcast satellite (DBS) television, personal communication systems (PCSs), wireless local area networks (WLANS), cellular video (CV) systems, and global positioning satellite (GPS) systems rely heavily on microwave technology. • MICROWAVE RADAR SYSTEMS(Duplexer. pulsed radar, Doppler effect) • MICROWAVE COMMUNICATION SYSTEMS(Terrestrial systems, LOS, heterodyne repeater, Satellite communication systems) • INDUSTRIAL APPLICATION OF MICROWAVES(Microwave Heating-oven, Medical applications-Diathermy, Hyperthermia, Thickness measurement, Moisture measurement in solid material)
- 7. SCATTERING MATRIX • A set of linear equations can be written to describe the network in terms of injected and transmitted power waves 2221212 2121111 aSaSb aSaSb 2 1 2221 1211 2 1 a a SS SS b b jportatinjectedPower iportatmeasuredPower a b S j i ij Sii = the ratio of the reflected power to the injected power at port i Sij = the ratio of the power measured at port j to the power injected at port i
- 8. Concept of N port scattering matrix representation N 3 2 1 NN2N1N ... N23231 N32221 N11211 bN b b a ... a a a s.....ss .......... s.....ss s.....ss s.....ss . . 2 1
- 10. MICROWAVE PASSIVE COMPONENTS 1.REFLEX CLYSTRON
- 11. 2.ISOLATOR 3.MAGIC TEE 4.E-PLANE TEE 5.H-PLANE TEE 6.CIRCULATOR 7.FREQUENCY METER
- 13. 13.PHASE SHIFTER 14.TWIST 15.TUNER 16.MULTI HOLE DIRECTIONAL COUPULER
- 14. MICROWAVE ANTENNAS 1.SPIRAL ANTENNA 2.PARABOLIC ANTENNA 3.MIROSTIPE ANTENNA(PATCH ANTENNA) 4.HORN ANTENNAS
- 15. REFLEX KLYSTRON
- 16. Magnetron
- 20. RADIATION PATTERN CYLINDRICAL RESONANT CAVITY
- 21. 0 0 0 3231 2321 1312 SS SS SS S 331313 131112 131211 SSS SSS SSS S S-MATRIX FOR MICROWAVE –T JOINT 0 0 0 3231 2321 1312 SS SS SS S 331313 131112 131211 SSS SSS SSS S S-MATRIX FOR MICROWAVE –H JOINT 2313 SS
- 22. 00 00 00 00 4241 3231 2423 1413 SS SS SS SS S 00 00 00 00 4341 3432 2321 1412 SS SS SS SS S S MATRIX FOR MAGIC T HYBRID RING(RAT RACE CIRCUIT)
- 23. dBPP )/(log10 4110Coupling Factor(dB) dBPP )/(log10 4110Directivity (dB) P1- power input to port1 P3-power output from port 3 P4-power output from port 4 S-matrix of Directional coupler
- 25. REFERENCES: 1. Samuel Y Liao, “Microwave Devices & Circuits” , Prentice Hall of India, 2006 2. Annapurna Das and Sisir K Das, “Microwave Engineering”, Tata McGrawHill Inc., 2004.