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MICROWAVE. Primer. Andrew Wallace MEng (Hons) AMIEE Regional Sales Specialist. 1. An Introduction To Microwave Theory And Components. Electromagnetic Spectrum. 10km 100m 1m 1cm 100 m m 1 m m 100A 1A. 100km 1 km 100m 10cm 1mm 10 m m 0.1 m m 10A .

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## MICROWAVE

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**MICROWAVE**Primer Andrew Wallace MEng (Hons) AMIEE Regional Sales Specialist**Electromagnetic Spectrum**10km 100m 1m 1cm 100mm 1mm 100A 1A 100km 1 km 100m 10cm 1mm 10mm 0.1mm 10A ELF VLF LF MF HF VHF UHF SHF EHF UV X-rays Milli- meter Microwave Infrared 3 x 102 3 x 105 3 x 107 3 x 109 3 x 1011 3 x 1013 3 x 1015 3 x 1017 3 x 104 3 x 106 3 x 108 3 x 1010 3 x 1012 3 x 1014 3 x 1016 3 x 1018**Coaxial Conductors**Outer Conductor Half Wavelength Inner Conductor Er a Electric Field Magnetic Field b Impedance : Z = 138 log10 b ÖEr a**Ground Plane**Stripline Conductors Dielectric material Copper / gold strip Metallic ground strip Ground Plane**Microstrip Conductors**Ground Plane Copper / gold strip Dielectric material Metallic ground strip Ground Plane**lg / 2**b Side View a lg / 2 Cross Section Electric Field Magnetic Field Top View Wave Propagation**Why 50W Connectors**1.4 Attenuation is lowest at 77W 1.2 50W standard Normalized Values 1 0.8 Power handling capacity peaks at 30W 0.6 1 20 30 40 50 60 70 100 Characteristic Impedance (W)**Connector Standards**GPC 14 14 mm 50: DC to 8.5 GHz IEEE 287 & 75: DC to 2 GHz IEC 457 Type N 7 mm 50: DC to 18 GHz Mil-C-39012 & 75: DC to 2 GHz BS 9210 BNC/TNC 7 mm 50: DC to 4 GHz Mil-C-39012 & 75: DC to 2 GHz BS 9210 Precifix AA 7 mm 50: DC to 18 GHz IEEE 287 & IEC 457 GPC 7 7 mm 50: DC to 18 GHz IEEE 287 & IEC 457 SMA 4 mm 50: DC to 26 GHz Mil-C-39012 & BS 9210 GPC 3.5 3.5 mm 50: DC to 34 GHz Type K 2.92 mm 50: DC to 46 GHz**Limiters**Pout Watt Pin Watt**Load**Directional Couplers C Coupled Input Through A B**Coaxial Coupler**Waveguide Coupler Directional Couplers**Balun**Detector 50W 50W 50W Test Port ZX [ ] ZX - 50 ZX + 50 Bridges & Autotesters Source Vdetector = Const = Const G**Diode Detector**DC Block C1 DC Voltage Output Microwave Input C2 50W R**Power Splitter**Output 50W Input 50W Output**Wilkinson & Resistive Power Dividers**Output A Input 100W Loss 3dB Output B 16.66 W Output A Input 16.66W Loss 6dB Output B 16.66W**Circulators & Isolators**A B Low loss A to B B to C C to A High loss A to C C to B B to A C**PIN Devices**W P+ I N+ W = Width Of Layer I**H DC**DC Magnetic Field Electromagnet H AC YIG sphere R.F. Input AC Magnetic Field R.F. Output The YIG Oscillator**Electromagnet**YIG sphere Active Device R.F. Output Fo = g Ho YIG Frequency**]**[ Travelling Wave Tubes (TWT) Focusing Magnet Cathode Collector Microwave Signal Electron Flow Focusing Magnet R.F. O/P Axial Velocity Of Electron Microwave Signal @ Velocity**2. Scalar Analysis : An Introduction To Measurements**And Concepts.**2-Port Scalar Analysis**VINC VTRANS DUT VREF**Scalar Measurement Coefficients**• What quantities can be measured by a Scalar Network Analyzer? • Insertion Loss/Gain • Return Loss, VSWR (Reflection Coefficient) • Relationship between reflection expressions • t = magnitude of transmission coefficient • r = magnitude of reflection coefficient (Biggest = 1 , Smallest = 0) • VSWR = 1 + r Return Loss = -20 log10(r) dB • 1 - r • r = | G | t = | T |**Return Loss - Some Typical Values**Return loss VSWR Short / Open circuit 0dB ±1 Matched load Theory dB 1 0 Practice 40dB 1.02 0.01 Matched antenna (Broadband) 14 - 26dB 1.1 - 1.5 0.05 - 0.2 Typical component 14dB 1.5 0.2 Adapter (Co-ax) >26dB <1.1 <0.05 Waveguide / Co-ax transition 14 - 26dB 1.1 - 1.5 0.05 - 0.2 Waveguide flange 26 - 34dB 1.04 - 1.1 0.02 - 0.05**DUT**Scalar Analyzer Block Diagram Display Detector Ramp Generator Source**Frequency Response**Basic System - Single Detector**Simple Return Loss Measurement**DUT RF OUT Coupled Detector port**Return Loss and Insertion Loss**Basic system - Autotester and Detector**Test Points**Sources Of Error A B C A C B Adapter RF DUT Wanted Reflected Signal Wanted Reference Signal Load Match Adapter Wanted Transmitted Signal Source Match Test Port Match Directivity**DUT**Transmission Errors - Frequency Response Detector Frequency Response Frequency Response Of Cables**Transmission Errors - Source & Load Match**Calibration Detector lo DUT rs rd r1 r2 Transmission Uncertainty (worst case) u = (rs * rd) + (rs * r1 * lo ) + (rd * r2 * lo) + (rs * r1 * r2 * rd * lo) or in dB = 20 log10 (1 + u)**Reflection Errors - Frequency Response**Autotester test port frequency response Autotester**ra = rm + [D+ rs ra2]**ra DUT Reflection Errors - Directivity & Source Match Where: ra = Actual Reflection Coefficient rm = Measured Reflection Coefficient rs = Test Port Match D = Directivity rs D**Waveguide Return Loss - single coupler**Single coupler solution**Waveguide Return loss - dual coupler**Dual couplers measure incident and reflected power

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