* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Slide 1
Stray voltage wikipedia , lookup
Three-phase electric power wikipedia , lookup
Utility frequency wikipedia , lookup
Electrification wikipedia , lookup
Electric power system wikipedia , lookup
Wireless power transfer wikipedia , lookup
Scattering parameters wikipedia , lookup
Power over Ethernet wikipedia , lookup
Negative feedback wikipedia , lookup
Power inverter wikipedia , lookup
Pulse-width modulation wikipedia , lookup
History of electric power transmission wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Buck converter wikipedia , lookup
Variable-frequency drive wikipedia , lookup
Power engineering wikipedia , lookup
Distribution management system wikipedia , lookup
Instrument amplifier wikipedia , lookup
Public address system wikipedia , lookup
Voltage optimisation wikipedia , lookup
Wien bridge oscillator wikipedia , lookup
Power electronics wikipedia , lookup
Alternating current wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Mains electricity wikipedia , lookup
Opto-isolator wikipedia , lookup
Rectiverter wikipedia , lookup
EMC Test Equipment Amplifiers and Antennas George Barth Product Engineer, Systems ar rf/microwave instrumentation 160 School House Road Souderton, PA 18964-9990 [email protected] Topics • Ideal Amplifier Environment • The EMC Reality • Review of Amplifier Technologies •Tube (Vacuum tube) •Traveling Wave Tube (TWT) Amplifiers •Solid-State: Different classes • Amplifier Use •Proper drive levels •Loads G. Barth Topics •Amplifier Care and Maintenance •Power and Field Measurements •Antennas •Technologies •Applications •Equipment Pairing and Sizing •Power vs. Field G. Barth Ideal Conditions What Amplifiers Love • Always run in a low ambient room temperature • ~72°F • Use in a dust free environment • Have clean power supplied • Install in a fixed location by professionals • Never exceed required input level • depends on specification of each amplifier • Never have a load fail • Connect amplifier only to a matched load • 50 Ω loads <1.5:1VSWR • Only use fully tested and verified coax & waveguide G. Barth Ideal Conditions Majority of the worlds amplifiers are designed for single uses. transmitters, cell phones, radios… These types of applications have known environmental conditions. Load is constant Frequency is usually narrowband Trained professionals are installing Environmental temperature constraints are known Amplifiers can be designed much more easily in these cases and are simple. G. Barth Less Than Ideal Conditions EMC testing does not fall anywhere near ideal or simple conditions. The extremes for the EMC market High VSWR Amplifier is still required to deliver power or at a minimum not be damaged Bad loads, cables, connections Use in many tests, locations, and setups EMC Test engineers & technicians do not have to be amplifier experts G. Barth Less Than Ideal Conditions What is needed Different engineering techniques are used to extend these constraints so the amplifier is more useful. • Better heat removal for extended operating temperature range, which inherently extends the life of the amp • Use better, more durable power supplies • Rugged physical design • Class A design • Added VSWR protection (active protection) • Added ability to handle VSWR G. Barth Amplifier Technologies • Tube (Tetrode tube) • TWT (Traveling Wave Tube) Amplifier • Solid-state •Class A •Class AB •Class B What are the differences? G. Barth Amplifier Technologies FET DC IV-Curve Operating Modes & Bias DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies FET DC IV-Curve Operating Modes & Bias DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V Class A p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V 2 p7 p11: Vstep = 2 V Class AB p4 p3 p2 p1 Class B 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class A DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class A DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class A DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class A DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class A DCIV 8 5V 6.287 A Full current and voltage swing No harmonics p2: Vstep = -2.5 V p1: Vstep = -3 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class B DCIV 8 5V 6.287 A p1: Vstep = -3 V Clipping High Harmonic content p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class AB DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class AB DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 Good V p10 p11 p9 smallp8signal response p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class AB DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class AB DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V Clipping p3: Vstep = -2 V 6 p4: Vstep = -1.5 V and Harmonics introduced p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class AB Shorted Harmonics DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class AB Shorted Harmonics DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class AB Shorted Harmonics DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep =Good -1.5 V p10 p11 p9 small signal performance p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class AB Shorted Harmonics DCIV 8 5V 6.287 A p1: Vstep = -3 V p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 Selfp9biasing p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Class AB Shorted Harmonics DCIV 8 5V 6.287 A Good p1: Vstep = -3 V performance due to self biasing limited to sub octave bandwidth p2: Vstep = -2.5 V p3: Vstep = -2 V 6 p4: Vstep = -1.5 V p10 p11 p9 p8 p5: Vstep = -1 V p6: Vstep = -0.5 V p7: Vstep = 0 V 4 p8: Vstep = 0.5 V p7 p6 p5 p9: Vstep = 1 V p10: Vstep = 1.5 V p11: Vstep = 2 V 2 p4 p3 p2 p1 0 0 40 80 Voltage (V) G. Barth 120 Amplifier Technologies Amplifier Linearity 1dB point Harmonics at 1dB Harmonics above 1dB* Noise power density/ Spurious Ability to handle VSWR* Frequency coverage Tube Bad Good Worst Bad Best Low freq. <250 MHz TWTA Worst Worst Worst Worst Worst High freq. >1 GHz Solid state Class A Best Best Best Good Best Full coverage Solid state Class AB Bad Good Good Good Good to bad Full coverage Solid state Class B Bad Good Bad Best Good to bad Full coverage * Results greatly depends on how the technology is implemented G. Barth Amplifier Technologies Important specifications (other than the power, frequency, and VSWR protection you require) are linearity and harmonics, which are related. High harmonics may have undesirable effects on recorded test levels. As the amplifier approaches compression the harmonics increase. Class A solid state amplifiers seem to have the best performance even into compression. But large variations can be seen depending on the technology used. A recommended level is -6dBc of the field. Example: IEC 61000-4-3 G. Barth Compression •Running the test while the amplifier is in compression will distort the test signal CW signal CW in compression Harmonics • The compressed wave starts to resemble a square wave, producing higher harmonics. G. Barth Compression 47 45.8 dBm 46 45 dBm 45 DB Gain AR 1dB comprestion AR 3dB Compression 44 43 42 dBmOutput Example of compressed power dB Gain for 25S1G4A @ 1500MHz 41 40 7 dB 39 10 dB 38 37 9 dB 36 10 dB 35 34 33 32 -25 -20 -15 -10 -5 dBm Input Compression points at one frequency G. Barth 0 Amplifier Driving What is the correct drive level to the amplifier? There will always be a max drive level before damage. • Most of AR’s amps have +13dBm max input level. • In most cases there is no reason to come even close to max input level. • Amplifiers are rated with a 0dBm input to reach rated output. • Most testing should not be done with saturated power •Therefore -5 - -10 dBm may be all you need to drive the amplifier G. Barth Amplifier Driving This brings us to the proper input to produce the desired linear output G. Barth Amplifier Driving An amplifier requiring 0 dBm input to reach rated output does not mean 0dBm of input is required to get the results you may need. TWT amplifiers in some cases with a 0dBm input and full gain will be over driving the TWT. Over time this could be damaging. Application Note # 45 Input Power Requirements… For further explanation G. Barth Amplifier & VSWR • The amplifier’s ability to deal with VSWR will determine the possible use and application. • TWTAs have a relatively low threshold to VSWR • The TWT will fail at high VSWR without protection or precautions. • 2:1 VSWR at rated power 1. Fold back at 20% reflected power (best) [AR] pulsed amps fold back at 50% reflected power [AR] 2. Shutdown at 2:1 VSWR 3. Rely on user to take responsibility to be proactive • Low Power Solid State can have high threshold to VSWR • Dependent on technology used • Infinite VSWR handling, no protection needed [AR] G. Barth Amplifier & VSWR • High Power Solid State can have high threshold to VSWR • Dependent on technology used • High VSWR handling, some protection required • Can handle up to 50% of rated power (6:1 VSWR) when used at full power • Folds back so that reverse power does not exceed reverse power limit • Why can’t higher power amplifiers handle infinite VSWR like lower power versions? • Combining • Components see up to twice the power (4x voltage and current) • Combiners also act as splitters and direct energy back to output stages G. Barth Large Amplifier Makeup OUT IN Attenuator Pre-amplification splitters G. Barth Final stages combiners Amplifier Technologies • Why is protection from mismatch needed? • There is only so much that can be done to protect the amplifier without adding exorbitant cost G. Barth Care • General care • Keep original packaging for shipping • If new packaging is required contact AR for suggestions • Do not disconnect RF connection while amplifier is not in standby! • The amplifier is protected from this but you are not! • Make sure heat is not re-circulated back into amplifier • Temperature is monitored and protected in the amplifier, but cooler is always better G. Barth Care • Tube [Vacuum tube] amplifiers • Oil cooling system • New unit: make sure to fill oil correctly. • Do not tip over and place on it’s side to work on! • Will drive full power and not fold-back into any load. • Maintain recommended operating temperature. • Over time tubes will slowly decrease power output and require replacement. G. Barth Care • TWTA • TWT is most expensive part of the amplifier (Protect It) • Make sure heat outtake and intake are not confined • Be very careful not to overdrive input! • This can be damaging to the TWT. • Take care not to let the amplifier sit unused for extended periods of time [months – years]. • The TWT will “Gas up”, then when activated the Tube may be damaged. • A De-gassing start up routine needs to be used • Do not leave the TWTA powered up and not being used for extended periods of time. • Tube can “Gas up” • Do not disable sleep mode feature • Take care not to use badly mismatched loads • AR’s amps are fully protected for all mismatches but is still stressful to TWT G. Barth Care •Solid-state •Do what ever you want they can take it! G. Barth Power and Field Measurement What is the proper way to measure power and field? • What is the measurement device • Power meter (w/directional coupler) • Diode sensor • Thermocouple sensor • Peak power meter • Field probe • Diode sensor • Thermocouple sensor • Pulse probe • Spectrum analyzer G. Barth Power and Field Measurement Technology differences Diode Thermocouple • More sensitive • Can measure true RMS of a CW signal. • Can be used to measure RMS of modulated signals if used within the linear region. Usually this is in the lower region but it’s difficult to know exactly. • A signal in compression can have error in the actual reading. •Faster response • Less sensitive • Less dynamic range • Measures true RMS of any signal G. Barth Power and Field Measurement Technology differences Broad-Band Device (power meter, field probe) • Will measure whole frequency spectrum including harmonics • Care must be taken that harmonics are not contributing to reading • Can be very accurate if used correctly • Easy setup and use G. Barth Frequency Selective Device (Spectrum Analyzer) • Can discern between different frequency signals • Measures peak – RMS = Peak/SQRT(2) • Can measure modulated signals • Possible time consuming setup Power and Field Measurement • For measuring amplifier output, using a directional coupler with a power meter is acceptable. Care should be taken in a reverberation chamber, for example. • In most ALSE testing, forward power is a relative number and care only needs to be taken that this can be reproduced. • If harmonics are a concern harmonic filters can be used. G. Barth Power and Field Measurement Verify measurements are correct when using a broad-band device to take measurements • It is a good idea to verify the readings are correct with a spectrum analyzer. 1. Run a calibration with the power meter and then a calibration with the spectrum analyzer to see if the forward power reading matches up 2. Use an antenna and spectrum analyzer to spot check V/m reading from probe during calibration especially where the amplifier is being driven hard. Don’t assume that if the harmonics are out of band that they are no longer a factor! (amplifier, probe, antenna…) G. Barth Antennas E-Field Generator • 10kHz-100MHz • Field created between elements or elements and ground •Non-radiating • Power limited by Impedance Transformer G. Barth Antennas Biconical (Bicon) • 20MHz-300MHz • Extremely broad beam width • Power limited by Impedance Transformer (Balun) G. Barth Antennas Log Periodic (LP) • 26MHz-6GHz • Beam width narrows with frequency • Power limited by input connector and antenna feed G. Barth Antennas Horn • 200MHz-40GHz • High Gain • Beam width dependant on design • Power limited by input connector or waveguide G. Barth Equipment Pairing and Sizing Pairing Considerations •Frequency •Antennas and Amplifiers do they match? •Will switching be required? • Power • Can antenna handle amplifier power available? • RF connectors compatible? •Cabling? G. Barth Equipment Pairing and Sizing Pairing Considerations Illumination of EUT • 3dB beam width (test distance) • Will windowing be required? 1.5 m 1m 74° W 2 tan 1 2 D 2m 41° W 2D tan 2 D G. Barth W 2 tan 2 3m 28° Equipment Pairing and Sizing Sizing Considerations •Field Strength • Test distance? • Modulation? (AM, AM constant peak, Pulse) •Losses •Cables •Chamber effects •Reflections (EUT) •VSWR (antenna) •Margin G. Barth Equipment Pairing and Sizing Calculating Power Required to Get Field •Frequency dependant GAIN 16 14 V meters2 Watts m 30 10 GaindBi 10 G A IN ( d B i) 12 10 8 6 4 2 0 700 1000 1750 3000 4500 6000 7500 9000 10500 12000 13500 15000 16500 18000 FREQUENCY (MHz) G. Barth Equipment Pairing and Sizing Calculating Power Required to Get Field •Frequency dependant AT4418 Field Strength @ 1 Meter 1000.00 WattsNew V m New 2 WattsOld V m Old 2 300W 200W V/m 100W 100.00 50W 20W 2 MetersNew WattsNew WattsOld MetersOld 2 10W 10.00 700 1500 3500 6000 8500 Frequency (MHz) G. Barth 11000 13500 16000 Equipment Pairing and Sizing Calculating Power Required to Get Field •Power calculated from graphs or formulas is P1dB •Add for system losses •Cables •Chamber effects •Reflections (EUT) •VSWR (antenna) •Add Margin G. Barth Any questions? Thank you for your attention!!! George Barth Product Engineer, Systems ar rf/microwave instrumentation 160 School House Road Souderton, PA 18964-9990 [email protected] G. Barth