Vector network analysis Calibration and advanced measurements

Transcription

1 Vector network analysis Calibration and advanced measurements

2 Application examples (I) Production-line testing On-wafer testing Datum VNA training Titel R&S 2 Canada 2

3 Application examples (II) RCS measurement Pulsed measurements Datum VNA training Titel R&S 3 Canada 3

4 Wave quantities and S-parameters 2 ports Wave quantities: Incident wave: a i Reflected/Transmitted wave: b i S-parameters: Forward meas.: a 2 = 0 S 11 : reflection coef. (b 1 / a 1 ) Reverse meas.: a 1 = 0 S 22 : reflection coef. (b 2 / a 2 ) S 21 : fwd transmission coef. (b 2 / a 1 ) S 12 : rev transmission coef. (b 1 / a 2 ) Datum VNA training Titel R&S 4 Canada 4

5 Why do we measure S-parameters? At DC and low frequencies, voltages and currents are typically measured using capacitive probes This technique doesn t apply to radio frequencies... it creates short or open circuits depending on the frequency S-parameters relate incoming and reflected waves in the defined reference plane. [S] stands for scattering. S-parameters are complex values (amplitude and phase) Ideal for RF measurements because measurements can be performed in a matched and practical state (usually 50 Ω) using wave quantities When components are cascaded, it is easy to compute the overall performance by multiplying the S-parameters matrices Datum VNA training Titel R&S 5 Canada 5

6 Relationship between S-parameters and voltage/current Datum VNA training Titel R&S 6 Canada 6

7 Basic architecture of Vector Network Analyzers How do we separate the waves at the source level from the ones at the receiver level? => using a directional element Receivers and detectors required to measure the level of the wave quantities Heterodyne concept used to process data in intermediate frequency (IF) => LO generator to convert the RF frequency to IF Detector Receivers topology Directional coupler Filter A/D Datum VNA training Titel R&S 7 Canada 7

8 Types of directional elements Depending on the frequency range of a VNA, different kind of directional elements are used: VSWR Bridge Directional Coupler (above 20 GHz) Z L Z O Z L a1 b1 Input Transmission path a3 b3 U a2 b2 Coupling Path Isolation Path a4 b4 Z L Z L Z L Datum VNA training Titel R&S 8 Canada 8

9 Agenda l Calibration of the vector network analyzer l What is the purpose of calibration l Calibration methods l Measurement error l Dynamic range l Measurement Accuracy l Group delay measurement l Amplifier measurement l Linear parameters l Non-linear parameters l Time domain l Modes l Gating and filtering in time domain l Applications Datum VNA training Titel R&S 9 Canada 9

10 Agenda l Calibration of the vector network analyzer l What is the purpose of calibration l Calibration methods l Measurement error l Dynamic range l Measurement Accuracy l Group delay measurement l Amplifier measurement l Linear parameters l Non-linear parameters l Time domain l Modes l Gating and filtering in time domain l Applications Datum VNA training Titel R&S 10 Canada 10

11 Calibration vs. system error correction Calibration: Instrument has to be calibrated once a year by an appropriate service to check its raw performance System error correction (SEC): performed before a measurement to take into account the testing setup Reference impedance environment (e.g. 50 Ω) Test cables(s) / adaptors Transmission line type (coaxial, wave guide, microstrip, etc) Calibration kit Calibration technique Datum VNA training Titel R&S 11 Canada 11

12 Main purpose of SEC l Set the reference plane to properly measure device under test (at the port of VNA by default) => critical for phase / delay l Take into account imperfections of VNA VNA reference plane DUT reference plane Datum VNA training Titel R&S 12 Canada 12

13 Setup: importance of test cables l Connector type should be selected depending on frequency range l Cables are the weak link in your setup l Connector type of the test cable should match with the one of the used cal. kit l Phase stable cables are required for accurate measurements Datum VNA training Titel R&S 13 Canada 13

14 System error correction (I) Error sources occuring during VNA measurement measurement errors stochastic errors systematic errors l No possible correction l Stability of instrument (thermal drift) l Stability of test setup (connection repeatability, cable position) l Noise (sources and receivers) l Error sources corrected by system error correction : l Source mismatch l Port mismatch l Coupler directivity l Frequency response Datum VNA training Titel R&S 14 Canada 14

15 System error correction (II) Good practices to reduce stochastic errors: Allow warm up time of the instrument (reduce thermal drift) Use suitable connectors and cables (torque properly), clean connectors, and try to minimize the movement of the test cables (repeatability) Use IF bandwidth as small as possible (minimize noise) => sweep time!!! Datum VNA training Titel R&S 15 Canada 15

16 System error correction (III) Effect of the IF filter bandwidth on dynamic range: Example of trace noise with IFBW = 1 MHz 0.1 db If IFBW is increased by factor 10: l Dynamic range drops by 10 db l Measurement speed is 10 times faster Datum VNA training Titel R&S 16 Canada 16

17 System error correction (IV) Amplitude and phase variations when a cable is bent: Example of typical variation as a function of temperature 10 MHz 1 GHz 3 GHz 4,5 GHz 6 GHz 8,5 GHz Mag db/ C Phase / C 0,003-0,026 0,003 0,014 0,003 0,05 0,012 0,088 0,012 0,068 0,014 0,23 Datum VNA training Titel R&S 17 Canada 17

18 System error correction (V) Reflection coefficient measurement: The instrument measures S 11M, but the actual quantity is S 11A Incident (a 1 ) S 11M S 11A Reflected (b 1 ) Datum VNA training Titel R&S 18 Canada 18

19 System error correction (VI) 1-port error model: 3 terms To measure the actual a1 and b1, imperfections are modelized in the error terms formed by E DF, E SF and E RF Port 1 a 1 1 S 11M E DF E SF S 11A b 1 E RF E DF = Directivity E SF = Source match E RF = Frequency response (reflection) Datum VNA training Titel R&S 19 Canada 19

20 System error correction (VII) Relationship between S 11A, S 11M, and the error terms: Port 1 a 1 1 S 11M E DF E SF S 11A b 1 E RF S M = S 11 11M = b a 1 E 1 DF S + 1 S 11A E E 11A RF SF Datum VNA training Titel R&S 20 Canada 20

21 System error correction (VIII) 2-port error model (One path two port): 5 terms Compared to the 1-port model, the error terms E TF and E XF are added E XF Port 1 Port 2 a 1 1 S 21A E TF b 2 S 11M E DF E SF S 11A S 21M b 1 E RF E DF = Directivity E SF = Source match E RF = Reflection traking E TF = Transmission tracking E XF = Isolation Datum VNA training Titel R&S 21 Canada 21

22 System error correction (IX) Full 2-port error model: forward measurement (6 terms) Measurement done in two steps (forward a 2 = 0 and reverse a 1 = 0) Even if only S 11 is displayed, the forward and reverse meas. are performed E XF a 1 1 b 2 E DF E SF S11 S 21 S 22 E LF E TF S 12 b 1 E RF E DF = Directivity E SF = Source match E RF = Reflection traking E TF = Transmission tracking E LF = Load match E XF = Isolation Datum VNA training Titel R&S 22 Canada 22

23 System error correction (X) Coaxial calibration standards: Open: C = C0 + C1 f + C2 f 2 + C3 f 3 Parameters: Electrical length Capacitance Loss Short: Parameters : Electrical length Inductance Loss 50 Ω Match: Charge (50 Ω) Datum VNA training Titel R&S 23 Canada 23

24 System error correction (XI) Datum VNA training Titel R&S 24 Canada 24

25 System error correction (XII) Two major classes of error correction techniques: Scalar calibration (Normalization or Response calibration): Compensates frequency response only Does not require measurement of phase during calibration Measure one standard only Response = Data / MEM Standard Vector calibration: Requires measurement of phase during calibration Compensates all major sources of systematic errors Requires at least 3 calibration standards Various techniques available based on the application contraints Datum VNA training Titel R&S 25 Canada 25

26 System error correction (XIII) Different types of system error correction are available for VNAs: l Standard calibration (use of well defined calibration standards such as open, short or match). Possibility to calibrate 1 port only. l OSM (O=Open, S=Short, M=Match) l TOSM (T=Thru) l Self calibration / partial (use of lines or network elements). Calibration only on 2 ports or more). l Normalization and 1 path-2 ports l LRL, TRL, LRM (L=Line, R=Reflect) l TRM, TSM, TOM, TNA (N=Symmetrical Network, A=Attenuator) l Automatic calibration: UOSM (U=Unknown thru) Datum VNA training Titel R&S 26 Canada 26

27 System error correction (XIV) Comparison of calibration methods: Datum VNA training Titel R&S 27 Canada 27

28 System error correction (XV) Mechanical calibration kits: Calibration modules (uses a series of electronic switches): Datum VNA training Titel R&S 28 Canada 28

29 System error correction (XVI) Effective system data for different kind of calibration kits Example between 10 MHz and 15 GHz (units in db): Parameter Economical (mech.) Auto. module (El.) High-quality (mech.) Directivity 23 to to to 40 Source match 20 to to to 36 Reflection tracking to to to 0.2 Load match 21 to to to 40 Transmission tracking 0.10 to to to 0.2 Datum VNA training Titel R&S 29 Canada 29

30 Measurement accuracy (I) Because the directional coupler is not ideal, a leaky signal is transmitted directly to the reference receiver even if there is no reflection on the test port. Directivity is a factor used to quantify the amplitude of the residual signal. Es: incident signal Directional coupler Test port Z0 Ideal match No reflection Ed: residual signal (Directivity) Datum VNA training Titel R&S 30 Canada 30

31 Measurement accuracy (II) After calibration, the directivity of the measurement system can be evaluated An air line is inserted between the test port and a match to create ripples in the frequency range of interest Ed Ex Measure of ripples The measured ripple is used to evaluate the directivity Es: incident signal Directional coupler Test port Zx Offset of the match Ed: residual signal (Directivity) Ex: measured signal Datum VNA training Titel R&S 31 Canada 31

32 Measurement accuracy (III) Accuracy: convertion table XdB Ref+X + Ref-X Ref+/-X l X db below Ref l Uncertainty of +xdb/-xdb around the measured value (Ref+X) X (Ref-X) (Ref) Datum VNA training Titel R&S 32 Canada 32

33 Measurement accuracy (IV) 1.4 db ripple at 1.65 GHz 1.4 db around a RL of db Directivity = db = 42.5 db Datum VNA training Titel R&S 33 Canada 33

34 Measurement accuracy (V) l Example : VSWR of Zx = 1.29 => RL = 18 db db l Directivity Ed = 40 db Ed db Uncertainty 1.38 db l The convertion table provides the error caused by directivity on a VSWR of 1.29 Ex Es: incident signal Directional coupler Test port Zx Non ideal match Partial reflection Ed: residual signal (Directivity) Ex: measured signal Datum VNA training Titel R&S 34 Canada 34

35 Measurement accuracy (VI) Similarly, the source match (or port match) can be measured In this case, an air line is inserted between the test port and a short Ed Ex Measure of ripples Directional coupler Test port Es: incident signal Zx Short circuit Ex: measured signal Ea: reflected signal Datum VNA training Titel R&S 35 Canada 35

36 Measurement accuracy (VII) Values given by the manufacturer for accuracy in reflection Datum VNA training Titel R&S 36 Canada 36

37 Measurement accuracy (VIII) Measurement accuracy in transmission a1 T1 Γ1 a1 S 21 b1 DUT S 11 S 22 S 12 b2 a2 Γ2 T2 b2 et er1 er2 er3 1. Transmission losses 2. Reflections between DUT/Port 1 3. Reflections between DUT/Port 2 4. Reflexions between the ports ex 5. Isolation Datum VNA training Titel R&S 37 Canada 37

38 Measurement accuracy (IX) Values given by the manufacturer for accuracy in transmission Datum VNA training Titel R&S 38 Canada 38

39 Measurement accuracy (X) 10 compression noise Uncertainty in db Uncertainty (db) 1 0,1 highly linear range 0, S21 Transmission Coefficient in db*) 2 21 S = 1 Γ1Γ2 (1 Γ S )(1 Γ S ) S S Γ Γ S Datum VNA training Titel R&S 39 Canada 39

40 Measurement accuracy (XI) Receiver linearity: measurement and calibration for a 1 = -10 dbm and a 1 = +10 dbm Datum VNA training Titel R&S 40 Canada 40

41 Measurement accuracy (XII) Example of the error caused by an adaptor mounted on the test port and not taken into account during calibration: Coupler directivity 40 db DUT RL 18 db Coupler directivity 40 db Adaptor ROS 1.03 Directivity of 40 db l DUT has a RL of18 db l Directivity - RL= 22 db l Error , db l RL comprised between and18.72 db Directivity with adaptor l Coupler 40 db ρ = l Adaptator : ROS 1.03 ρ = l New directivity = 32 db ρ = Directivity of 32 db l DUT has a RL of18 db l Directivity - RL = 14 db l Error + 1.6, db l RL comprised between 16.4 et 19.9 db Coupler directivity 40 db Adaptor ROS 1.03 DUT RL 18 db Datum VNA training Titel R&S 41 Canada 41

42 Measurement accuracy (XIII) l A possibility to take into account the adaptor on port 1 is to use deembedding (specifications of the imperfections of the adaptor) l Works well for low losses l Limitations: Mesurements of a RL of 20 db through a cable, 3-dB and 10-dB attenuators Cable / adaptor 3 db att. 10 db att. Port 1 20 db load Port 1 20 db load Port 1 20 db load Datum VNA training Titel R&S 42 Canada 42

43 Measurement accuracy (XIV) Accuracy as a function of the system error correction: 0,1 db Green: Full two port (TOSM) l Corrects source- and load mismatch Red: 1-path 2-port cal l Corrects source port mismatch only Blue: Normalization l No correction for source or load mismatch Normalization and 1-path 2-port cal : l Deviation 0,05 db l Half the measurement time Datum VNA training Titel R&S 43 Canada 43

44 Types of measurements 4 principal categories: Linear measurements (S-parameters, group delay, balanced DUT, stability, switching time, ) Nonlinear measurements (n db compression point, harmonics, ) Time-domain measurements (distance to fault, transmission line impedance, ) Frequency conversion measurements (mixers, frequency multipliers, ) Important parameters for a measurement: Frequency band IF filter bandwidth => speed vs. dynamic range Power level at the input of the DUT (-20 dbm for active devices, 0 dbm for passive ones) Observed result (S, Z, Y, ratios, wave quantities ) Datum VNA training Titel R&S 44 Canada 44

45 Agenda l Calibration of the vector network analyzer l What is the purpose of calibration l Calibration methods l Measurement error l Dynamic range l Measurement Accuracy l Group delay measurement l Amplifier measurement l Linear parameters l Non-linear parameters l Time domain l Modes l Gating and filtering in time domain l Applications Datum VNA training Titel R&S 45 Canada 45

46 Group delay measurement (I) Reference plane φ ref =0 f 7 f 5 f6 f 3 f4 f 2 f φ1 t φ7 φ Ideal transmission line f 4 f 7 f Datum VNA training Titel R&S 46 Canada 46

47 Group delay measurement (II) Group delay helps to evaluate the distortion of devices Definition: the group delay corresponds to the slope of the phase of S21 compared to a linear variation τ = 1 d 360 df Arg( S21) Because discrete frequency points are defined on the VNA, a discrete differentiation (aperture) is used to compute the group delay phase f f (aperture) τ Group delay variation φ τ Slope Average group delay f Datum VNA training Titel R&S 47 Canada 47

48 Group delay measurement (III) The total delay corresponds to the propagation time Deviation from a constant group delay indicates distorsion The aperture defines the number of frequency points used to compute the group delay Datum VNA training Titel R&S 48 Canada 48

49 Group delay measurement (IV) Example 1: cable Aperture = 1 Aperture =10 Datum VNA training Titel R&S 49 Canada 49

50 Group delay measurement (V) Example 2: filter Regular SAW Datum VNA training Titel R&S 50 Canada 50

51 Group delay measurement (VI) Influence of the variation of the phase in a linear network F(t) = sin ωt + 1/3 sin 3ωt + 1/5 sin 5ωt 1,5 1 0,5 0 Tem ps 2 1,5 1 0,5 0 Temps -0,5-0, ,5-1,5-2 f Datum VNA training Titel R&S 51 Canada 51

52 Agenda l Calibration of the vector network analyzer l What is the purpose of calibration l Calibration methods l Measurement error l Dynamic range l Measurement Accuracy l Group delay measurement l Amplifier measurement l Linear parameters l Non-linear parameters l Time domain l Modes l Gating and filtering in time domain l Applications Datum VNA training Titel R&S 52 Canada 52

53 Amplifier measurement (I) Pout (dbm) Linear device: parameters only vary as a function of frequency Non-linear device: parameters vary as a function of frequency and amplitude level at its input P1dB Linear mode 1 db IP3 Dynamic Non-linear mode A device can be linear and nonlinear alternatively Po, mds Pi, mds Pin (dbm) Datum VNA training Titel R&S 53 Canada 53

54 Amplifier measurement (II) S-parameters Datum VNA training Titel R&S 54 Canada 54

55 Amplifier measurement (III) VNAs can provide gain statistics: gives insight on values of maximum gain, slope and flatness (deviation from straight line) Datum VNA training Titel R&S 55 Canada 55

56 Amplifier measurement (IV) Modern VNA capabilities for non-linear measurements: High output power (easy measurement setup) Optimized power sweep to maximize the dynamic range High power compression point of the receivers Segmented sweep with different power level Possibility to measure all S-parameters at once Power added efficiency (PAE) test set 115 db Pout = 28 dbm Datum VNA training Titel R&S 56 Canada 56

57 Amplifier measurement (V) n db gain compression point measurement carried out to assess the power range where a non-linear component is linear Typically, b2 / a1 is displayed as a function of the input power Compression point is defined as the input or output power for which the gain drops by n db (often 1 db) Datum VNA training Titel R&S 57 Canada 57

58 Amplifier measurement (VI) Simultaneous display of compression point for different frequencies Phase distortion around the compression point (AM/PM conversion) Datum VNA training Titel R&S 58 Canada 58

59 Amplifier measurement (VII) Harmonics (2 nd, 3 rd, order) are generated by the non-linearity of a device (e.g., an amplifier) Intercept points for 2 nd (IP2) and 3 rd (IP3) order are often used to evaluate the input power at which the fundamental frequency has an equal contribution to harmonics of 2 nd and 3 rd order (pure mathematical concept) Often measured using a spectrum analyzer Datum VNA training Titel R&S 59 Canada 59

60 Amplifier measurement (VIII) Intermodulation setup Datum VNA training Titel R&S 60 Canada 60

61 Amplifier measurement (IX) Intermodulation product Datum VNA training Titel R&S 61 Canada 61

62 Agenda l Calibration of the vector network analyzer l What is the purpose of calibration l Calibration methods l Measurement error l Dynamic range l Measurement Accuracy l Group delay measurement l Amplifier measurement l Linear parameters l Non-linear parameters l Time domain l Modes l Gating and filtering in time domain l Applications Datum VNA training Titel R&S 62 Canada 62

63 Time domain (I) Time domain reflectometry (TDR) often gives a clearer insight into the characteristics of the DUT A short rise time pulse is used at the input of the DUT, any impedance discontinuities will cause some of the incident signal to be sent back towards the source. Using a VNA, wave quantities results can be filtered and mathematically transformed in order to obtain the time domain representation (virtual pulse / step) Applications: Distance-to-fault in connectors, transmission lines and circuit boards (telecoms, aviation wiring, etc); Semiconductor failure analysis (non-destructive method for the location of defects in semiconductor device packages) Moving the reference plane across unknown irregularities; Removal of unwanted signals in multipath propagation; Calibration optimization Datum VNA training Titel R&S 63 Canada 63

64 Time domain (II) Time domain vs. frequency domain: Port 1 cable 1 transition cable 2 Match S11= f (freq) FFT -1 S11= f (time) Datum VNA training Titel R&S 64 Canada 64

65 Time domain (III) To compute the time domain response, the analyzer uses the chirp z- transformation that is an extension of the (inverse) Fast Fourier Transform (FFT). Compared to the FFT, the number of sweep points is arbitrary (not necessarily an integer power of 2). The following properties of the Chirp z-transformation are relevant for the analyzer settings: The frequency points must be equidistant. The time domain response is repeated after a time interval which is equal to t = 1/ f, where f is the spacing between two consecutive sweep points in the frequency domain. t is termed measurement range (in time domain) or ambiguity range. Datum VNA training Titel R&S 65 Canada 65

66 Time domain (IV) The analyzer can emulate two different types of responses: The impulse response corresponds to the response of a DUT that is stimulated with a short pulse. The step response corresponds to the response of a DUT that is stimulated with a voltage waveform that transitions from zero to unity. The two alternative responses are mathematically equivalent; the step response can be obtained by integrating the impulse response: The step response is recommended for impedance measurements and for the analysis of discontinuities (especially inductive and capacitive discontinuities). The impulse response has an unambiguous magnitude and is therefore recommended for most other applications. Datum VNA training Titel R&S 66 Canada 66

67 Time domain (V) l Impulse vs. step Substrate Trace (Micro strip line) Via stimulus Reflection time time Datum VNA training Titel R&S 67 Canada 67

68 Time domain (VI) f fstart fstop f In band pass mode, the time domain transform is based on the measurement results obtained in the sweep range between any set of positive start and stop values. The sweep points must be equidistant. No assumption is made about the measurement point at zero frequency (DC value). The time domain result is complex with a generally undetermined phase depending on the delay of the signal. Datum VNA training Titel R&S 68 Canada 68

69 Time domain (VII) In low pass mode, the measurement results are extended towards f = 0 (DC value) and it is assumed that the negative frequency response is the conjugate of the positive. f fstart fstop f Complex conjugate of measured values Interpolated values Measured values Together with the DC value, the condition of equidistant sweep points implies that the frequency grid must be harmonic. Due to the symmetry of the trace in the frequency domain, the time domain result is harmonic. Datum VNA training Titel R&S 69 Canada 69

70 Time domain (VIII) Harmonic grid: All frequencies must be an integer multiples of the frequency step f The first frequency is f = 0 The second frequency is f 1 = f A set of K frequencies is required between f = 0 and the minimum frequency of the VNA f min (determined through interpolation) Time resolution: Band pass mode: Low pass mode: t t = = f 2 stop f 1 f start 1 + f + f 1 2 stop f stop f stop 1 f start Datum VNA training Titel R&S 70 Canada 70

71 Time domain (IX) Pass band vs. low pass modes: Datum VNA training Titel R&S 71 Canada 71

72 Time domain (X) l Example: measurement of a short circuit Band pass Low pass Datum VNA training Titel R&S 72 Canada 72

73 Time domain (XI) l Real scale: Short Open Datum VNA training Titel R&S 73 Canada 73

74 Time domain (XII) Natural limitations: Frequency domain Time domain 1 FFT -1 DC f 8 Pulse response 1 FFT -1 Sin x/x DC F Stop f x = π t / fspan Datum VNA training Titel R&S 74 Canada 74

75 Time domain (XIII) Finite bandwidth of the VNA limits the resolution in time domain Side lobes reduce the dynamic range Optimization of the time domain response: Use of windowing Trade-off between dynamic and resolution Datum VNA training Titel R&S 75 Canada 75

76 Time domain (XIV) l Effect of windowing Datum VNA training Titel R&S 76 Canada 76

77 Time domain (XV) Aliasing: Sampling in the frequency range causes aliasing in the time domain F 1 No.of freq.points 1 1 t = = Ambiguityrange = 3e8 f F f Frequency x = Continuous data f Sampling Sampled data FFT -1 FFT -1 FFT -1 Time x = t t Datum VNA training Titel R&S 77 Canada 77

78 Time domain (XVI) l The resolution enhancement factor improves the resolution without increasing the upper frequency l The frequency performance (max frequency) of the connectors, cables and PCB will be not affected Datum VNA training Titel R&S 78 Canada 78

79 Time domain (XVII) l VNA: 8.5 GHz stop frequency l Window: Rectangle Factor Datum VNA training Titel R&S 79 Canada 79

80 Time domain (XVIII) l DUT: PCB Board with micro strip line at different impedances, Er ~ 3, SMA Connector and FarEnd SMA Connector terminated l Schematic of the DUT: Z 50 Ohm Z 75 Ohm Z 25 Ohm Z 40 Ohm 50 Ohm Γ 0.2 Γ -0.5 Γ Datum VNA training Titel R&S 80 Canada 80

81 Time domain (XIX) 3,50E-01 3,00E-01 ZVA: Start: 10 MHz - 20 GHz ZNB: Start 10 MHz - 8 GHz, REF: 2.5 fstep: 10 MHz 2,50E-01 Reflection Factor [U] 2,00E-01 1,50E-01 1,00E-01 5,00E-02 0,00E+00-2,00E-09 0,00E+00 2,00E-09 4,00E-09 6,00E-09 8,00E-09 1,00E-08 1,20E-08 time [ns] Datum VNA training Titel R&S 81 Canada 81

82 Time domain (XX) l Gating functionality can be used to suppress unwanted reflections l Gating will be applied to time domain mode whereas Windowing will be applied to frequency domain l Two different types of gating are available: l Band pass mode l Notch mode l Gated time domain measurements can be re transformed into frequency domain Datum VNA training Titel R&S 82 Canada 82

83 Time domain (XXI) l Example: gating e.g. Damaged connector Datum VNA training Titel R&S 83 Canada 83