Manuale d’uso / di manutenzione del prodotto 8510 del fabbricante Agilent Technologies
Vai alla pagina of 32
Agilent Specifying Calibration Standards for the Agilent 8510 Network Analyzer Application Note 8510-5B Discontinued Product Information — For Support Reference Only — Information herein, may refer to products/services no longer supported. We regret any inconvenience caused by obsolete information.
2 3 3 3 4 5 5 7 7 8 9 9 9 11 12 12 12 14 14 15 16 16 17 17 17 18 18 18 18 19 19 19 19 19 20 20 20 21 21 22 22 22 23 23 26 29 Introduction Measurement errors Measurement calibration Calibration kit Sta.
3 Introduction This product note co vers measurement calibration requirements for the Agilent 8510B/C network analyzer . All of t he capabilities described in this note also apply to the A gilent 8510.
4 The array coeff icients are computed by measuring a set of “kno wn” devices connected at a f ixed point and solving as the vector difference betw een t he modeled and measured response. The full 2-port er ror model sho wn in F igure 1 is an example of onl y one of t he measurement calibra- tions available with the 8510.
5 Standard definition Standard def inition is the process of mathematical- ly modeling the electrical characteristics (delay , attenuation and impedance) of each calibration standard.
6 T able 1. Standard definitions table T able 2. Standard class assignments.
7 Modification procedure Calibration kit modification provides the capability to adapt to measurement calibrations in ot her con- nector types or to generat e more precise error models from existing kits.
8 Define standards A glossar y of standard definition paramet ers used with t he Agilent 8510 is included in t his section. Each parameter is described and appropriate con- versions are listed f or implementation wit h the 8510. T o illustrat e, a calibration kit f or WR -62 rec- tangular waveguide (operating frequency range 12.
9 Each standard is described using the St andard Definition Table in accordance with t he 1- or 2- port model. The St andard Definition t able for a wav eguide calibration kit is shown in Table 1. Each standard type (shor t, open, load, thr u, and arbi- trar y impedance) ma y be def ined by the parame- ters as specif ied belo w .
10 It is not possible to remov e fringing capacit ance, but the result ant phase shift can be modeled as a function of frequency using C 0 through C 3 (C 0 +C l x f + C 2 x f 2 + C 3 x f 3 ,with units.
11 Note In some cases (when the phase response is linear with respect t o frequency) the response of an open can be modeled as an equivalent “incremental” length. This method will serve as a first order appro xima- tion only , but can be useful when dat a or stan- dards f or t he abo ve modeling techniques are not available.
The inductance as a function of frequency can be modeled by specifying the coeff icients of a third- order polynomial (L 0 + L 1 x f + L 2 x f 2 + L 3 x f 3 ), with units of L 0 (nH), L 1 (10 -24 H/Hz), L 2 (10 -33 H/Hz 2 ) and L 3 (10 -42 H/Hz 3 ). F or t he wav eguide example, the induct ance of the offset shor t circuits is negligible.
13 The convention f or def inition of offset delay in wav eguide requires entr y of t he dela y assuming no dispersion. F or waveguide transmission line, the Agilent 8510 calculat es the ef f ects of .
14 µ r = relative permeability constant of t he medium (equal to 1.0 in air) ε r = relative permittivity constant of t he medium (equal to 1.000649 in air) D = inside diameter of outer conduct or d .
15 Therefore, f or the WR -62 wav eguide st andard defi- nition table, of fset loss of zero ohm/sec is entered for all f our standards. Lower/minimum frequency Lo wer frequency defines t he minimum frequency at which the st andard is to be used for the purposes of calibration.
16 Upper/maximum frequency This specifies t he maximum frequency at which the st andard is valid. In broadband applications, a set of banded standards may be necessary t o pro- vide constant response. For exam ple, coaxial of fset standards (i.e., 1 / 4 λ offset shor t) are generally spec- ified over bandwidths of an octav e or less.
17 Note Mathematical operations on measurements (and display ed dat a) aft er calibration are not corrected for dispersion. Enter W A VEGUIDE int o the st andard definition table for all f our st andards. Standard labels Labels are entered through t he title menu and ma y contain up t o 10 characters.
18 S 11 A,B,C and S 22 A,B,C S 11 A, B,C and S 22 A,B,C correspond t o the S 11 and S 22 ref lection calibrations for port 1 and por t 2 respectivel y. These t hree classes are used by the Agilent 8510 t o solv e for the systematic er rors; directivity , source match, and ref lection tracking.
19 TRL Thru TRL Thru cor responds to t he measurement of the S-parameters of a zero-length or shor t thr u connec- tion between port 1 and por t 2. The Thru, Ref lect and Line classes are used ex clusively f or t he three steps of the TRL 2-PORT calibration.
20 Each adapter is specif ied as a single delay/thr u standard and up to seven standards numbers can be specified int o the adapter class. Standard Class labels Standard Class labels are entered t o facilitat e menu-driven calibration.
21 Again, cal kit labels should be chosen t o best describe the calibration devices. The “B.1” default suff ix corresponds t o the kit’s mechanical revision (B) and mathematical revision (1).
22 User modified cal kits and Agilent 8510 specifications As noted previously , the result ant accuracy of t he 8510 when used with any calibration kit is depend- ent on ho w well its standards are defined and is verified through measurement of a device with traceable frequency response.
23 Appendix A Calibration kit entry procedure Calibration kit specifications can be ent ered into the A gilent 8510 using the 8510 disk drive, a disk drive connected to the syst em bus, by fr ont panel entr y , or through program control b y an ext ernal controller .
24 Front panel procedure: (P -band waveguide example) 1. Prior to modifying or generating a cal kit, store one or both of t he cal kits in the 8510’s non- volatile memory to a disk. 2. Select CAL menu, MORE. 3. Prepare to modify cal kit 2: press MODIFY 2.
25 4. Change the class label for S 11 A: LABEL CL ASS, S 11 A, ERASE TITLE. 5. Enter the label of PSHORT 1 by using the knob, the SELECT sof t ke y and t he SP ACE soft k ey.
26 Appendix B Dimensional considerations in coaxial connectors This appendix describes dimensional considera- tions and required conventions used in determin- ing the physical offset length of calibration standards in sexed coaxial connector families.
27 Female type-N Male type-N 7 mm Coaxial connector T ype-N coaxial connector interface The location of the “calibration plane” in T ype-N standards is the outer conductor mating surfaces as shown below . Note: 1.0mm, 1.85mm and 2.4mm connectors not shown, but similar to 3.
28.
29 Appendix C Cal coefficients model Offset devices like offset shorts and of fset opens c an be modeled by the follo wing signal f low graph : Figure 1 Signal flow graph model of offset devices The offset por tion of the open or shor t, is modeled as a perfectly unif or m lossy air dielectric transmis- sion line.
30 Their first order appro ximations, R is small and G=0, are: Equation 3 Since Equation 4 F or coaxial devices.
31 then: Equation 5 Equation 6 If the Of fset delay=0, then the coeff icient of ref lection, Γ = Γ L ..
www .agilent.com/find/emailupdates Get the latest information on the products and applications you select. Ag ilent Email U pda tes www .agilent.com Agilent T echnologies’ T est and Measurement Support, Services, and Assistance Agilent T echnologies aims to maximize the value you receive, while minimizing your risk and problems.
Un punto importante, dopo l’acquisto del dispositivo (o anche prima di acquisto) è quello di leggere il manuale. Dobbiamo farlo per diversi motivi semplici:
Se non hai ancora comprato il Agilent Technologies 8510 è un buon momento per familiarizzare con i dati di base del prodotto. Prime consultare le pagine iniziali del manuale d’uso, che si trova al di sopra. Dovresti trovare lì i dati tecnici più importanti del Agilent Technologies 8510 - in questo modo è possibile verificare se l’apparecchio soddisfa le tue esigenze. Esplorando le pagine segenti del manuali d’uso Agilent Technologies 8510 imparerai tutte le caratteristiche del prodotto e le informazioni sul suo funzionamento. Le informazioni sul Agilent Technologies 8510 ti aiuteranno sicuramente a prendere una decisione relativa all’acquisto.
In una situazione in cui hai già il Agilent Technologies 8510, ma non hai ancora letto il manuale d’uso, dovresti farlo per le ragioni sopra descritte. Saprai quindi se hai correttamente usato le funzioni disponibili, e se hai commesso errori che possono ridurre la durata di vita del Agilent Technologies 8510.
Tuttavia, uno dei ruoli più importanti per l’utente svolti dal manuale d’uso è quello di aiutare a risolvere i problemi con il Agilent Technologies 8510. Quasi sempre, ci troverai Troubleshooting, cioè i guasti più frequenti e malfunzionamenti del dispositivo Agilent Technologies 8510 insieme con le istruzioni su come risolverli. Anche se non si riesci a risolvere il problema, il manuale d’uso ti mostrerà il percorso di ulteriori procedimenti – il contatto con il centro servizio clienti o il servizio più vicino.
