The Sources of Systematic Error for a Full 2-Port S-Parameter VNA The VNA directional couplers (some VNAs use bridges, but the concept is the same) are essential to VNA operation. Therefore, the full two-port error model includes six terms for the forward direction and six terms (with different data) for the reverse direction for a total of 12 error terms. A 3.5 mm male-female adapter is used during calibration for the thru connection and is replaced by a female-female adapter with similar properties for the measurement. Full Two-port Calibration The example shown in Figure 11 calculates the measurement error after a two-port calibration and requires a vector network analyzer capable of measuring S parameters. http://redstart.net/error-correction/hamming-code-1-bit-error-correction.html
This method uses a thru adapter that has the same connectors as the noninsertable DUT. (This adapter is sometimes referred to as the calibration adapter.) The electrical length of the adapter In noncoaxial applications, TRL calibration achieves better source and load match corrections than TRL*, resulting in less measurement error since mismatch ripples are reduced. A spectrum analyzer with an amplitude accuracy of ±2 dB may not exactly characterize the amplitude of a filter like a VNA with an amplitude accuracy of ±0.1 dB does. Estimating Measurement Uncertainty Table I Error Removed with Network Analyzers Calibration Type T/R (one port) S Parameter (two ports) Reflection Reflection Tracking yes yes Directivity yes yes Source Match yes yes
Sign Up! This process makes the effective load match of the analyzer 28.7 dB (approximately a 10 dB improvement). If I turn arround the DUT so I can do S22 and S12 the same way. A device of this type is said to be insertable.
Systematic errors, as shown in Figure 2 , are caused by imperfections in the test equipment and test setup. The worst-case measurement errors for the filter have been reduced to approximately ±0.5 dB for reflection measurements and ±0.05 dB for transmission measurements. OK PRODUCT Order status and history Order by part number Activate a product Order and payment information SUPPORT Submit a service request Manuals Drivers Alliance Partners COMPANY About National Instruments Events Solt Calibration Equations It has the same type and sex connectors on each port or a different type of connector on each port, such as 7/16 at one end and SMA on the other.
Summary VNAs are exceptionally accurate and repeatable instruments when you implement proper measurement techniques and user calibration. Two Port Error Correction Many SOLT calibration kits contain a set of high-quality RF adapters with similar electrical length and RF characteristics. VNA Sources of Error User calibration accounts for 12 sources of systematic errors in a VNA. http://www.ni.com/tutorial/14114/en/ The effectiveness of these procedures is demonstrated in the measurement of high frequency components such as filters.
Measuring S11 of the short, open, and load on the Smith chart and measuring S21 of the thru connection is one way to approach this. Solt Calibration Procedure Get access topremium content and e-newsletters by registering on the web site. Periodically using verification standards is one way to gauge your need for user calibration. Ideally, measurement systems would be perfect and provide completely accurate measurements.
The effect of error correction on data can be dramatic, as shown in Figure 1 . Another benefit is that the automatic calibration module can be fitted with a variety of connector types and sexes, so you can use an assortment of device connections. 1 Port Error Correction Automatic Calibration In recent years, automatic calibration modules, such as the one shown in Figure 6, have become a popular alternative to manual techniques such as SOLT and TRL. Error Correction Term Interpretation TRL calibration, when properly implemented, can be extremely accurate, which is helpful because SOLT standards in a connectorless environment are much more challenging than TRL standards.
A solid-state calibration solution also is available that makes two-port calibration fast, easy and less prone to operator errors. this contact form Please tell us why. Terms such as match and directivity require vector measurement capability. The examination of these systematic errors highlights the importance of vector correction. Positive Error Correction Term
This type of error correction requires a network analyzer capable of measuring (but not necessarily displaying) phase as well as magnitude, and a set of calibration standards with known, precise electrical Summary of SOLT Calibration Attributes Back to Top 5. In coaxial applications, SOLT usually is the preferred calibration technique. have a peek here Your cache administrator is webmaster.
TRL does not require well-defined, connectorized calibration standards. Solt Calibration Method The mathematical equations used to derive the actual S parameters are such that each S parameter is a function of the other three S parameters. For example, Figure 4 shows a measurement of the input match of a filter after a one-port calibration has been performed.
If no DUT is available or if the DUT will be tuned (which changes its port matches), then Z0 terminations should be placed on each network analyzer test port for the The rate of drift determines how frequently additional calibrations are needed. Some of the errors are random errors, such as noise, stability and connector repeatability, which must be treated in a statistical manner.Controlled Vocabulary Termserror correction codes; network analysers; S-parameters Get PDF Network Analyzer Calibration Tutorial The bottom line is if you use an adapter during calibration, you must substitute a similar adapter during the measurement.
When making a filter transmission measurement using only response calibration, the first step is to make a thru connection between the two test ports (with no DUT in place). If adapters cannot be avoided, the highest quality types (with low SWRs) are always the best choice to reduce system directivity degradation. A simple error-correction technique such as response calibration removes the overall loss and frequency-response error. http://redstart.net/error-correction/forward-error-correction-tutorial.html These three error terms are derived from a general equation that can be solved in terms of three simultaneous equations with three unknowns.
Next is the load and source impedance match at the input and output of the device, respectively. This condition reduces the measurement error to approximately ±0.45 dB and the total measurement uncertainty to approximately ±0.67 dB (compared to ±0.85 dB for the filter). This process provides a normalized measurement by storing a reference trace in the network analyzer's memory. Over time, you develop a sense for the required user calibration intervals.
In production testing, these errors easily could cause filters that met specification to fail, while filters that did not meet specification could pass. Either layout makes connection to the test ports quite simple. These steps can be summarized as prepare, practice, calibrate, and perform: Prepare Warm up VNA for proper amount of time Place VNA in a stable environment Use high-quality adaptors, cables, and To be consistent with the next example, the effect of the directivity error signal also is included.
You can also subscribe to Microwave Journal magazine. However, the process requires more calibration standards and more measurements than needed for response calibration. Calibrations are also shown for those cases requiring coaxial adapters to connect the test equipment, DUT and calibration standards. Show 1 comment1 ReplyNameEmail AddressWebsite AddressName(Required)Email Address(Required, will not be published)Website Addressam95405 Mar 28, 2014 9:31 AMMark CorrectCorrect AnswerNo S21 phase information on N9912A.
The system returned: (22) Invalid argument The remote host or network may be down. The resulting difference between the known and measured values is used with a set of calibration equations to compute the correction factors. For example, with a coupling factor of 20 dB, the power measured in the coupled arm of a signal traveling in the forward direction is equivalent to the power in the Table 1 summarizes some of the attributes of the SOLT calibration method.