The additional steps can lead to potential process errors as you need to measure and replace standards multiple times. Swept frequency reflection measurement example of an antenna. If you consider a component that is used in a smartphone, there may be billions of components made each year. There are several types of VNA calibration standards used in the user calibration depending on the type of calibration method. Among RF and microwave test equipment, VNAs have unique calibration techniques. All calibrations performed in the field are traceable to NIST, The National Institute of Standard and Technology and are performed in accordance with documented and controlled procedures. In manufacturing applications, RF components or devices are assembled and tested based on a certain set of specifications. This is more accurate than polynomial characterization but not quite as accurate as an electronic calibration using an Automatic Calibration Module (ACM). These provide an automatic calibration that is very accurate and less prone to human error by reducing calibration to a single set of connections. Among them Short-Open-Load-Thru (SOLT), Short-Open-Load-Reciprocal (SOLR), Thru-Reflect-Line (TRL), and Line-Reflect-Match (LRM). RF network analyzers can be used for a variety of applications, such as characterizing filters, amplifiers, and impedance matching networks; measuring noise figure and gain; and troubleshooting RF circuits. Now, it is easy to understand why VNAs have helped to make many modern technologies possible. Multiport error correction removes systematic errors for the measurement, but requires a complex calibration process where calibration standards must be connected to all possible combinations of ports. March 28, 2023 Calibration corrects certain errors within the VNA and those added by connectors and test cables. TIME DOMAIN MEASUREMENTS Now, it is easy to understand why VNAs have helped to make many modern technologies possible. 4643 0 obj <>stream S-parameters are defined as ratios of signals coming from various ports relative to this reference. However, they add tremendous value by greatly simplifying the calibration process, while providing highly accurate results. Figure 3 shows a range of example applications that exist today with the help of VNAs. This These S-parameters follow the same theory and are ratio measurements between each of the specified ports. This phenomenon is called aliasing. This can be the most critical requirement for high volume manufacturing applications. The SA w/TG does a good job for 1-port reflection measurements and can perform error correction as well. It is not possible to make accurate reflection measurements lower than the Load uncertainty. If we start with the Outside View, a VNA typically has two or more ports that simply connect to the DUT - either directly or with the use of cables and adaptors. The portion of the input signal that is reflected is measured with a receiver connected to Port 1 inside the VNA. We have very accurate Platinum Resistance Thermometers as well as high accuracy humidity standards. This could be a base station cable running from the base station subsystem to its antenna. As previously discussed, the VNA measures both magnitude and phase, which means that the user calibration performs a vector error correction. VNA Cal Kit File Types About VNA Cal Kits and Firmware Upgrades Procedures How to Create a New Cal Kit from an Existing Cal Kit Creating Custom Calibration Kits using a New Connector Family Note: Although the User Interface is changed, the existing remote commands can still be used to modify Cal Kits. Therefore, the wider the frequency span, the greater the ability the VNA has to distinguish between closely spaced discontinuities. The process of calibration requires the measurement of known calibration standards. Individual standards offer excellent accuracy and offer flexibility for a variety of test setups. Types of VNA measurement error. And due to its unique user calibration, the VNA is one of the most accurate RF test instruments available. endstream endobj The portion that is emitted from port 2 is measured by the VNA receiver on Port 2 (b2 ). NEW - SN5090 9 GHz Multiport VNA Solution up to 16-Ports, New Interactive Video for Removing Fixtures from Component Measurements, 50 Ohm Frequency Extension System to 330 GHz. and Arz, U. This factory calibration is similar to the factory calibration performed on a spectrum analyzer with a tracking generator. Specifying Calibration Standards and Kits for Keysight ~zWRGO#wnpOs1`(yvM>.D>N^-E*na71K7L.E5! Calibration In addition, while all DUTs have a given operational frequency, for some DUTs you may need to consider harmonic frequencies as well. to a 2-port 2-path VNA, the DUT can be connected to either port in either direction because the instrument has the capability of reversing the signal flow so that the reflections at both ports (S11 and S22), as well as the forward and reverse transmissions (S21 and S12), can be measured. Available 6:00 AM 5:00 PM PST, Available 6:00 AM 5:00 PM (PST) Business Days, Contact us with comments, The downside is that it requires many connections to be made. For these measurements, the frequency is held constant while the output power is incrementally stepped across a defined power range. If only an S21 or transmission measurement is needed, you could use only a thru standard. By providing a known stimulus signal to the device under test or DUT, and multiple receivers to measure the response, the VNA forms a closed loop, allowing it to measure the electrical magnitude and phase response of components very accurately. A wide variety of measurements can be made from this including S-parameters, individual incident and reflected waves (e.g. The amount that the test setup drifts over time determines how often your test setup needs to be recalibrated. Typically, an electronic calibration standard is the most expensive calibration method available. Theoretically speaking, S-parameter theory can be applied to networks with an infinite number of ports. For example, if you only require an S11 or reflection measurement, you may use either an open or a short to measure the test setup response. Vector Network Analyzer Calibration Standards CALIBRATION STANDARDS The method for calibrating is as follows: Open, connect the 50Ohm cable, soldered to the PCB to the VNA and disconnect the antenna from the 50Ohm cable. Page 2 Contents 7 THRU Insertable thru standard Type N (50) FEMALE Type N (50) MALE 0 999000 0.00E+00 0.7 This vector information is what allows for complete device characterization. The most common reflection S-parameter measurements are S11 and S22 (Sxx for greater than 2-ports). The S21 measurement indicates the passband bandwidth performance as defined by its 6 dB response. To calibrate a 1-port VNA you need three sets of reference measurements: open, short, and terminated in your characteristic impedance (e.g. NOW OPEN: CMT EU Office in Paphos, Cyprus! Instead of sweeping frequencies, VNAs may also sweep the stimulus signals output power level. The two standards should appear as in Figure 5 and Figure 6, and should not be a dot. The Short is modeled as a delay from the connector to a small parasitic inductor. Tektronix designs and manufactures test and measurement solutions to break through the walls of complexity, and accelerate global innovation. The maximum frequency span is set by the user and may be defined by either the frequency range of the VNA or the viable bandwidth of the DUT. e\i$ s9/ P+8GpaF%^bDK>V=j kI.FxA;Gq|j,H%K]ZQoHJy2}zvPRH:%z7xst*j(T4[N Ic]+0k|@:d@=YF@+#4s'\O1A9p-na06InuT^I*]ZCB~^4AcT-J(xFWTe~! On the receive side, how effective is the duplexer in providing isolation between the transmit and the receive signal? S12 is the reverse transmission coefficient through the DUT and is the ratio of b1 over a2 . Basically, it ensures that the output signal meets the specs and that input signals will be represented accurately. At the time, only the 6 GHz calibration kit was available, so the data only extends to 6 GHz. The point when the amplifier output deviates from the linear expectation by 1dB is referred to as the 1 dB compression point (Figure 17). Today, VNAs are used in a wide range of RF and high frequency applications. Construction Testing: Density - State of Michigan There are several calibration methods. WebThis topic describes the Keysight vector network analyzers (VNA) implementation of the NIST Multiline Thru Reflect Line (TRL) calibration algorithm. For example, a 4-port VNA would have 16 S-parameters: from S11, S12, S13, S14, S21 . Instead of specifying a Thru in the calibration kit definition, choose Unknown Thru as in Figure 3. Among RF and microwave test equipment, VNAs have unique calibration techniques. FIGURE 10. For the sake of simplicity, it shows the source coming from Port 1, but most VNAs today are multipath instruments and can provide the stimulus signal to either port. VNA CALIBRATION METHODS WebYou can request repair, RMA, schedule calibration, or get technical support. This center is a more accurate 50 ohms, as accurate as the characteristic impedance of the air-line, which can be very precise with good machining. As well explain later, this is determined by using a VNA to measure the return loss or VSWR of the antenna. An official website of the United States government. In the Reverse case, Port 2 is transmitting the a2 signal and a matched load is applied to Port 1 (a1 = 0). Next, there's the 2-port one path method which is more accurate, but has fewer connections than a full 2-port two path calibration. Finally, we'll review typical VNA measurements such as These may be stand-alone devices and units that are incorporated in an entire system. A third source of error is drift error, which relates to measurement drift over time. The calibration standards can be physically realized in several different ways (Figure 12). A wide variety of measurements can be made from this including S-parameters, individual incident and reflected waves (e.g. 4641 0 obj <> endobj Others may be new to RF testing and not familiar with either. The portion that is emitted from port 2 is measured by the VNA receiver on Port 2 (b2 ). Low-level Instrument/Sensitive and Specialty Instruments, Need help on product selection? Advanced RF Calibration Techniques We also have the capability to Calibrate Temperature Controllers, Over Temperature Controllers and Chart Recorders. If the Short or Open standard is reattached to a port after calibration is completed, the result must look like what is shown in Figure 5 and Figure 6. This enables designers to better understand DUT performance when it is placed into a subsystem. VNAs test component specifications and verify design simulations. This allows for the DUT or calibration standard to be the only change between calibration and measurement. Spectrum analyzers are the instrument of choice when measuring digitally modulated signals. Calibration Standards Calibration In other words, at the frequency where the first Line is 155 long, use a second line which is only 20 long at this same frequency. After calibration, and if measured over a wide frequency range, re-installing the Short or Open should produce this arc. Dynamic range is the measurable attenuation range from max to min for a specified frequency range (Figure 6b). We also have a variety of Temperature Recorders to perform long-term oven surveys. Active components, such as amplifiers, converters and mixers may need to be tested at their harmonic frequencies which are 2 to 5 times operational frequency. The most common calibration standard set is referred to as Short, Open, Load, and Thru (SOLT). FIGURE 18. A Thru with unknown characteristics may be used instead as long as its S12 is equal to its S21 (reciprocal response). Before you can make any measurements with the VNA, you must calibrate it to reduce errors that can affect the measurement. x[@P EsB$B%4!alkfYQNw9r%Oyzo&L1gk6l Swept frequency measurements may also measure reflections of the stimulus signal that are incident on the DUT, but are reflected as opposed to being transmitted through the DUT. In some calibration kits, the data on the male connector is different from the female connectors, so the user may need to specify the sex of the connector within the user interface of the VNA prior to calibrating. S-parameters are defined as ratios of signals coming from various ports relative to this reference. The return loss can be better than 48 dB to 50 GHz. Spectrum analyzers are typically used to measure unknown signals, which may be over the air via an antenna or the output of a component. A3M+<9HWZ+sFW4vKjfMQ"Lk U.c~TMm:YN u3lS( I1$3vsf 02U^0T[H 4n GI_}M&=MbAcL#' Z9[iW:hF-0T@4fbiB#1e7ME B? 4649 0 obj <]>>stream PFAS Merit Laboratories, Inc. You need to calibrate for through (Both cables connected) Open/Short/Load (Each Cal standard hooked up to the end of each cable) Isolation (Both cables terminated in 50 Ohms. The Thru can have zero length, as in the case where the test cables have connectors which mate directly, or it can be a short length of transmission line. There are random, drift, and systematic errors that make VNA measurements inaccurate. By removing the influence of the accessories, the user calibration allows for the exact measurement of the DUT performance alone. Some VNAs are capable of using inverse Fourier transforms to convert swept frequency measurements into the time domain. The benefit is fewer connections during calibration. The time domain measurement locates the physical distance to the different adapters or potential discontinuities in the cable, which helps locate problem areas or faults. WebVector Network Analyzer Calibration Kit Standards Definitions . That way, if the Thru standard is somewhat degraded or the connectors arent perfectly clean, it wont matter. The point when the amplifier output deviates from the linear expectation by 1dB is referred to as the 1 dB compression point (Figure 17). In fact, it can be said that the VNA has been used over the years to help make all the networks mentioned above possible. The true multiport VNA can provide a stimulus signal to each of the ports. The Short will be a plate covering the waveguide output, and the Open will be affected by adding a 90 shim in front of the Short to create a 180 phase shift.