Low-cost, professional-grade 6 GHz and 8.5 GHz VNAs for both lab and field use
PicoVNA 2 and 3 present standard VNA measurement and calibration simply, intuitively and with efficient usage at their heart. The software offers a comprehensive range of measurements and plot formats in its one, two or four user-configurable measurement channels. All the standard vector network analyzer functions can be seen at a glance.
The PicoVNA 2 and 3 software supports a comprehensive range of calibration modes to address single or dual-port workload with male, female or mixed gender interfaces, all with best achievable accuracy (least uncertainty). In some instances only a single calibration kit may be required.
As you would expect, the Pico calibration kits are individually serial-numbered and supplied with S-parameter data. This standard-form data is a traceable and accurate record of measured errors for the calibration kit. It can be loaded into the software, which will correct for these errors and those of the instrument during a calibration.
Alternatively, you can use a third-party calibration kit whose ‘model’, electrical length, parasitic values and polynomial coefficients you can enter into the software and then save in Pico .kit format. Where a third party has supplied a calibration kit S-parameter data file, please ask us about the possibility of conversion to Pico format.
As for any vector network analyzer, for best accuracy a calibration is performed before a measurement with the same sweep span and frequency steps as the measurement. If, however, a change of sweep settings is necessary for a measurement, the PicoVNA 2 and 3 software will for convenience interpolate its corrections to the new sweep settings.
An enhanced isolation calibration setting is available for optimum dynamic range when using resolution bandwidths below around 1 kHz.
Reference plane extension (offset) allows you to shift the measurement reference plane away from the point established during calibration. This is useful in removing the path length of assumed ideal interconnecting , connectors cables or microstrip lines from measurements.
The PicoVNA software allows independent reference plane extensions on each of the measurement parameters (S11, S22, S12 or S21), either as an automatic re-reference or by manual entry. Independent extensions allow, for example, different extensions on the two ports for S11 and S22 and then thru-line normalization for S21 and S12 transmission comparison with equivalent length thru-line.
When it is unsafe to assume the above ideal interconnecting connectors cables or microstrip lines; for example to achieve greater accuracy or to remove known imperfections in a test setup, we can choose instead to de-embed the interface networks on each measurement port. The PicoVNA software simply requires a full Touchstone .s2p file for the embedded interfacing network on each port. Likewise, defined networks can be embedded into the measurement to achieve a desired simulated measurement. As for a calibration, best accuracy will be achieved when the embedding network is defined at the same frequency points as the intended measurement. Unusually for a vector network analyzer, the PicoVNA software will interpolate where necessary and possible.
System measurement impedance (default 50 Ω) can be mathematically converted to any value between 10 Ω and 200 Ω. The PicoVNA software also supports the use of external matching pads and calibration in the new impedance using a calibration kit of that impedance.
Time domain reflectometry is useful in the measurement of a transmission line; in particular the distance-to-fault location of any discontinuity due to connectors, damage or design error. To achieve this, the PicoVNA software determines from its frequency domain measurements the time domain response to a step input. Using a sweep of harmonically related frequencies, an inverse fast Fourier transform of reflected frequency data (S11) gives the impulse response in the time domain. The impulse response is then integrated to give the step response. Reflected components of the step, occurring at measurable delays after excitation, indicate the type of discontinuity and (assuming a known velocity of propagation) the distance from the calibration plane.
A similar technique is used to derive a TDT (time domain transmission) signal from the transmitted signal data (S21). This can be used to measure the pulse response or transition time of amplifiers, filters and other networks.
The PicoVNA software supports Hanning and Kaiser–Bessel lowpass filtering on its time-domain IFFT conversions, preserving magnitude and phase, and achieving best resolution. A DC-coupled DUT is essential to the method.
The 8.5 GHz bandwidth of the PicoVNA 108 supports time-domain pulse transition times down to 58.8 ps and that of the PicoVNA 106 down to 82.7 ps.
The 1 dB gain compression point of amplifiers and other active devices can be measured using a power sweep, either at a test frequency or over a sweep of test frequencies. The VNA determines the small-signal gain of the amplifier at low input power, and then increases the power and notes the point at which the gain has fallen by 1 dB. This utility uses a second-order curve fit to determine interpolated 1 dB compression points.
AM to PM conversion is a form of signal distortion where changes in the amplitude of a signal produce corresponding changes in the phase of the signal. This type of distortion can have serious impact in digital modulation schemes for which amplitude varies and phase accuracy is important.
The limit lines facility allows six segments to be defined for each displayed plot. These can be extended to 11 segments using an overlapping technique. Visual and audible alarms can be given when a limit line is crossed. All plot formats except Smith chart and polar support limit testing. Peak hold functions are also available.
The supplied Touchstone measurement data for a serial-numbered check standard is loaded into the PicoVNA memory trace as a ‘Reference’ measurement.
With a valid, full S-parameter, full-span calibration established and the check standard connected between the test ports, the comparison utility performs a measurement. It then compares and tabulates, at each frequency point, the measurement with the stored ‘Reference’ data. Magnitude and phase difference are tabulated.
The utility combines uncertainties for the instrument and test leads (respective specifications) with measurement uncertainty and stability of the check standard (also supplied). The difference between reference and measurement is then compared with total uncertainty, giving a result of ‘pass’ (within uncertainty) or ‘fail’ (outside uncertainty).
You can save the comparison dataset for archive or analysis and a Microsoft Excel template (available for download) helps you visualize the comparison and its uncertainties.
This is a very demanding evaluation of an instrument, test leads and the calibration performed, very nearly, to the full specification of the instrument and leads. The test is designed to identify a weak process, or worn, contaminated or damaged system components that might lead to a compromised measurement. To gain a pass, correct calibration procedure must be followed, including the use of torque wrenches to make the connections at calibration and comparison measurements.
The uncertainty data provided attempts to take into account the expected variability of your measurement setups when mating the check standard with Pico-supplied PC3.5 or SMA port connectors. There is a wide variation in the quality of commercially available test cables and SMA connectors, and contamination, damage or wear can easily occur. We guarantee that the uncertainty data provided will cover your test setups only when you use Pico-supplied calibration standards, port adaptors and test leads in new condition.
Uniquely, benefiting from the fast measurement speed of the PicoVNA, save on trigger provides a fast and convenient method for capture and display of measurement data from multiple or changing device-under-test states. Think, for example, of variable attenuators, digitally configured filters, phase shifters or variable-gain amplifiers. Think also of devices under changing power supply, bias or environmental conditions, or even of a multiplexed measurement of a number of devices in the production environment. The PicoVNA can be set up to store up to 1024 triggered sweep measurements which can then be inspected, reordered and saved to disk in a number of formats. The trigger event can arrive on the external trigger input, or as a remote software trigger or a manual key press.
Captured measurement sweeps can be selected for display which, by default, shows one to four selected S-parameters across a maximum of 64 individually coloured traces, all plotted over the band of operation. The plotted sweeps can be any subset of all the captured sweeps and data can be normalized to one of the captured sweeps, which is useful for examining changes from sweep to sweep.
The plots to the right show S21 (magnitude and normalized magnitude in dB) for 16 states of a programmable step attenuator. The plot beneath and right plots S21 and S11 at a user-selected frequency of 986 MHz. Here the horizontal axis plots measurement sweep number, each in this case representing a unique state of the attenuator. All four S-parameters can be displayed simultaneously in this way on the graphs. Using a hardware external trigger and maximum resolution bandwidth, all the data for these plots was captured within 1 second!
The captured sweep data can be saved to disk in a number of formats, including Touchstone®, for use with third-party applications. Data can be saved grouped by s-parameter, for example. The file list on the right shows the files created for the stepping attenuator. You simply enter the name Step_Attn when saving the data, and the family of files shown is automatically created. In each of these files each column contains the S-parameter data for a given sweep. The first column after the frequency column contains data from the first sweep, the second has data from the second sweep and so on.
The data can also be saved for any single frequency within the sweep range used to capture the data. There is also an option to save the entire dataset for later use.
A wide range of mixer performance and port isolation measurements can be carried out, including swept RF or IF with a choice of low or high side LO. A PicoSource AS108 or a third-party signal source is used as the external LO source, and this operates under the control of the PicoVNA 3 PC application. The software also supports a third-party USB power sensor in the characterization of port power.
|Supported USB-controlled signal sources||Supported USB-controlled power sensors|
|PicoSource AS108||Agilent / Keysight U8480, U2000|
|MiniCircuits SSG-15G, SSG-6000, SSG-6001||Rohde & Schwarz NRP8S, NRP8SN, NRP18S|
|TTi TGR 6000|
Contact the factory for your choice of external USB signal generator or power sensor to be considered.
Mixers can be difficult to measure accurately particularly when mixer port match is relatively poor. The PicoVNA 108 mixer measurement calibration includes the option of VSWR error correction. This reduces the conversion loss measurement uncertainty as typically shown in the diagram.
Conversion loss change as a function of the input RF level is easily determined. This can be referenced either to the port power uncertainty of the PicoVNA or the user can use a third-party power sensor (above) to pre-characterize the PicoVNA 108 port power for enhanced accuracy. The 0.1 and 1 dB compression points are displayed on completion.
The PicoVNA 2 software provides an ActiveX server, allowing you to write your own software to communicate with the PicoVNA Vector Network Analyzer on Microsoft Windows platforms.
Example code is available via our GitHub organization page, including a toolbox for use with MathWorks MATLAB.
IoT, 5G, WiFi, V2X – has there ever been a bigger market explosion than the use of the antenna, and use within very challenging locations? Optenni Lab is industry-leading RF design automation software for antenna matching and RF chain performance optimization. The tool addresses multi-band, broadband, multi-antenna and tunable antenna systems and synthesizes measurement-based matching solutions in real time. In other words, Optenni Lab outputs optimized matching circuits based on live vector network analyzer measurements of antennas. Optenni Lab versions from 4.3 SP5 are compatible with the PicoVNA. The tool synthesizes optimal topologies from discrete, distributed, variable or switched component libraries against desired bandwidth and isolation targets, taking into account mutual coupling to nearby antennas. Optenni Lab automatically outputs highly complex and normally time-consuming designs. This CAD software interfaces the PicoVNA 2 control DLL directly and no further software is required.
The AWR Connected wizard for the PicoVNA brings affordable vector network measurement right into the Cadence AWR Design Environment. Component, system and subsystem measurements are available, controllable and displayed inside your simulation workspace. Real-world measurements become available for one-click transfer directly to project data files – that you can use within your simulations or for direct plot and comparison.
Design–Simulate–Implement–Measure workflow is encapsulated in a single design environment, tightly coupled for optimized speed and efficiency.
Can there be any more effective and rewarding learning experience than completing the whole design cycle? Unfortunately, the high costs of microwave network measurement have for many compromised that experience in the classroom. We believe that the more affordable PicoVNA 106 6 GHz full-function, professional-grade vector network analyzer, partnered with Microwave Office, changes the game.
Designed within Microwave Office, the PCB project design file is available to download. Students and trainers can engage at any point in the design cycle, compare simulation with real measurement, and experiment within the simulated and real environments.