Search field. Contact Us. Shop Online.
Verification Methods S parameters comparison of User-Characterized and Factory-Characterized Verification Standards This method involves a user measuring pre-characterized verification devices with similar performances to their own device; i.
The measurement data is then compared to the factory-measured data and the user determines whether the calibration is valid or not, based on experience or general guidelines.
There is no clear pass-fail criteria that quantifies whether a calibration is sufficiently accurate to proceed to device measurement, or whether a calibration needs to be repeated. S-parameters Comparison of User-Characterized and Factory-Characterized Verification Standards including Measured Uncertainty Boundaries It is possible to define clear pass-fail criteria based on the use of uncertainty boundaries.
When the uncertainty boundaries measured on a verification device by the user overlaps the uncertainty boundaries measured on the same verification device at the factory, it is defined as an accurate calibration. If the boundaries do not overlap, then recalibration is recommended. Maury offers a VNA Calibration and Measurement software suite, Insight, which among other things automates this process by guiding users through the calibration validation and clearly identifies whether the calibration can be used or must be repeated.
For more information on Insight, please visit maurymw. Available Models Swipeable Content. Coaxial cal kits are available as Fixed-Load SOLT kits using polynomial equations, and as characterized device CD kits using individually characterized cal standards.
VNA Verification Kits
Insight represents a paradigm shift in the way users approach VNA calibration, validation, measurement, visualization and analysis. More information regarding Insight can be found here. Full Catalog Download or View Online. All rights reserved.Welcome, Guest.
Please login or register. Did you miss your activation email? This topic This board Entire forum Google Bing. Print Search. I'm starting with the Molex which has manufacturer-done drawings and CAD models: This is how I'm thinking of modeling the connector to determine the coefficients to enter on the VNA - hoping some metrology expert can follow along and chime in if I'm doing things right or wrong.
For the simulation, I modeled the geometry of thewithout the screw threads or center pad chamfer, but including the tiny air gap seen above where the insulation isn't flush with the housing. For the short standard, I modeled a flat plane of metal capping the end with the same dimensions as the square base.
I put this geometry through openEMS and after some trial and error the results seemed quite reasonable - the Smith chart shows them as starting at either open or short at DC and then walking clockwise along the unit circle as you'd expect as the frequency increases. It seems the calculated electrical length was a bit too long. Correcting S11 with this length rotated things into the lower half of the Smith chart. Adjusting the meshing of the simulating finer would lead to a shorter electrical length, but not quite enough to get a positive inductance L0.
So, I'm here with a few questions: 1.
Is this approach sound for modeling open and short standards? What kind of limitations are there to doing this? It seems the like the electrical length in the equations above is not critical, because if you chose a shorter length within reason!
So should I just use the length as determined from the CAD drawings I would use the length of the insulation as the transmission line length, adjusted for the dielectric and solve for the coefficients with that length?
Kirkby Microwave - manufacturers of VNA calibration kits.
That should yield more sensible inductance coefficients at least. I read somewhere it is ideal for the length of the short to be slightly longer than the open, but I'm not sure why? Ideally you would use the kit S parameters directly for calibration.
I think most proper VNA software accepts S parameter calibration kit characterization. Quote from: jmw on September 22,am. I think the decision on length depends upon where you want the reference plane to be. So using the CAD length makes sense. You are doing this correctly. Yes, it is normal to have negative values for some of the capacitance or inductance chararacterization. As long as the curve fits the actual response, you're golden.
For a commercial calibration kit, the delay is most important. The capacitance or inductance make very small differences and may not even be distinguishable below a few GHz. The curves of delay vs capacitance or inductance can be fairly different so least error will be achieved with the right choice of delay. To some extent you can trade one off against the other.Our kits are very low cost considering the technical design and the technical support you will receive. Several lower cost kits can be purchased from eBay, and other commercial companies, but we are not aware of any as well designed as ours, or sold with as much support for ours on a wide range of vector network analyzers.
Some of the eBay sellers have copied huge chunks from our auctions! All coaxial kits include both male and female components, so they are not simple male calibration kits or female calibration kits, but include both genders. Waveguide calibration kits are always genderless. Our calibration kits will not have such high accuracy as a kit from one of the big expensive manufacturers, but our calibration kits will be sufficiently accurate for all but the most demanding professional use, as well as all amateur use.
The kits are considerably more accurate than many so-called economy calibration kits, which consist of nothing more than random opens, shorts and loads. Without accurate data on the standards, these are useless. There is a lot more to designing a calibration kit than assembling an open, short and load.Having built a couple of vector network analyzers VNAsthe N2PK design and a homemade one based on the six-port concept and having also recently bought one, a venerable CI needed some known reference impedances to properly calibrate them.
These known reference impedances are called the calibration kit.
While, in principle, perfect reference impedances could be built, in practice the short, open and load are only approximations of the ideal impedances they should represent and most of the difficulty in building a calibration kit is in characterizing these imperfections; I had the opportunity to do some measurements with a lab-grade VNA, which, after a proper calibration with its own calibration kit, was used to characterize my homemade reference impedances.
This allows to obtain a sort of "secondary standards", which, considering the amateur radio use, will be of good enough quality, at least at not-too-high frequencies. To be able to use these loads as calibration standards for a VNA, they characteristics must be expressed in terms of the standards model every VNA implements; for historical and practical reasons, many VNAs need to have the calibration standards defined in terms of a simple model - only modern VNA can directly use the S-parameters of the calibration standards the so-called data-based model.
For the 1-port standards considered here the model is a lossy transmission line terminated by a defined load; the lossy transmission line characteristics are described by using the offset delayoffset loss and offset Z 0 terms, while the termination loads are defined using a frequency-dependent inductance and capacitance respectively for the short and open standards and a perfect termination for the load standard see  for all the details.
The allowable ranges for the various parameters for the HPC are summarized in the following tables:. Here is a script for GNU Octave to compute the standard models coefficients from the measured loads S-parameters. To run the script, the nonlinear optimization library NLopt and the S-parameter toolbox by Tudor Dima contact him to obtain a copy are needed. IN3OTD's web site Programs Pictures. Homemade VNA calibration kit Having built a couple of vector network analyzers VNAsthe N2PK design and a homemade one based on the six-port concept and having also recently bought one, a venerable CI needed some known reference impedances to properly calibrate them.
Механические и электронные калибровочные комплекты
Agilent Technical Forum, " Type N cal kit data needed " thread.Forums New posts Search forums. Media New media New comments Search media. Resources Latest reviews New resources Search resources. Attachment List. Log in Register. Search titles only. Search Advanced search…. New posts.
The VNA wouldn't be able to correctly measure the verification kit without calibration from a good cal kit. The reason calibration exists is to answer the question, "how do i know it's good? Then i would start over except use the non-calibrated cal kit. That way I know the VNA itself is not to blame should the verification fail.
I would say that is evidence enough, but, in addition to this, i could use a calibrated cal kit same model as UUT to cal the VNA, then proceed to measure the components from my non-calibrated kit. Is that ? Then all I have to do is relax the test limits and make it at least You might say the increased uncertainty could result in false pass components, but what does any of that matter as long as it can properly measure the verification kit components?
Any thoughts on this? BradM Staff member. Oct 18, Hello there!! Now, I first have to admit ignorance with the specifics of the process you're wanting to calibrate, so forgive any dumb questioms. You will use 3 to verify 2; then use 2 to verify 1. As far as uncertainty, are you building a budget? Have you estimated all the uncertainties in the whole process? Sorry for all the questions. Hopefully I'll can help out somehow.
Pezikon Oct 19, Hi BradM, thanks for your interest in my question. I may have said too much and that complicated my question. Your understanding of my question didn't sound quite right to me. You seemed to outline a transfer standard sort of situation and I don't think that's what it is. Also, to answer your question, I have not attempted to create an uncertainty budget nor do I intend to.Last year I made a simple vector network analyzer for measuring S-parameters of microwave circuits that I'm making at home.
Budget was very small and it was mostly a proof of concept for a low cost homemade VNA. If you don't know what a vector network analyzer is I recommend that you read the previous post first, but in short it is a test device that can be used to measure magnitude and phase of transmitted and reflected power of a circuit. For example amount of power reflected back from antenna should be low at its working frequency. While it worked and I could use it to measure one and two-port S-parameters measurement accuracy was not very good.
One port measurements worked reasonably well but the biggest problem with two port measurement accuracy was leakage between the test ports. To even calibrate the instrument I had to use an exotic term calibration that can compensate for different leakage paths between the receiver channels.
Lack of isolation between the ports was the biggest issue, but there were also many other smaller issues:. Receiver noise figure was very high since there wasn't any amplification before the mixer.
Increased noise figure resulted in noisy measurement and reduced dynamic range. Linearity of the receiver was not very good. This was partly caused by the bad choice of IF amplifier and partly because I used a balanced mixer without a balun.
Mixer is recommended to be driven with differential input, but wideband baluns were too expensive.#158: Directional Coupler Basics & how to sweep SWR of an antenna - Return Loss - VSWR
Driving the mixer with other input terminated was possible but linearity, conversion gain and noise figure suffered. At low frequencies coupling was very low and the signal to noise ratio at the receiver was not very good. At high frequencies directivity and matching of the couplers started to worsen. In theory even if the matching, directivity or leakage were high they can be corrected by the calibration. In reality there is some amount of drift and noise in the instrument that causes the vector error correction to not be exact and some amount of error shows up in the results.
There was enough drift, non-linearity and noise that there were significant errors in the measurement results even after the calibration. Microcontroller was not fast enough to do any signal processing and all the signal processing needed to be done on the PC. While the PC should be fast enough to process the samples without delaying the next measurement, in practice my code was written in Python which just wasn't fast enough to do all the signal processing without delaying the measurement.
Microcontroller was also busy with reading the ADC and didn't have time to do anything else at the same time. In total there were enough room for improvement that I wasn't be happy with the board and decided to make an improved version that tried to fix the problem points as well as I could while still keeping to cost low.The designer, Michael Knitter DG5MK, has taken feedback from users of the previous VA4 instrument and incorporated many new features in the VA5, whilst maintaining high performance and excellent value for money.
High precision instrument ideal for measurement of antennas, cables and other one port devices. A replacement for the highly successful RSP2 and RSP2pro models, this new SDR Receiver has been extensively redesigned to provide enhanced performance including additional and improved pre-selection filters, improved intermodulation performance, the addition of a user selectable DAB notch filter and more software selectable attenuation steps.
Read mor e. The FA-VA5 is a portable instrument, offering precise one port vector measurements up MHz, with up to 40 hours battery life from 2 AA batteries at a very competitive price. Assembly of the kit consists of soldering 12 through hole components and typically takes only few hours, aided by a quality 35 page full-colour Assembly and User manual. The conversion procedure should take less than 20 minutes, and is easily reversible. Recommended Product! Small dimensions 15 x 8. Add to Cart.
Please note that postal deliveries in many countries are severely disrupted and subject to delay. To avoid disappointment, please check the current position for international post from the UK before placing your order.
Courier shipping service currently appears to be operating in many countries without significant delays. Special Offer - Lower price! Read mor e New!