WHY VNA 2.2.2

Advanced RF measurement, calibration, analysis and signal generation for LiteVNA and compatible NanoVNA V2 instruments.

Free software for the amateur radio community.

WHY VNA is a standalone Windows application designed to bring advanced vector network analysis to affordable VNA hardware.

It combines an instrument-style interface with professional measurement techniques, advanced calibration, S-parameter analysis, calibration-kit characterization, fixture de-embedding, trace comparison and comprehensive diagnostic tools.

The goal is simple: to make advanced RF measurements accessible to radio amateurs, experimenters and electronics enthusiasts without the need for expensive commercial software.

WHY VNA is developed as a personal, non-commercial project and is provided free of charge to the amateur radio community.

The project has evolved considerably, with rapid development during 2026 supported by AI-assisted programming and code review. However, actual RF measurements, independent reference instruments and feedback from experienced users remain central to the development process.

What's new in WHY VNA 2.2.1?

Version 2.2.1 consolidates several significant improvements to the measurement engine, calibration workflows, user interface and diagnostic capabilities.

Measurement and performance improvements

• Improved USB/FIFO communication and more efficient graphical updates.

• Host-side optimizations permanently enabled without additional user settings.

• Improved two-port measurement workflows, including guided forward and reverse measurements.

• More consistent trace scaling and display behaviour.

• Improved measurement handling, stability and usability.

The optimizations reduce unnecessary PC-side processing without changing the instrument's IF integration, averaging, measurement data or calibration calculations.

The actual sweep speed remains primarily limited by the instrument's internal acquisition and signal-processing hardware.

Advanced calibration and measurement accuracy

Recent developments include:

• Advanced 12-term two-port error correction.

• Improved SOL and SOLT calibration workflows.

• Calibration-kit characterization and verification.

• Support for detailed OPEN, SHORT and LOAD models.

• Improved handling of calibration reference planes and adapters.

• Additional tools for evaluating calibration quality and repeatability.

• Continued improvements based on independent measurements and user feedback.

Accurate calibration remains one of the most important aspects of WHY VNA.

The software provides the tools needed to investigate measurement uncertainty, calibration standards and fixture effects rather than simply displaying apparently precise results.

New measurement diagnostics

WHY VNA 2.2.1 includes additional diagnostic workspaces:

VNA Timing Analysis

Measures instrument sweep performance at different point counts, IF settings and channel configurations.

USB PLL / Guard Diagnostics

Investigates sweep-time dependence on frequency step size and channel selection.

Dual-Channel Complex Validation

Compares single-channel and two-channel measurements using actual complex measurement data, including amplitude, phase and repeatability.

12 MHz Stability Analysis

Investigates frequency-dependent amplitude and phase variations observed during repeated measurements on the LiteVNA67.

During development, increased measurement variation was identified near certain multiples of 12 MHz. The phenomenon was reproduced in several frequency ranges and affected both S11 and S21.

The physical cause has not yet been established. The analysis tools help investigate this behaviour but do not apply unverified corrections to measurement data.

These diagnostic features are intended for users who want to investigate the actual performance and limitations of their instruments.

VNA measurement and analysis

WHY VNA provides a comprehensive measurement environment for RF components, antennas, filters, cables and networks.

Measurements and display

• S11 and S21 measurements.

• S12 and S22 analysis through supported reverse two-port measurement workflows.

• Magnitude, phase and group delay.

• Return loss, SWR, impedance and admittance.

• Smith chart, admittance Smith chart and polar display.

• Four independent markers with search, tracking and delta functions.

• Continuous and segmented sweeps.

• Trace memory, trace mathematics and sweep history.

• Waterfall display and limit testing.

• Measurement comparison and detailed analysis tools.

Reverse S-parameters require appropriate reverse measurements and calibration. They are not assumed to be independently measured simply because four S-parameters can be displayed.

Calibration, kits and fixtures

• SOL and SOLT calibration with reusable profiles.

• Advanced two-port error correction.

• Calibration-kit definitions, characterization and verification.

• Calibration through adapters and reference-plane management.

• Port extension and time-domain gating.

• S2P fixture de-embedding.

• Symmetric 2×-Thru fixture characterization.

• Extraction of electrical left and right fixture models.

• Fixture-quality checks and frequency-range guidance.

At microwave frequencies, OPEN and SHORT standards are not electrically ideal.

WHY VNA therefore supports realistic calibration-kit models and tools for evaluating whether the calibration and fixture corrections produce physically meaningful results.

Antennas, filters, cables and components

WHY VNA includes dedicated measurement tools for a wide range of applications.

Antennas

Resonance frequency, SWR, return loss, impedance and bandwidth.

Filters

Insertion loss, rejection, bandwidth, group delay and frequency response.

Cables

TDR-style cable length, distance-to-fault and discontinuity analysis.

Passive components

Resistors, capacitors, inductors, crystals and resonators, including one-port and supported two-port measurement configurations.

Amplifiers and active devices

Gain, return loss, bandwidth, gain flatness and relative gain compression.

Absolute P1dB is not reported unless the available RF power has been independently calibrated.

Noise figure requires appropriate noise-measurement hardware, while IIP3 and OIP3 require a suitable calibrated two-tone measurement setup.

WHY VNA does not estimate these parameters from insufficient measurement data.

Experimental WHY-Spiced signal generator

WHY-Spiced was introduced during the 2.1 development series.

It is an unofficial experimental modification of LiteVNA67 firmware v1.4.10, developed to investigate additional capabilities of the instrument's internal RF synthesizer.

The modification introduces USB control of native CW frequency generation without repeatedly executing a normal VNA measurement sweep.

When the compatible experimental firmware is installed, the Signal Generator workspace supports:

• Native USB-controlled CW frequency selection.

• Experimental frequency commands up to 12 GHz.

• Single and continuous frequency-stepped sweeps.

• Control of internal hardware attenuation.

• Saved RF output-power calibration profiles.

• Frequency-dependent power compensation.

• Automatic selection of achievable output levels.

• Additional user-selected attenuation.

Calibrated output power

WHY VNA uses measured output-power profiles to determine which RF levels can be maintained across the selected frequency range.

Standard output levels, such as −10, −20 or −30 dBm, may be offered where the available hardware power and attenuation permit them.

An output level that cannot be maintained across the entire sweep is rejected rather than silently presented as correct.

The initial reference profile was measured using a LiteVNA67, its supplied blue cable and an external spectrum analyser.

Users are encouraged to calibrate their own instruments for the best possible level accuracy.

Software cannot increase the RF power physically available from the instrument.

Operation beyond the specified frequency range

The LiteVNA67's nominal upper frequency limit is approximately 6.3 GHz.

WHY-Spiced permits experimental frequency settings up to 12 GHz, but this does not imply that the instrument meets any RF performance specification at those frequencies.

Experimental fundamental output has been investigated at frequencies approaching 10 GHz on a particular instrument.

Output amplitude, spectral purity, harmonic content and frequency accuracy must be independently verified.

Operation beyond the manufacturer's specified range is entirely experimental.

Firmware availability and safety

WHY-Spiced is not an official LiteVNA firmware release.

Normal VNA measurements do not require it.

Experimental firmware distribution is subject to clarification of the applicable rights and permissions. The existence of WHY-Spiced functionality does not imply that a modified firmware image is included with every WHY VNA release.

Firmware modifications and flashing may cause instrument malfunction and may require recovery procedures.

Returning control to the instrument or stopping a frequency sweep does not necessarily guarantee that RF output has been disabled.

Measurement validation

WHY VNA is developed and evaluated using actual RF measurement equipment.

Independent measurements have included comparisons with laboratory instruments such as:

• Eaton 2075 Noise Figure Analyzer.

• Giga-tronics 8541 RF power measurement equipment.

• Calibrated RF signal generators and spectrum analysers.

• Reference cables, attenuators and calibration standards.

One comparison involved a KU LNA 144A, where independently measured amplifier gain agreed closely around the 144 MHz passband.

Another investigation used a purpose-built Rogers 2×-Thru fixture and a 51-ohm reference resistor.

After suitable fixture de-embedding, the calculated impedance was substantially closer to the expected component value.

Additional LiteVNA67 investigations have examined:

• Sweep-time dependence on IF integration.

• Single-channel versus two-channel measurements.

• Noise floor and averaging.

• Complex amplitude and phase repeatability.

• Frequency-dependent measurement stability.

• RF synthesizer and firmware behaviour.

These investigations help identify both the capabilities and limitations of affordable VNA hardware.

The separate Practical Measurement Validation document provides measurement examples, screenshots and supporting results.

Files, reporting and compatibility

WHY VNA provides extensive tools for managing, comparing and exporting measurements.

Supported output formats, depending on workspace, include:

• Touchstone S1P and S2P.

• CSV measurement data.

• PNG graphs and screenshots.

• PDF and HTML reports.

• Saved calibration profiles and measurement history.

Supported hardware

Primary supported instruments

• LiteVNA64

• LiteVNA67

• Compatible NanoVNA V2 instruments

Experimental compatibility

• NanoVNA-F V2

Not every hardware platform supports every feature.

Native CW signal generation through WHY-Spiced is specifically an experimental LiteVNA67 capability.

WHY VNA is distributed as a standalone Windows application and normally does not require installation.

Developed for radio amateurs – free of charge

WHY VNA is a personal development project, created out of an interest in RF engineering, measurement technology and amateur radio.

A key motivation is to make advanced measurement techniques available to people who may not have access to expensive commercial instruments or software.

Development is supported by practical testing and valuable feedback from radio amateurs and RF enthusiasts in several countries.

Special thanks to the users and contributors who have helped evaluate the software, including Kurt OZ7OU, Joe 4X1RV and Maurizio IZ1MDJ, and to the hardware and firmware developers whose work makes affordable VNA instruments possible.

The software is free for the amateur radio community. The aim is not to compete on price, but to share knowledge, encourage experimentation and help users get more from the instruments they already own.

Safety and measurement integrity

Never exceed the permissible RF power or DC voltage at the VNA ports.

Take particular care when measuring powered amplifiers, transmitters, bias networks and unfamiliar devices.

Use external attenuators, DC blocks and suitable protection where required.

No software can eliminate the physical limitations of a VNA, its RF hardware, calibration standards or measurement fixtures.

Critical measurements should always be verified using suitable reference equipment.

why-vna-2-2-2.zip

The download package includes the Windows application and its documentation, including the illustrated manual and Practical Measurement Validation report. 

 

If you find WHY VNA useful and would like to support continued development, you can use the Donate button below.