WHY VNA 1.8.7

WHY VNA is a Windows application for controlling, displaying and analysing measurements from LiteVNA and compatible instruments using the supported NanoVNA-style serial protocol.

The software has evolved from a basic VNA interface into a comprehensive measurement environment inspired by professional HP and Agilent network analysers.

WHY VNA combines live instrument control, HP-style softkeys, advanced calibration, markers, Smith charts, filter analysis, TDR, full two-port workflows, complex impedance renormalisation, continuous segmented sweeps, repeated-sweep analysis and hardware-free simulations.

The program is distributed as a single standalone Windows EXE file. A traditional installation is normally not required.

Main VNA display

The main graph uses instrument-style softkeys on the right-hand side. These provide direct access to measurement formats, frequency settings, scaling, calibration, markers, Smith charts and advanced analysis tools.

WHY VNA can display and analyse:

• S11 Log Magnitude and return loss
• S11 SWR
• S11 phase
• Resistance and reactance
• S21 Log Magnitude
• S21 phase
• S21 group delay
• Smith charts
• Admittance Smith charts
• Polar S11 plots
• Multiple simultaneous traces
• Linear and logarithmic frequency axes
• Max Hold and Min Hold
• Trace memory
• Complex trace mathematics
• Reference and difference traces

The Smith chart can be displayed separately or as an overlay on the main graph. Active markers are shown on the rectangular graph, full Smith chart and Smith overlay.

Measurement results and analysis summaries can be displayed directly inside the graph area, similar to a professional bench VNA. Pressing the same result-producing softkey again dismisses an unchanged information overlay.

HP-inspired softkeys

The right-hand softkeys change according to the selected function.

The menu system includes:

• MEAS
• FORMAT
• SCALE
• STIMULUS
• AVG
• CAL
• MARKER
• MARKER SEARCH
• DISPLAY
• HP TOOLS
• TRACE MATH
• GROUP DELAY
• SMOOTHING
• LIMIT LINES
• FULL 2-PORT
• FILTER ANALYSIS
• IMPEDANCE / LCR
• RENORMALISATION
• TIME GATE
• SIMULATION
• SAVE / RECALL
• MEASUREMENT INTEGRITY
• LIVE LAB

Professional segmented sweeps

WHY VNA 1.7.0 introduces professional user-defined segmented sweeps.

Each enabled segment can have its own:

• Start frequency
• Stop frequency
• Number of measurement points
• LiteVNA IF/FFT multiplier from 1 to 80
• Host-side complex averaging
• Calculated frequency step

Segments are measured sequentially and merged into one ordered complex S-parameter result. Touching boundary points are combined automatically.

This allows broad, uninteresting regions to be measured quickly while concentrating more points, narrower IF processing and additional averaging around:

• Filter edges
• Narrow passbands
• Deep notches
• Antenna resonances
• Matching-network transitions
• High-Q crystals and resonators
• Other critical frequency regions

Open the segmented-sweep editor through:

DISPLAY → HP TOOLS → SEGMENT SWEEP

The direct tab route is:

Measurement Tools → Segmented Sweep

Single segmented measurement

Press Run segmented sweep to measure every enabled segment once. The completed result is displayed on the main graph and can be used with markers, Smith charts, limits, filter analysis, trace mathematics and export functions.

Continuous segmented measurement

Press Continuous segmented to repeat the complete segment plan continuously while adjusting a filter, antenna, matching network or resonator.

Press STOP on the main graph, or return to the segmented-sweep editor and press Stop, to end the measurement.

Live sweep display

When LIVE TRACE is enabled, measurement data is displayed while it is received from the instrument.

An optional red vertical line shows the current sweep position.

Open this function through:

DISPLAY → LIVE TRACE ON/OFF

The mouse controls can be used during analysis:

• Mouse wheel – zoom the graph
• Right-drag – pan a zoomed graph horizontally
• Right double-click – restore the complete graph view

Zoom and pan are retained between continuous segmented passes when the frequency grid remains unchanged.

Segmented-sweep demonstration

The supplied segment plan uses three frequency regions around a narrow 14.2035 MHz notch.

The centre segment uses:

• More measurement points
• A larger IF/FFT multiplier
• Additional host averaging

The demonstration compares this with an ordinary uniform sweep. The uniform sweep may sample beside the narrow notch, while the segmented result resolves the critical region in much greater detail.

The same hardware-free comparison is available through:

Sessions & Tools → Demo mode → Segmented sweep advantage → Load demo

Segmentation improves frequency allocation and can improve repeatability when narrower IF processing or averaging is selected. It does not increase the analyser’s intrinsic dynamic range or replace correct calibration.

Markers and automatic searches

WHY VNA provides four independent global markers, M1–M4.

Each marker can display its own measurement quantity. For example:

• M1: S11 SWR
• M2: impedance
• M3: S21 LogMag
• M4: group delay

Marker functions include:

• Peak Max
• Peak Min
• Next Peak
• Track Max
• Track Min
• Track Target
• Target Value
• Marker to Center
• Marker to Reference
• Delta M2–M1
• Bandwidth and Q
• Cable length
• Resonance search

Marker labels show frequency and measurement value directly on the graph. Markers are also displayed on the Smith chart and Smith overlay.

Calibration

WHY VNA includes a complete calibration system with ten storage slots.

A computed calibration profile can use:

• OPEN
• SHORT
• LOAD
• ISOLATION
• THROUGH

Both ideal standards and characterised calibration kits are supported.

A characterised calibration kit can include:

• OPEN capacitance
• OPEN electrical delay
• SHORT inductance
• SHORT electrical delay
• LOAD resistance
• LOAD series inductance
• THROUGH electrical delay
• Reference impedance

Calibration-kit definitions can be saved and reused. Computed calibration profiles can also be exported and imported.

Complex calibration terms can be interpolated to another frequency-point grid, provided the requested sweep remains completely inside the stored calibration range.

An independent verification sweep with a fresh 50-ohm load can be used to evaluate calibration quality.

A calibration slot contains a completed calibration profile. It is not necessary to fill every slot before using the program.

Additional profiles are useful for different:

• Frequency ranges
• Point counts
• Cables and adapters
• Fixtures
• Reference planes
• Forward and reverse measurements

If sweep settings differ from temporary standards captured during a preceding calibration, WHY VNA can clear those temporary captures and begin a new calibration. Saved calibration slots are not affected.

Complex impedance renormalisation

WHY VNA can renormalise a calibrated S11 measurement to a complex source or reference impedance.

For example, if an amplifier data sheet specifies an output impedance of:

12 + j13 ohms

the real and imaginary parts can be entered separately.

The renormalised result can be displayed as:

• S11 LogMag and return loss
• S11 SWR
• S11 phase
• Smith chart
• Marker values
• Other display functions derived from S11

A conjugate-Z function reverses the sign of the reactive component. With a source impedance of 12 + j13 ohms, zero power-wave reflection occurs at the conjugate load:

12 − j13 ohms

Renormalisation is a host-side mathematical transformation. It does not change the original 50-ohm calibration, raw complex data, physical impedance, S21 data or saved calibration profiles.

Full two-port measurements

A normal LiteVNA measurement provides S11 and S21 in one direction.

WHY VNA includes a guided two-direction workflow for obtaining:

• S11
• S21
• S12
• S22

The DUT can be reversed manually or measured through a supported and verified external serial relay controller.

The completed measurement can be exported as a full Touchstone S2P file.

Full two-port accuracy depends on repeatable switching, stable cables, correct port direction and suitable forward and reverse calibration profiles.

Filter analysis

Filter-analysis tools support:

• Low-pass filters
• High-pass filters
• Band-pass filters
• Band-stop filters
• Notch filters
• General frequency responses

Depending on the measurement, WHY VNA can calculate:

• Insertion loss
• Centre frequency
• Cutoff frequency
• Bandwidth
• Loaded Q
• Passband ripple
• Stopband rejection
• Return loss
• SWR
• Group delay

Results can be displayed directly on the graph and used together with markers and limit lines.

Limit lines and PASS/FAIL

Upper and lower limits can be created for Trace 1.

Segmented limits can define different requirements over separate frequency ranges. WHY VNA evaluates all enabled limits and displays PASS or FAIL.

Typical applications include:

• Filter verification
• Antenna bandwidth
• Amplifier gain and flatness
• Attenuator verification
• Cable testing
• Production checks
• Comparison with published specifications

Antenna and impedance analysis

For antenna measurements, WHY VNA can locate resonances and display:

• SWR
• Return loss
• Impedance
• Resistance
• Reactance
• Smith chart
• Admittance Smith chart
• Polar S11
• Bandwidth
• Resonant frequency

Matching tools show how the measured impedance relates to the selected real or complex reference impedance.

Components and resonators

Using calibrated S11 data, WHY VNA can calculate or estimate:

• Resistance
• Reactance
• ESR
• Equivalent inductance
• Equivalent capacitance
• Q

Additional tools provide model fitting and analysis for crystals and other resonators.

High-Q measurements normally require a narrow frequency span, many frequency points, stable fixtures and suitable averaging.

TDR, cable length and time gating

Frequency-domain data can be transformed into time and distance domains for cable and discontinuity analysis.

Available functions include:

• Cable length
• Electrical delay
• Adjustable velocity factor
• Reflection location
• Distance-to-fault display
• TDR display
• Selectable FFT windows
• Time gating
• Keeping or suppressing a selected time interval
• Returning transformed data to the frequency domain

Distance accuracy depends on frequency span, point count, calibration plane, connector delay and cable velocity factor.

Port extension and de-embedding

Port extension can compensate for known electrical delay and move the effective measurement reference plane.

WHY VNA also includes fixture de-embedding tools for reducing the influence of:

• Adapters
• Cables
• Connectors
• Input fixtures
• Output fixtures

Fixture data can be loaded from suitable Touchstone files.

Port extension and de-embedding are mathematical transformations and should be used together with correct calibration and a documented physical measurement setup.

Trace memory and mathematics

Complex measurement data can be stored in multiple memory registers.

Available display operations include:

• DATA
• DATA − MEMORY
• DATA / MEMORY
• DATA + MEMORY

Calculations are performed on complex S-parameters before conversion to dB, phase, SWR or impedance.

Trace memory can be used for normalisation, reference measurements, fixture comparisons and before-and-after measurements.

Measurement integrity

WHY VNA includes diagnostic tools for evaluating measurement quality and stability.

These include:

• Estimated noise floor
• Estimated dynamic range
• Frequency-grid deviation
• Discontinuity detection
• Repeatability
• Comparison with a stored reference
• Calibration status
• Calibration verification
• Measurement-chain information

These results are engineering aids and are not an accredited measurement-uncertainty statement.

Critical measurements should still be verified with suitable standards, known devices and an appropriate uncertainty budget.

Live Measurement Lab

Live Measurement Lab is a coordinated workspace for repeated measurements, antenna adjustment and long-term stability analysis.

It can receive data from:

• Live VNA sweeps
• Imported Touchstone files
• Saved WHY VNA sessions
• Built-in simulations

Sweep History

Sweep History can retain between 2 and 200 measurements.

Older traces are displayed more faintly while the newest trace is brightest. This makes resonance movement, temperature drift, cable movement, connector instability and filter adjustment easier to observe.

The complete retained history can be exported to CSV.

Waterfall display

The waterfall converts every retained sweep into a colour-coded row:

• Horizontal axis – frequency
• Vertical direction – sweep order or time
• Oldest measurement – top
• Newest measurement – bottom
• Colour – selected measurement value

Waterfall is particularly useful for:

• Antenna adjustment
• Crystal drift
• Narrow filters
• Intermittent connectors
• Temperature testing
• Long-term stability measurements

Antenna Tune

Antenna Tune provides a large display of:

• Best SWR
• Resonant frequency
• Physical impedance
• Complete SWR curve

It includes Single Sweep, Continuous Sweep, Stop, Marker to Best SWR and optional audio tuning.

Additional Live Lab displays

Live Measurement Lab also provides:

• Admittance Smith display
• Polar S11 display
• Measurement templates
• Calibration and stability history
• CSV export of repeated measurements

Hardware-free simulations

WHY VNA can be used without connected hardware through fourteen simulated devices under test:

• HF antenna resonance
• Dual-band antenna
• Band-pass filter
• Low-pass filter
• High-pass filter
• Deep notch filter
• Crystal resonator
• 20 dB attenuator
• Wideband amplifier
• 50-ohm verification load
• Open coaxial cable
• Cable discontinuity
• Loose connector or noisy measurement
• Segmented sweep advantage

Simulations are intended for training, demonstrations, regression testing, learning marker operation, testing reports and exports, offline analysis and learning Live Measurement Lab.

Simulated data is deterministic training data and is not a physical measurement.

Projects, sessions and export

A complete measurement can be stored as a WHY VNA project or session.

Supported data and report formats include:

• Touchstone S1P
• Touchstone S2P
• Touchstone 2.0
• CSV
• PNG
• PDF
• HTML reports
• Instrument state files
• Complete WHY VNA measurement projects
• Calibration profiles
• Calibration-kit definitions
• Sweep-history CSV
• Quality-history CSV

Imported Touchstone data can be analysed without connected hardware.

Firmware and device tools

WHY VNA includes separate tools for:

• LiteVNA screen capture
• Live screen display
• PNG export
• LiteVNA firmware files
• USB DFU
• Device diagnostics

Firmware operations should only be performed with a verified firmware image intended for the exact hardware model.

Installation

WHY VNA is supplied as a single standalone Windows x64 EXE file. A traditional installation is normally not required.

To begin:

1. Copy the EXE file to a normal folder.
2. Connect the LiteVNA by USB.
3. Start WHY VNA.
4. Press Refresh.
5. Select the correct COM port.
6. Select the required baud rate, normally 115200.
7. Press Connect.
8. Confirm that the instrument is identified.
9. Configure the sweep.
10. Perform or select a suitable calibration before measuring.

Some security systems may warn about an unsigned or newly downloaded executable. The file should only be obtained from the official WHY VNA distribution source.

Documentation

WHY VNA includes a comprehensive HP-inspired operating and measurement manual in both PDF and editable Microsoft Word formats.

The version 1.7.0 manual contains 168 illustrated pages covering:

• Getting started
• Connection and sweep configuration
• Every softkey and menu
• All supported calibration procedures
• Calibration slots
• Characterised calibration kits
• Markers and Smith charts
• Complex impedance renormalisation
• Filter and antenna measurements
• Full two-port measurements
• TDR and cable-fault analysis
• Port extension and de-embedding
• Limit lines and PASS/FAIL
• Hardware-free simulations
• Live Measurement Lab
• Sweep History and Waterfall
• Continuous segmented sweeps
• Live sweep display
• Projects and data export
• Troubleshooting
• Measurement integrity

Important measurement precautions

Never exceed the permitted DC voltage or RF power at the instrument ports.

Use appropriate protection when the DUT can supply energy, including DC blocks, attenuators, limiters and suitable terminations.

Recalibrate after changing cables, adapters, connectors, fixtures, port direction, reference plane or relevant sweep settings.

For critical measurements:

• Verify the calibration with independent known standards
• Repeat the measurement
• Check cable and connector stability
• Record the complete setup
• Compare results with suitable reference equipment
• Use an appropriate measurement-uncertainty budget

WHY VNA provides extensive engineering and diagnostic tools, but the quality of every result ultimately depends on the instrument, calibration standards, fixture quality, physical setup and measurement procedure.

Download WHY VNA 1.8.7