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$10,756
pledged of $10,731 goal
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All or nothing. This project will only be funded if it reaches its goal by .

By Cary Wang
$10,756
pledged of $10,731 goal
backers

All or nothing. This project will only be funded if it reaches its goal by .

What is a prototype?

A prototype is a preliminary model of something. Projects that offer physical products need to show backers documentation of a working prototype. This gallery features photos, videos, and other visual documentation that will give backers a sense of what’s been accomplished so far and what’s left to do. Though the development process can vary for each project, these are the stages we typically see:

Proof of Concept

Explorations that test ideas and functionality.

Functional Prototype

Demonstrates the functionality of the final product, but looks different.

Appearance Prototype

Looks like the final product, but is not functional.

Design Prototype

Appearance and function match the final product, but is made with different manufacturing methods.

Production Prototype

Appearance, function, and manufacturing methods match the final product.

A26bfda77926149f86f5dc3bf6b8147b original

Prototype Gallery

These photos and videos provide a detailed look at this project’s development.

About

The xaVNA is a two port VNA with a typical frequency range of 137MHz to 3.5GHz, and a guaranteed frequency range of 140MHz to 2.5GHz. It plugs directly into USB and requires no additional power supply. All measurements are done using an intuitive and easy to use UI on a computer.

It is both open source hardware and open source software, with a GitHub repository containing all schematics, PCB layouts, FPGA VHDL, and software that will be kept updated during development:

https://github.com/xaxaxa/vna

Stretch goal: C$25,000

We will introduce a 10MHz to 2.5GHz version if budget permits.

What can you do with the xaVNA?

A VNA (Vector Network Analyzer) allows you to measure the impedance of an arbitrary device (such as an antenna) across a wide range of frequencies, as well as the transmission coefficient (gain/loss and phase) of a two port device (such as an amplifier, filter, or isolator).

It can do everything an antenna analyzer can do, but 10x better: it gives you phase information as well, and lets you see the exact complex impedance of an antenna, allowing you to easily design matching networks without tedious trial and error tuning.

What makes the xaVNA superior?

  • Less trace noise than other low cost VNAs on the market (see graphs below)
  • No warm-up needed: achieves spot-on measurements within 1 minute of power up
  • Entirely powered from USB; no power adapter needed
  • Open source hardware & software
  • Lower cost

How accurate is it? What are the specs?

  • Frequency range (guaranteed): 140MHz to 2.5GHz
  • Frequency range (typical): 137MHz to 3.5GHz (achieved in iteration 1 prototype)
  • Signal level: -20dBm to 10dBm (achieved in iteration 1 prototype)
  • S11 trace noise: <<0.1dB (achieved in iteration 1 prototype)
  • S11 dynamic range: >50dB (achieved in iteration 1 prototype)
  • S21 dynamic range: target >=70dB (achieved 50dB in iteration 1 prototype)
  • Dimensions of the VNA board: 10cm x 10cm
  • Weight: <200g
  • Interface: Micro USB
  • RF ports: SMA Female
  • Current draw: ~500mA @ 5V
  • Windows, Linux, and Mac OS will be supported

Accuracy comparison (measured vs simulated):

 

 

 

Comparison to other low cost VNAs on the market:

See last page of http://www.gsm-modem.de/M2M/wp-content/uploads/2014/04/IoT-M2M-Cookbook-Harald_excerpt.pdf

What is the current status of the project?

We have a fully functional prototype on a 2-layer PCB, as shown in the demo. For iteration 2 all the wiring (including the coaxial cables) will be eliminated and everything will be on one board, to prepare for mass production. The iteration 2 PCB has already been designed and is now undergoing DFM verification.

What will the final product look like?

The T/R version next prototype and final product will be a single 10cm x 10cm 4-layer PCB; Here is a top view rendering of the current design:

The full two-port version will be a similar but slightly larger PCB (estimated 10cm x 15cm).

If time and budget permits, we may include an acrylic case.

Software and interfacing

Software will be provided for Windows, Linux, and Mac OS. An API (in C/C++) will be provided to control and read data from the VNA from your application. All code will be licensed under the GPLv2 and will be available on GitHub.

A screenshot of the software in development:

(Measuring a 900MHz power amplifier)

Features:

  • SOL calibration
  • Smith chart
  • Impedance, admittance, and series/parallel equivalent value display
  • S parameter export (s1p and s2p)
  • S11, S21, S22, S12 magnitude/phase plots
  • Distance to fault graph
  • Persistence plot

Calibration kit

The provided calibration kit will consist of 3 SMA female connectors (for short/open/load), one SMA-f to SMA-f adapter (for through), and 2x 100ohm precision resistors. The references need to be soldered like so:

If you would like the calibration references pre-soldered (at no charge), leave a remark with your pledge. 

What is the difference between the T/R version and the full two port version?

A T/R VNA allows you to measure S11 and S21, that is reflection coefficient on port 1 and transmission from port 1 to 2. To measure S22 and S21 you will need to physically reverse the DUT. The full two port version has a directional coupler and signal source on both ports, allowing you to measure S11, S21, S12, and S22 as well as calibrate with an unknown length through reference.

Risks and challenges

The T/R version iteration 1 prototype is fully working and achieves almost all of the target specs, and iteration 2 DFM (design for manufacturability) is close to completion. A quotation has been received for all parts and PCB assembly. This is our first time designing something for manufacture in volume, but we are confident in being able to deliver given the above.

The full two port version will require more R&D.

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    Pledge CA$ 259 or more About $207

    xaVNA T/R + cal kit - Early Bird

    (~$207 USD) Get one xaVNA unit. Measures S11 and S21. Includes VNA board (fully assembled), and calibration kit (requires soldering). Micro USB cable and SMA cables NOT included.

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    Pledge CA$ 279 or more About $223

    xaVNA T/R

    (~$223 USD) Get one xaVNA unit. Measures S11 and S21. Includes VNA board (fully assembled). Micro USB cable and SMA cables NOT included.

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    Pledge CA$ 299 or more About $239

    xaVNA T/R + cal kit

    (~$239 USD) Get one xaVNA unit. Measures S11 and S21. Includes VNA board (fully assembled) and calibration kit (requires soldering). Micro USB cable and SMA cables NOT included.

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    xaVNA T/R + cal kit x2 - Early Bird

    (~$410 USD) Get two xaVNA units and calibration kits. Measures S11 and S21. Includes VNA board (fully assembled) and calibration kit (requires soldering). Micro USB cable and SMA cables NOT included.

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    Pledge CA$ 649 or more About $519

    xaVNA two-port

    (~$520 USD) Get one xaVNA full two-port unit. Measures S11, S21, S12, S22. Includes VNA board (fully assembled). Micro USB cable and SMA cables NOT included.

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    Pledge CA$ 669 or more About $535

    xaVNA two-port + cal kit

    (~$536 USD) Get one xaVNA full two-port unit. Measures S11, S21, S12, S22. Includes VNA board (fully assembled), and calibration kit (requires soldering). Micro USB cable and SMA cables NOT included.

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    Pledge CA$ 249 or more About $199

    xaVNA T/R + cal kit - Super Early Bird

    (~$199 USD) Get one of the first 10 units of the xaVNA. Measures S11 and S21. Includes VNA board (fully assembled), and calibration kit (requires soldering). Micro USB cable and SMA cables NOT included.

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