Logo VNA-dsp / Antenna Analyzer

VNA-dsp overall

Completed Unit

Project Description

This project is my attempt to build a portable standalone VNA (Vector Network Analyzer). My main focus was to build an instrument that could be used at the antenna feed point to measure impedances. Once the antenna impedance is known, the smith chart can be used to suggest various matching networks. This instrument uses the VNA RF board by Paul N2PK . I received a great deal of information from Greg W8WWV regarding some of the complex math involved dealing with the analyzer computations and calibration. He kindly provided the sources for his gnat and exeter windows programs which I used to develop the vna-dsp software. Greg also supplied blank PCB boards for the VNA and the reflection bridge. I sourced most of the parts through the Analog Devices sample program, Digikey, the National Semicondutor sample program, and the Microchip sample program. My thanks to the hams and companies that made this project possible.
The N2PK board is meant to be used with a computer or laptop as the operator interface. This project uses a very powerful micro controller (the dsPic30f4011) to tie together the 2x24 LCD display, 3 push buttons, a home made rotary encoder for frequency selection, a battery voltage monitor, a serial remote computer interface, a dual regulated 5V supply (one for the rf board and one for the digital processor board) and the VNA board. The whole box is powered by 8 AA Nimh cells.
This project turned out to be a quite an undertaking.

In the process I had to:
Below are some pictures I took as the project progressed...

VNA-dsp power supply board top VNA-dsp power supply board bottom

Power Supply Board (dual 5 volt regulators) Top and Bottom

VNA-dsp cpu board top VNA-dsp cpu board bottom bottom

dsPic 30F4011 CPU Board Top and Bottom (note surface mount resistors and bypass caps)

VNA-dsp front panel/display VNA-dsp encoder made from mouse/pot parts

Front Panel LCD display and Buttons, Encoder (from Mouse Parts)

VNA-dsp power/rf sub assembly VNA-dsp dsp cpu sub assembly

Power/RF Assembly and the dsPIC Assembly on each side of a sub-panel

VNA-dsp return loss bridge

All the pieces mated together showing the Return Loss Bridge PCB

User Interface Description

System Requirements

A lot of this project is mechanical packaging of various components. The Microchip MPLab integrated development environment with the C30 compiler was used running under VMware/WindowsXP on an Ubuntu linux computer. The MPLab project files and all the source code files are available later on this page. The eagle PCB files are supplied below for the power supply and the processor board. I do not have plans to market this project or any of its parts. I am releasing this design and software for anyone to use for non commercial use. I am available as a consultant for commercial applications of this or similar products. My contact information is available on my home page.

Planned improvements

Electrical Drawing(s)

power supply schematic - vna-ps-sch.png(27.7K)
processor board schematic- vna-dsp-sch.png(67.5K)

Source Code

power supply - eagle schematic - vna-powersupply.sch(156.4K)
power supply - eagle board - vna-powersupply.brd(8.8K)
processor - eagle schematic - vna-dspic.sch(131.0K)
processor - eagle board - vna-dspic.brd(19.8K)
VNA-dsp project source code - vna-dsp-19may2006.zip(111K)
VNA-dsp project source code - vna-dsp-30nov2006.zip(114K)
VNA-dsp project source code - vna-dsp-22dec2007.zip(130K) interim release with SWR calc fix
VNA-dsp project source code - vna-dsp-14jan2008.zip(170K) supports bootloader or standalone operation

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