Help with new VNA design.
时间：04-04
整理：3721RD
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Hello,
In the past I developed some RF products but it was very hard develop a good RF product. The antenna didn't work good anymore when I put the product (with PCB antenna) in the housing. I used the RF explorer generator and spectrum analyzer to optimize antenna's (as a SNA). Now I want to develop a cheap and good VNA myself for the (open source) community.
This will be the VNA in short:
*Function generator (ADF4351 goes up to 4400MHz, the only disadvantage is that this component does not generate a signal below 35MHz). What requirements are needed for the frequency generator? There are only 3 output power options? Should I put an amplifier on the output? Is it a disadvantages that you only have frequencies above the 35MHz? Do you have an alternative?
*power splitters, directional coupler and AD8302 (AD8302 'only' goes up to 2.7GHz)
*ADC to measure the output signals of the AD8302 (how many bits are needed? What are the most important things of this ADC (resolution? stability reference voltage? conversion time is not so important, since the measurement only takes longer?)? Minimum of how many bits?
*the MCU will set the frequency, handle the phase/amplitude difference from the AD8302 and send the result to the PC by USB. It's also possible to connect a LCD, but I think everything will be handled on the PC. My first setup will be a VNA that needs a PC to handle the result.
*The most important thing is the stability. I think this can be solved by these things: very stable reference frequency for ADF4351, very stable reference voltage for ADC).
Is it necessary to measure the output frequency again (with a splitter/prescaler)? If the ADF4351 has a very stable reference frequency, I can count on the correct output frequency, can't I?
Any help is appreciated. The goal is to make a simple and cheap VNA. The most important thing is the stability of the VNA (VNWA is stable, MiniVNA is less stable). I want use stable components where needed (stable reference frequency and reference voltage).
I will start with all the parts separately. Frequency generator with STM32(USB VCP), splitters, directional coupler, STM32/ADC/AD8302 (USB VCP), etc.
Hopefully you can help me with this project. Any help is appreciated.
Kind regards,
Mark
In the past I developed some RF products but it was very hard develop a good RF product. The antenna didn't work good anymore when I put the product (with PCB antenna) in the housing. I used the RF explorer generator and spectrum analyzer to optimize antenna's (as a SNA). Now I want to develop a cheap and good VNA myself for the (open source) community.
This will be the VNA in short:
*Function generator (ADF4351 goes up to 4400MHz, the only disadvantage is that this component does not generate a signal below 35MHz). What requirements are needed for the frequency generator? There are only 3 output power options? Should I put an amplifier on the output? Is it a disadvantages that you only have frequencies above the 35MHz? Do you have an alternative?
*power splitters, directional coupler and AD8302 (AD8302 'only' goes up to 2.7GHz)
*ADC to measure the output signals of the AD8302 (how many bits are needed? What are the most important things of this ADC (resolution? stability reference voltage? conversion time is not so important, since the measurement only takes longer?)? Minimum of how many bits?
*the MCU will set the frequency, handle the phase/amplitude difference from the AD8302 and send the result to the PC by USB. It's also possible to connect a LCD, but I think everything will be handled on the PC. My first setup will be a VNA that needs a PC to handle the result.
*The most important thing is the stability. I think this can be solved by these things: very stable reference frequency for ADF4351, very stable reference voltage for ADC).
Is it necessary to measure the output frequency again (with a splitter/prescaler)? If the ADF4351 has a very stable reference frequency, I can count on the correct output frequency, can't I?
Any help is appreciated. The goal is to make a simple and cheap VNA. The most important thing is the stability of the VNA (VNWA is stable, MiniVNA is less stable). I want use stable components where needed (stable reference frequency and reference voltage).
I will start with all the parts separately. Frequency generator with STM32(USB VCP), splitters, directional coupler, STM32/ADC/AD8302 (USB VCP), etc.
Hopefully you can help me with this project. Any help is appreciated.
Kind regards,
Mark