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Antenna analyser

Posted: Thu Aug 07, 2014 11:06 am
by VK6MB
I thought I had seen where some one had used their RP as an Antenna analyser.
Am I imaging things or am I looking in the wrong place?
I have been looking at Fox Delta AAZ-0713A Antenna Analyzer, but if I can do it all with the RP would be better.

Regards Mike

Re: Antenna analyser

Posted: Mon Aug 18, 2014 1:42 pm
by Crt Valentincic
The idea sure is visible and I think there are already some partial solutions like Gain/Phase/Impedance Analyser, Frequency response analyzer application. Could you suggest most useful features of such tool?

Re: Antenna analyser

Posted: Mon Aug 18, 2014 1:56 pm
by VK6MB
Hi Črt,
I had a look at that analyser and can see the way it measures a two port device like a filter, but would like to sweep/test a single port device like an antenna, from say 1MHz to 30MHz, to find where it is resonating and suitable for the different amateur radio bands.
I don't know how to set it up for this purpose.
Regards
Mike

Re: Antenna analyser

Posted: Fri Feb 06, 2015 9:13 am
by piccolo
To use the RP as an antenna analyzer you'd probably need a hardware adapter to bridge the DAC and ADC to the antenna port. An antenna analyzer application could be realized as a swept dip meter[1]; the DAC would sweep across the desired frequency range, while the ADC would measure the returned energy. The application would plot frequency vs. returned energy; wherever the antenna is resonant this graph will show a dip.

This kind of tool is invaluable in antenna construction; adding such a capability to the RP would double its worth in the lap of a radio amateur.

[1] http://en.wikipedia.org/wiki/Dip_meter

Re: Antenna analyser

Posted: Thu Feb 19, 2015 6:16 am
by areeba
ok thanks piccolo for given Wikipedia link :D :D :D

Re: Antenna analyser

Posted: Tue Feb 24, 2015 2:30 pm
by fastjack
Hi,
I think the idea of an antenna analyser is very cool, but the potential is much bigger!
The Rep Pitaya has al the means to be a vector network analyser. The difference between antenna analyser and vector network analyser is that the latter can also measure the phase.
The LCR meter (web interface) already goes a long way to be such a tool. However it lacks calibration.
Calibration is absolutely necessary for measuring RF signals. This calibration should include 3 ways: open, short and a known termination, say 50 ohms resistor. Once this is accomplished you will be able to do very accurate measurements at the terminal of calibration.

more info:
http://en.wikipedia.org/wiki/Network_an ... ctrical%29

I am convinced the hardware is already here to unleash a great tool!

Keep up the good work!
Fastjack

Re: Antenna analyser

Posted: Sat Apr 11, 2015 7:23 pm
by piccolo
fastjack wrote: The LCR meter (web interface) already goes a long way to be such a tool. However it lacks calibration.
Calibration is absolutely necessary for measuring RF signals. This calibration should include 3 ways: open, short and a known termination, say 50 ohms resistor. Once this is accomplished you will be able to do very accurate measurements at the terminal of calibration.
For those of us who have open/short/50-ohm calibration tools lying around already, what kind of modifications need to be made to the LCR Meter app to get this working?

Re: Antenna analyser

Posted: Wed Apr 29, 2015 6:46 am
by DeGaCo
You need a directional coupler to get the reflected power than you can measure the reflection coefficent and calculate the VSWR. In this frequency range up to 30MHz I am not sure that a calibration is necessary. It is dependet on the quality of the coupler.
The problem with coupler is the limited bandwith. A transformator will cover the range 1MHz - 30MHz.
http://en.wikipedia.org/wiki/Power_divi ... l_couplers

For a vector network analyser look at
http://en.wikipedia.org/wiki/Network_an ... ctrical%29
You need two switch, two power splitter and two directional coupler. Because the RP has only two inputs the second switch will connect successive the signals to the input ports. To compensate the influence of the components a calibration will be necessary.
http://cp.literature.agilent.com/litweb ... -7709E.pdf

Re: Antenna analyser

Posted: Thu Mar 31, 2016 11:46 pm
by Drachenfrucht
Hi all,

is there meanwhile any news on that? I am also interested in a solution with the RedPitaya to "measure" various antennas. I'd like to find out the "resonance" of an antenna, it should display the exact frequencies the meausured antenna is resonant on. It would be awesome to have such a tool. And it would also be awesome to have the VSWR showed for a range of frequency. Is that somehow possible meanwhile?

Looking forward to your comments and help.

Re: Antenna analyser

Posted: Fri Apr 01, 2016 12:14 am
by pavel
I could suggest to try the Ham VNA program with the SDR/HPSDR application.