Antenna analyser

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VK6MB
Posts: 4
Joined: Wed Jun 11, 2014 9:21 am

Antenna analyser

Post by VK6MB » Thu Aug 07, 2014 11:06 am

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

Crt Valentincic
Posts: 67
Joined: Wed May 28, 2014 12:15 pm

Re: Antenna analyser

Post by Crt Valentincic » Mon Aug 18, 2014 1:42 pm

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?

VK6MB
Posts: 4
Joined: Wed Jun 11, 2014 9:21 am

Re: Antenna analyser

Post by VK6MB » Mon Aug 18, 2014 1:56 pm

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

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piccolo
Posts: 8
Joined: Fri Feb 06, 2015 8:51 am
Location: USA

Re: Antenna analyser

Post by piccolo » Fri Feb 06, 2015 9:13 am

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

areeba
Posts: 1
Joined: Thu Feb 19, 2015 6:10 am

Re: Antenna analyser

Post by areeba » Thu Feb 19, 2015 6:16 am

ok thanks piccolo for given Wikipedia link :D :D :D

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fastjack
Posts: 8
Joined: Mon Nov 10, 2014 12:01 pm
Location: The Netherlands

Re: Antenna analyser

Post by fastjack » Tue Feb 24, 2015 2:30 pm

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

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piccolo
Posts: 8
Joined: Fri Feb 06, 2015 8:51 am
Location: USA

Re: Antenna analyser

Post by piccolo » Sat Apr 11, 2015 7:23 pm

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?

DeGaCo
Posts: 1
Joined: Wed Apr 29, 2015 6:14 am

Re: Antenna analyser

Post by DeGaCo » Wed Apr 29, 2015 6:46 am

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

Drachenfrucht
Posts: 34
Joined: Fri Mar 18, 2016 12:18 am

Re: Antenna analyser

Post by Drachenfrucht » Thu Mar 31, 2016 11:46 pm

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.

pavel
Posts: 531
Joined: Sat May 23, 2015 5:22 pm

Re: Antenna analyser

Post by pavel » Fri Apr 01, 2016 12:14 am

I could suggest to try the Ham VNA program with the SDR/HPSDR application.

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