When doing stuff like this try to mount your antenna on a pole or in free space dangling on a fishing line etc. but note it will act differently in each situation. If mono-band you can add a coax transforming loop (balun /tuner / filter) at the feedpoint to minimize any effect of the coax shield acting as part of the antenna which can also help to minimise some unwanted swr results / changes due to coax lengths and some objects in proximity to coax runs. Adding such tuned transformers such as these coax loops or baluns as well as ferrite sleeves at the feedpoint can also change your radiation pattern as well as help to maximise efficiency and reduce unwanted noise both in and out of the system.
This would be a better video if the screen was cleared of the extra traces. This way there is to much clutter. Other wise this is a good lesson. Thank You
Some of these have telescopic radials too as you'll be wanting to change the length of those too. Very nice idea, hopefully making one myself for the summer.
You need to first turn all that display clutter off. Leave the Smith chart and the SWR chart. Next, set the frequency range (Stimulus) that you are going to use. Then, you need to calibrate the unit at the END of the coax you are using. Detach the antenna but not the coax. Run the calibration using the open, short, and load terminations at the END of the coax. Save the calibration. Connect the antenna. NOW you will be seeing what the antenna is really doing.
Hello! It's my question that how we can test an antenna for a bipolar monopulse uwb signal for example if that signal has a 5ns width and 100khz repetition..What is the frequency that I have to use as start and stop on nanovna to measure my antenna parameters?????
All good with swr but what about conductance or capacitance behaviour of this system, (coax cable & antenna)? I mean when i have an antenna with transmission line which give to me a good swr factor and z, (aprox 50Ωμ), but i have a small value of capacitance, (200pF for example), to smith graph. Is this value of capacitance affect the tramsmission signal or not?
In the beginning of the video you said that you want... "to see the performance of the antenna". Thank to a so low SWR, now we know that the losses in that antenna are almost 28%. After the coax losses, only a 72% of the remaining power will be radiated
I like this man! Does it cover all bands including CB band at 26.92mhz to 27.405mhz? Does this mean you could adjust most antennas for best SWR without first installing them?
Nice video & propper tuning the 140 mhz telescoping whip from it's fully collapsed (too short) to 1st Resonant 1/4 wavelength extended length, but you probably blew your 70 cm (440 mhz) Real 1/4 Resonant whip length & really hit it's 3rd harmonic length....At about 20 secs in the video, the fully Collapsed antenna appears to be about 3 X time length of your NanoVNA width of 3.5 inches or bout 10" long....You slowly extended that to about doubled to 20 inches tall, which Is real close to a 1/4 wavelength 144 mhz 2 meter band antenna.....Knowing the 70 cm band (440 mhz) Is exactly 3 X times Shorter than 2 meters, you barely collapsed the whip Nowhere to it's correct 440 mhz height of about 11 inches....Congrats,.....you probably incorrectly Resonated on it's 3rd harmonic, way too long length !! Still a good show on what can go wrong when tuning from a way too long whip length & settling for the 1st "that looks good" NanoVmna display.......
You need to recalibrate when you change the frequencies.
When doing stuff like this try to mount your antenna on a pole or in free space dangling on a fishing line etc. but note it will act differently in each situation. If mono-band you can add a coax transforming loop (balun /tuner / filter) at the feedpoint to minimize any effect of the coax shield acting as part of the antenna which can also help to minimise some unwanted swr results / changes due to coax lengths and some objects in proximity to coax runs. Adding such tuned transformers such as these coax loops or baluns as well as ferrite sleeves at the feedpoint can also change your radiation pattern as well as help to maximise efficiency and reduce unwanted noise both in and out of the system.
This would be a better video if the screen was cleared of the extra traces. This way there is to much clutter.
Other wise this is a good lesson. Thank You
Pretty cool, I think I might need to get one of these to play with my home brew antennas, thanks for the demonstration..
Some of these have telescopic radials too as you'll be wanting to change the length of those too. Very nice idea, hopefully making one myself for the summer.
I think, you must adjust the VNA to the length of the coaxial cable.
It would have been neat to see what would have happened if you could change the radials some leaving the vertical at its last best SWR setting.
why didn"t you shut off the other traces, so the SWR Trace would be easier to see?
You need to first turn all that display clutter off. Leave the Smith chart and the SWR chart. Next, set the frequency range (Stimulus) that you are going to use. Then, you need to calibrate the unit at the END of the coax you are using. Detach the antenna but not the coax. Run the calibration using the open, short, and load terminations at the END of the coax. Save the calibration. Connect the antenna. NOW you will be seeing what the antenna is really doing.
Hello!
It's my question that how we can test an antenna for a bipolar monopulse uwb signal for example if that signal has a 5ns width and 100khz repetition..What is the frequency that I have to use as start and stop on nanovna to measure my antenna parameters?????
All good with swr but what about conductance or capacitance behaviour of this system, (coax cable & antenna)? I mean when i have an antenna with transmission line which give to me a good swr factor and z, (aprox 50Ωμ), but i have a small value of capacitance, (200pF for example), to smith graph. Is this value of capacitance affect the tramsmission signal or not?
Sir if I have copper pipe solid antenna then I have to cut
Please advice
In the beginning of the video you said that you want... "to see the performance of the antenna".
Thank to a so low SWR, now we know that the losses in that antenna are almost 28%.
After the coax losses, only a 72% of the remaining power will be radiated
So, the longer the antenna, the higher the SWR?
I like this man!
Does it cover all bands including CB band at 26.92mhz to 27.405mhz?
Does this mean you could adjust most antennas for best SWR without first installing them?
Yes and yes.
@@doug5uk Mine arrived yesterday. Glad to see it has a USB charger.
I love it but cant analyse anything because the pl 259 adapter didn't ship yet.
Will the SWR stay the same if you move that antenna up on your roof versus in your shack?
No.
Yes if the components are all the same.
@@DogFacePuffa Not necessarily yes, because the environment can change the properties, e.g. any metal structures around.
I dont know if swr measures reaonance, i think logmag is better for that
You are not measuring any performance! You are just measuring SWR in a 50 ohm system
tot nu toe begrijp ik er geen moer van.....................
Nice video & propper tuning the 140 mhz telescoping whip from it's fully collapsed (too short) to 1st Resonant 1/4 wavelength extended length, but you probably blew your 70 cm (440 mhz) Real 1/4 Resonant whip length & really hit it's 3rd harmonic length....At about 20 secs in the video, the fully Collapsed antenna appears to be about 3 X time length of your NanoVNA width of 3.5 inches or bout 10" long....You slowly extended that to about doubled to 20 inches tall, which Is real close to a 1/4 wavelength 144 mhz 2 meter band antenna.....Knowing the 70 cm band (440 mhz) Is exactly 3 X times Shorter than 2 meters, you barely collapsed the whip Nowhere to it's correct 440 mhz height of about 11 inches....Congrats,.....you probably incorrectly Resonated on it's 3rd harmonic, way too long length !! Still a good show on what can go wrong when tuning from a way too long whip length & settling for the 1st "that looks good" NanoVmna display.......