The mini-whip is meant to be placed outdoors, away from the noise inside a room. I think your tests are being limited by this shortcoming. When you place it outdoors you'll be pleasantly surprised. I'm in the middle of trying to make the same choices with a mini-whip that i built a couple of days ago, so thank you for the video.
Yes, there will be more tests once I can afford some coax and put it outside. There certainly was a point at the higher frequencies where the longer extension brought up the noise floor without bringing up signals though.
I bought one of these recently, tried it and then filed it away under 'R' (for Rubbish). BUT, after watching your video I did some more research, tried it again and now keep it handy for low frequency listening. The key (to my mind anyway) is to think of the 'antenna' as a system consisting of two sensors, one at the top of the mast (the silver pad) and one at ground. In other words, the difference in the electric fields between the top and bottom of the mast is what we are receiving. So, I mounted the sensor on a fiberglass pole (6m), connected a coax to the sensor and then cut a 'band' out of the coax at the base of the mast so that I could earth the coax shielding at the mast base (to a grounding copper rod). Now works fine at low freq and is excellent at rejecting noise. (I noted that the shield of the coax is connected to the sensor's PCB through the SMA, and my next test is to disconnect the coax shield from the coax plug at the top of the mast so that it only has the ground connection at the base of the mast.)
I believe the mini whip depends on the mounting structure/coax to work properly, imagine how it would perform at the top of a quarterwave of a pole ground at the bottom.
I see this video was done 5 years ago, and I'm sure a lot of hams have learned a lot since then about antennas like the Mini-Whip that are designed to reduce noise, but I'll summarize it here for those who have yet to learn about them. As an experienced longwave experimenter I can say without a doubt that the whole purpose of the Mini Whip is NOT to increase sensitivity to signals, but to decrease noise in noisy environments. In a noise-free environment it serves no purpose, as it is not a sensitive antenna. The idea behind it is to have an antenna that reduces noise MORE than it reduces signal. In any given location the existing noise level will determine whether the Mini Whip as configured is advantageous or not. In low noise environments you might as well just hook a longwire to it and use it as a simple pre-amp. But in a high noise environment you will be able to hear more with it than with a larger, more sensitive antenna that will simply fill your radio with noise. Further, the optimal placement of antennas like the Mini Whip is critical. They need to be mounted in the quietest spot you can manage, and they need to have their ground directly below the whip, with no other devices grounded at that point, because combining grounds just adds noise to the system. The Mini Whip (and similar antennas,) is a special-purpose antenna with special installation requirements mandatory in order to get it to do what it was intended to do, reduce noise. Anyone simply sticking one up in the air and plugging it into a radio is defeating its purpose and can expect poor performance.
You've saved time. I was going to do the experiment. I've been using my mini-whip as noise antenna for my noise phaser, but the result wasn't good at all. It might be good now with the extension. TKS 73
The mini whip antenna is an electric field probe. By adding extra metal the capacitance increases so it picks up more of the electric field. There is another way to use the mini whip, as I do myself. I stretched a wire, half a wavelength long at 20m, along the attic. This resonating wire has a higher electric field at the ends and this gets picked up by the mini whip which I placed an inch or two away from the end of this wire. There is no electrical connection to the mini whip, that would be way to strong and overload the amp circuit. OK, it only works as a mono band but it's fun as an experiment anyway. Looking forward to more of your findings with this fun little antenna.
Hey Robert, I was actually thinking about something like that myself earlier. I just moved the miniwhip outside to an enclosure where I was feeding my second HF end fed. The wire is still there, and I was thinking about bringing it over next to the enclosure for capacitive coupling. Might try that this week after I've got a feel for the whip at it's present location. Thanks for watching!
Hi Kevin, the wire antenna has to be shorted at the feedpoint for the best result. When left open, the antenna is just two pieces of shorter wire with a different resonance. Only when shorted will it be one piece and resonate at the proper frequency. You could also try your magnetic loop as a resonator close to the mini whip. Don't transmit near the whip though... All these signal strength enhancing tricks are fun to experiment with but take away from the original idea behind the mini whip which is not necessarily to get the highest signal strength. As long as the atmospheric noise picked up is higher than the receiver's own noise, it is OK to have a weaker signal from the mini whip. More signal doesn't improve the SNR but does cause more intermodulation by AM broadcast stations in the whip's amp circuit. In your video you talk about gain which may increase at a higher supply voltage. The circuit has no gain, it is a voltage follower only. Increasing the supply voltage will only improve the large signal handling but not the level of the output signal.
Thanks for the opening exposing another ghost signal on my SDR PLAY. SDR has been a eye ooener exposing avenues of sig interupters to a very old short wave listener . As if a lightning damaged inverter heatpump was not enough, add the leaky ethernet!
Have you tried placing the mini-whip close to a coupling loop, or maybe better a mag loop? That would be interesting to see if reception becomes greater, as the loops are not attached to the mini-whip directly.
You would almost expect a greater advantage at higher frequencies, just for the fact that a given whip length will be a more appreciable fraction of a wavelength at higher frequencies. Also, Kevin, are you using AGC? It seemed like when you shortened the added whip, the desirable signals seemed to drop and then rise again somewhat.
Kevin, regarding the Ethernet Interference, it's very cost effective to use single mode fiber these days. I have an Enterprise grade switch in my basement and run only short copper runs from it. Anything over 50 feet has been moved to fiber. I use the NetGear 110GS at the end of the run. I did this because of my radio interfering with the network and causing it to kill the IPTV stuff in the living room.
just thinking that with the telecopic whip added it's a bit like a random wire antenna .Would'nt a tuned length improve the signals on a perticular band ?
it seems that each time u move your body or leave the chair the noise gets lower , and when u sit back on that chair it goes up again , it might be a problem with grounding , or its just the parasitic capacitance of your body , or even your body acting like an antenna
You might have been seeing the AGC in the software reacting to the change just made at the whip. There was a couple of seconds after I made a change that the AGC took to settle.
Cubic is quite a lousy tool for this kind of tests as it creates it's own "ghost" signals and does not provide any meaningful measurements. Try Linrad (a pain to learn and use but a proper tool) and measure SNR while generating a low level signal with at signal generator of some sort, a cheap ad9850 module from ebay would suffice.
Yes and No. Cubic does create ghosts, at certain zoom levels only. It's an easy bug to work around once you have a feel for it. The author is aware and hopefully it will be fixed with the next release. GQRX, once you get it working with the SDRPlay, is also viable and more consistent. Linrad is precise, but as you say, tough to learn, and kind of a pain to work with. ;-)
Adding a wire on to a Mini Ship surely turns it into an amplified random wire? So why bother with the mini whip? My testing of a real, not Chinese clone, mini whip and results were not good. Sticking to my random wires.
See University of Twente's impressive implementation of wideband SDR fed by Miniwhip on top of the Engineering school building. This installation has been very well sorted out websdr.ewi.utwente.nl:8901/ Important Miniwhip as high as practical on metal pole with no overlap past amplifier and well below plate. It is also worth thinking of Miniwhip as a photon harvester, which it is!!
Sorry, but these results are not convincing. It would have been better to use steady beacons or AM stations as signal sources so any snr changes could be properly evaluated. Also your "reference electrode" for this electric field detector is a bit of coax connected to a box of RF noise. No wonder it picks up Ethernet. It would be interesting to see how it performs at the top of an earthed metal pole as per the original design.
The mini-whip is meant to be placed outdoors, away from the noise inside a room. I think your tests are being limited by this shortcoming. When you place it outdoors you'll be pleasantly surprised.
I'm in the middle of trying to make the same choices with a mini-whip that i built a couple of days ago, so thank you for the video.
Yes, there will be more tests once I can afford some coax and put it outside. There certainly was a point at the higher frequencies where the longer extension brought up the noise floor without bringing up signals though.
I bought one of these recently, tried it and then filed it away under 'R' (for Rubbish). BUT, after watching your video I did some more research, tried it again and now keep it handy for low frequency listening. The key (to my mind anyway) is to think of the 'antenna' as a system consisting of two sensors, one at the top of the mast (the silver pad) and one at ground. In other words, the difference in the electric fields between the top and bottom of the mast is what we are receiving. So, I mounted the sensor on a fiberglass pole (6m), connected a coax to the sensor and then cut a 'band' out of the coax at the base of the mast so that I could earth the coax shielding at the mast base (to a grounding copper rod). Now works fine at low freq and is excellent at rejecting noise. (I noted that the shield of the coax is connected to the sensor's PCB through the SMA, and my next test is to disconnect the coax shield from the coax plug at the top of the mast so that it only has the ground connection at the base of the mast.)
I believe the mini whip depends on the mounting structure/coax to work properly, imagine how it would perform at the top of a quarterwave of a pole ground at the bottom.
I see this video was done 5 years ago, and I'm sure a lot of hams have learned a lot since then about antennas like the Mini-Whip that are designed to reduce noise, but I'll summarize it here for those who have yet to learn about them.
As an experienced longwave experimenter I can say without a doubt that the whole purpose of the Mini Whip is NOT to increase sensitivity to signals, but to decrease noise in noisy environments. In a noise-free environment it serves no purpose, as it is not a sensitive antenna. The idea behind it is to have an antenna that reduces noise MORE than it reduces signal. In any given location the existing noise level will determine whether the Mini Whip as configured is advantageous or not. In low noise environments you might as well just hook a longwire to it and use it as a simple pre-amp. But in a high noise environment you will be able to hear more with it than with a larger, more sensitive antenna that will simply fill your radio with noise. Further, the optimal placement of antennas like the Mini Whip is critical. They need to be mounted in the quietest spot you can manage, and they need to have their ground directly below the whip, with no other devices grounded at that point, because combining grounds just adds noise to the system. The Mini Whip (and similar antennas,) is a special-purpose antenna with special installation requirements mandatory in order to get it to do what it was intended to do, reduce noise. Anyone simply sticking one up in the air and plugging it into a radio is defeating its purpose and can expect poor performance.
You've saved time. I was going to do the experiment. I've been using my mini-whip as noise antenna for my noise phaser, but the result wasn't good at all. It might be good now with the extension. TKS 73
Thanks for this video. Nice test rig.
The mini whip antenna is an electric field probe. By adding extra metal the capacitance increases so it picks up more of the electric field. There is another way to use the mini whip, as I do myself. I stretched a wire, half a wavelength long at 20m, along the attic. This resonating wire has a higher electric field at the ends and this gets picked up by the mini whip which I placed an inch or two away from the end of this wire. There is no electrical connection to the mini whip, that would be way to strong and overload the amp circuit. OK, it only works as a mono band but it's fun as an experiment anyway.
Looking forward to more of your findings with this fun little antenna.
Hey Robert, I was actually thinking about something like that myself earlier. I just moved the miniwhip outside to an enclosure where I was feeding my second HF end fed. The wire is still there, and I was thinking about bringing it over next to the enclosure for capacitive coupling. Might try that this week after I've got a feel for the whip at it's present location.
Thanks for watching!
Hi Kevin, the wire antenna has to be shorted at the feedpoint for the best result. When left open, the antenna is just two pieces of shorter wire with a different resonance. Only when shorted will it be one piece and resonate at the proper frequency. You could also try your magnetic loop as a resonator close to the mini whip. Don't transmit near the whip though...
All these signal strength enhancing tricks are fun to experiment with but take away from the original idea behind the mini whip which is not necessarily to get the highest signal strength. As long as the atmospheric noise picked up is higher than the receiver's own noise, it is OK to have a weaker signal from the mini whip. More signal doesn't improve the SNR but does cause more intermodulation by AM broadcast stations in the whip's amp circuit.
In your video you talk about gain which may increase at a higher supply voltage. The circuit has no gain, it is a voltage follower only. Increasing the supply voltage will only improve the large signal handling but not the level of the output signal.
Greetings from Sweden!
You must put it on a grounded metal rod or it will not work.
Then also add a 10m+ wire
Thanks for the opening exposing another ghost signal on my SDR PLAY. SDR has been a eye ooener exposing avenues of sig interupters to a very old short wave listener . As if a lightning damaged inverter heatpump was not enough, add the leaky ethernet!
Lol at these dudes lively spirited conversation:))) thanks for vid!
Very thanks Kevin... regards from Brazil
I read that mini whips must be installed outdoors high up clear of any obstructions and metals and wires to work properly.
I have mounted mine in a meter long pvc tube on top of my sensor bar of my ship
Have you tried placing the mini-whip close to a coupling loop, or maybe better a mag loop? That would be interesting to see if reception becomes greater, as the loops are not attached to the mini-whip directly.
I believe if you ground the mast (a conductive mast made of metal) would improve sign to noise ratio, thanks for your great video
You would almost expect a greater advantage at higher frequencies, just for the fact that a given whip length will be a more appreciable fraction of a wavelength at higher frequencies. Also, Kevin, are you using AGC? It seemed like when you shortened the added whip, the desirable signals seemed to drop and then rise again somewhat.
Kevin, regarding the Ethernet Interference, it's very cost effective to use single mode fiber these days. I have an Enterprise grade switch in my basement and run only short copper runs from it. Anything over 50 feet has been moved to fiber. I use the NetGear 110GS at the end of the run. I did this because of my radio interfering with the network and causing it to kill the IPTV stuff in the living room.
Hi I enjoy your videos here in the U.K. Keep the great work de mw3gki
When I ordered the mini whip kit from E-Bay, they threw in about 7 inches of household electrical wire to solder on as an option..
Thank you for this.
wrap the mini whip antena in copper tape all around 2 times without making it bigger , just make it ticker ...
just thinking that with the telecopic whip added it's a bit like a random wire antenna .Would'nt a tuned length improve the signals on a perticular band ?
Since it's such a high gain amplifier, longer lengths just cause it to amplify the noise floor.
A much better test would be using WWV at 5,10 and 15. The HHG NDB is at 417.
it seems that each time u move your body or leave the chair the noise gets lower , and when u sit back on that chair it goes up again , it might be a problem with grounding , or its just the parasitic capacitance of your body , or even your body acting like an antenna
You might have been seeing the AGC in the software reacting to the change just made at the whip. There was a couple of seconds after I made a change that the AGC took to settle.
Cubic is quite a lousy tool for this kind of tests as it creates it's own "ghost" signals and does not provide any meaningful measurements. Try Linrad (a pain to learn and use but a proper tool) and measure SNR while generating a low level signal with at signal generator of some sort, a cheap ad9850 module from ebay would suffice.
Yes and No. Cubic does create ghosts, at certain zoom levels only. It's an easy bug to work around once you have a feel for it. The author is aware and hopefully it will be fixed with the next release.
GQRX, once you get it working with the SDRPlay, is also viable and more consistent.
Linrad is precise, but as you say, tough to learn, and kind of a pain to work with. ;-)
Adding a wire on to a Mini Ship surely turns it into an amplified random wire? So why bother with the mini whip? My testing of a real, not Chinese clone, mini whip and results were not good. Sticking to my random wires.
I added a small 2"x1.5" inch copper plate to mine. Works better.
See University of Twente's impressive implementation of wideband SDR fed by Miniwhip on top of the Engineering school building. This installation has been very well sorted out
websdr.ewi.utwente.nl:8901/
Important Miniwhip as high as practical on metal pole with no overlap past amplifier and well below plate. It is also worth thinking of Miniwhip as a photon harvester, which it is!!
Sorry, but these results are not convincing. It would have been better to use steady beacons or AM stations as signal sources so any snr changes could be properly evaluated. Also your "reference electrode" for this electric field detector is a bit of coax connected to a box of RF noise. No wonder it picks up Ethernet. It would be interesting to see how it performs at the top of an earthed metal pole as per the original design.
Mini whip maximum BS ?