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"Hand capacitance"

CT2FZI All Messages By This Member #735 Hello team, While I was measuring an handheld VU antenna, I noticed that the nanovna was suffering of "Hand capacitance" influence. My unit is an original one, shielded. What can I do to improve it? Have you noticed the same? What about calibration, do you think your hand will influence it? Cheers! LL
Peter Gottlieb All Messages By This Member #737 Are you seeing the effects of your hand on the instrument or on the antenna? Remember also that those antennas are dependent on a counterpoise, usually the HT and your body, so you will see significant difference capacitively coupling your hand to the Nano. You even see thus difference on a full size VNA, so the test setup for those small antennas really matters. Peter toggle quoted message Show quoted text On Aug 5, 2019, at 9:54 AM, spaceopqa@... wrote: Hello team, While I was measuring an handheld VU antenna, I noticed that the nanovna was suffering of "Hand capacitance" influence. My unit is an original one, shielded. What can I do to improve it? Have you noticed the same? What about calibration, do you think your hand will influence it? Cheers! LL
CT2FZI All Messages By This Member #739 Hello Peter, On the device itself. So I will elaborate a little more, as I would like to use one nanovna at the field, as a simple SWR measurement tool, and of course operate it handheld. Maybe it will not occur in a proper HF antenna? Would you isolate the S21 port, or simply the "open" calibration tool will suffice?
Peter Gottlieb All Messages By This Member #740 It should be much better in the field on a proper HF antenna, both because of the counterpoise and also the lower frequencies involved. Well at least your HF antenna should have a proper counterpoise, or your HF transmitter will be “hot” when you transmit. Peter toggle quoted message Show quoted text On Aug 5, 2019, at 10:15 AM, spaceopqa@... wrote: Hello Peter, On the device itself. So I will elaborate a little more, as I would like to use one nanovna at the field, as a simple SWR measurement tool, and of course operate it handheld. Maybe it will not occur in a proper HF antenna? Would you isolate the S21 port, or simply the "open" calibration tool will suffice?
Mike Brown All Messages By This Member #744 I saw similar effects myself when testing the antenna from a handheld transceiver. As Peter says it is to be expected as, in its intended use, the human operator together with the conductive part of the rig form the ground plane that is required by that type of simple vertical antenna. No hand effects have been noticeable when I have tested HF, VHF & UHF verticals (all with adequate radial systems) or with VHF/UHF yagis. There seems to be no need to do anything with the s21 port but it would probably be good practice to put a 50ohm load on it. Regards toggle quoted message Show quoted text On Mon, 5 Aug 2019, 15:15 , <spaceopqa@...> wrote: Hello Peter, On the device itself. So I will elaborate a little more, as I would like to use one nanovna at the field, as a simple SWR measurement tool, and of course operate it handheld. Maybe it will not occur in a proper HF antenna? Would you isolate the S21 port, or simply the "open" calibration tool will suffice?
Frank S All Messages By This Member #745 You can try a short coax loaded with low freq ferrites that fit tight on the coax. It helps (somewhat). Cal at the end of the coax toggle quoted message Show quoted text On 8/5/2019 12:13 PM, Mike Brown wrote: I saw similar effects myself when testing the antenna from a handheld transceiver. As Peter says it is to be expected as, in its intended use, the human operator together with the conductive part of the rig form the ground plane that is required by that type of simple vertical antenna. No hand effects have been noticeable when I have tested HF, VHF & UHF verticals (all with adequate radial systems) or with VHF/UHF yagis. There seems to be no need to do anything with the s21 port but it would probably be good practice to put a 50ohm load on it. Regards On Mon, 5 Aug 2019, 15:15 , <spaceopqa@...> wrote: Hello Peter, On the device itself. So I will elaborate a little more, as I would like to use one nanovna at the field, as a simple SWR measurement tool, and of course operate it handheld. Maybe it will not occur in a proper HF antenna? Would you isolate the S21 port, or simply the "open" calibration tool will suffice?
Stuart Landau All Messages By This Member #747 An antenna without a counterpoise (ground or ground-plane) is just a piece of wire. If you are testing a "rubber duckie" I would recommend mounting it onto a piece of metal; even a piece of aluminum foil would give a truer reading. A whip antenna mounted on a hand-held radio is a poor compromise, but at least the radio and your hand acts as a sort of ground.When I worked for Kenwood USA and Standard Communications we did some antenna testing of this sort. Stuart K6YAZLos Angeles, USA toggle quoted message Show quoted text -----Original Message----- From: Frank S <ka2fwc@...> To: nanovna-users <[email protected]> Sent: Mon, Aug 5, 2019 9:33 am Subject: Re: [nanovna-users] "Hand capacitance" You can try a short coax loaded with low freq ferrites that fit tight on the coax. It helps (somewhat). Cal at the end of the coax On 8/5/2019 12:13 PM, Mike Brown wrote: I saw similar effects myself when testing the antenna from a handheld transceiver. As Peter says it is to be expected as, in its intended use, the human operator together with the conductive part of the rig form the ground plane that is required by that type of simple vertical antenna. No hand effects have been noticeable when I have tested HF, VHF & UHF verticals (all with adequate radial systems) or with VHF/UHF yagis. There seems to be no need to do anything with the s21 port but it would probably be good practice to put a 50ohm load on it. Regards On Mon, 5 Aug 2019, 15:15 , <spaceopqa@...> wrote: Hello Peter, On the device itself. So I will elaborate a little more, as I would like to use one nanovna at the field, as a simple SWR measurement tool, and of course operate it handheld. Maybe it will not occur in a proper HF antenna? Would you isolate the S21 port, or simply the "open" calibration tool will suffice?

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