Testing HT antennas

Matthew Rapaport Всі повідомлення цього користувача #38082 Simple S11 tests of small HT antennas never yield expected results... When I test my mag mount on my car or J-pole hanging off the roof of a wooden porch (both at the end of hard-wired 10' coax and PL-251 connectors) I get expected values. SWR and resonance points (Smith chart) fall in the 2m & 70cm bands... But... When I try to test my HT antennas either connected to S11 directly or at the end of a short piece of coax (the VNA is properly calibrated under both conditions) lowest SWR and resonance are not in band, but 8-10 mHz outside them. These are good antennas too, Abbree, Flexi-whip, Nagoya, etc. They work fine ON the HTs... I'm thinking the proximity of the VNA itself and lots of other metal (grounded and not) in my test environment are to blame... Any suggestions?
Dragan Milivojevic Всі повідомлення цього користувача #38083 HT antennas are designed to work with your device in your hand ... On Wed, 25 Sept 2024 at 14:25, Matthew Rapaport via groups.io <quineatal@...> wrote: Simple S11 tests of small HT antennas never yield expected results... When I test my mag mount on my car or J-pole hanging off the roof of a wooden porch (both at the end of hard-wired 10' coax and PL-251 connectors) I get expected values. SWR and resonance points (Smith chart) fall in the 2m & 70cm bands... But... When I try to test my HT antennas either connected to S11 directly or at the end of a short piece of coax (the VNA is properly calibrated under both conditions) lowest SWR and resonance are not in band, but 8-10 mHz outside them. These are good antennas too, Abbree, Flexi-whip, Nagoya, etc. They work fine ON the HTs... I'm thinking the proximity of the VNA itself and lots of other metal (grounded and not) in my test environment are to blame... Any suggestions?
Mike N2MS Всі повідомлення цього користувача #38084 I test HT antennas to simulate them in operation. For example, if I hold the HT close to my face to talk into the mic. I replace the HT with the VNA and hold the VNA in my operating position and read the results. Mike N2MS переключити цитоване повідомлення Показати цитований текст On 09/25/2024 8:25 AM EDT Matthew Rapaport <quineatal@...> wrote: Simple S11 tests of small HT antennas never yield expected results... When I test my mag mount on my car or J-pole hanging off the roof of a wooden porch (both at the end of hard-wired 10' coax and PL-251 connectors) I get expected values. SWR and resonance points (Smith chart) fall in the 2m & 70cm bands... But... When I try to test my HT antennas either connected to S11 directly or at the end of a short piece of coax (the VNA is properly calibrated under both conditions) lowest SWR and resonance are not in band, but 8-10 mHz outside them. These are good antennas too, Abbree, Flexi-whip, Nagoya, etc. They work fine ON the HTs... I'm thinking the proximity of the VNA itself and lots of other metal (grounded and not) in my test environment are to blame... Any suggestions?
Phillip Green Всі повідомлення цього користувача #38086 Actually, the readings of the nanoVNA are very close to the actual readings when comparing them to a professional radio shop test equipment. These portable dual, tri, quad band portable antennas are cut for a wide range of frequencies and not for a center frequency with all made in china. Please understand that frequencies are for all the world and for not the approved frequencies for the USA. I have been an emergency responder for forty years and have never seen a portable on radio antenna from china on the expensive Motorola portables ever near the working frequencies. A 2 meter antenna range is actually 136mhz to 174mhz and not within the USA ham band range of 144 to 148. So test will indicate different results. N4PWG переключити цитоване повідомлення Показати цитований текст On Sep 25, 2024, at 7:25 AM, Matthew Rapaport via groups.io <quineatal@...> wrote: Simple S11 tests of small HT antennas never yield expected results... When I test my mag mount on my car or J-pole hanging off the roof of a wooden porch (both at the end of hard-wired 10' coax and PL-251 connectors) I get expected values. SWR and resonance points (Smith chart) fall in the 2m & 70cm bands... But... When I try to test my HT antennas either connected to S11 directly or at the end of a short piece of coax (the VNA is properly calibrated under both conditions) lowest SWR and resonance are not in band, but 8-10 mHz outside them. These are good antennas too, Abbree, Flexi-whip, Nagoya, etc. They work fine ON the HTs... I'm thinking the proximity of the VNA itself and lots of other metal (grounded and not) in my test environment are to blame... Any suggestions?
Roger Need Всі повідомлення цього користувача #38088 On Wed, Sep 25, 2024 at 05:25 AM, Matthew Rapaport wrote: When I try to test my HT antennas either connected to S11 directly or at the end of a short piece of coax (the VNA is properly calibrated under both conditions) lowest SWR and resonance are not in band, but 8-10 mHz outside them. These are good antennas too, Abbree, Flexi-whip, Nagoya, etc. They work fine ON the HTs... This group has been around for 5 years now and you will find lots of informative discussion on many topics in the archives which you can easily search. About 2 years ago we had a long discussion on measuring HT antennas. Here is a link... https://groups.io/g/nanovna-users/topic/94460502#msg35249 Some more links on the subject.... https://groups.io/g/nanovna-users/message/29607 https://groups.io/g/nanovna-users/topic/102134224#msg34456
Eitan Tsur Всі повідомлення цього користувача #38090 Don't forget about tiger tail's; depending on the HT they may need one for repeatable test results and useability. Between brands and models the impedance of the radio may or may not be identical as well. On Wed, Sep 25, 2024 at 10:02 AM Roger Need via groups.io <sailtamarack= yahoo.ca@groups.io> wrote: On Wed, Sep 25, 2024 at 05:25 AM, Matthew Rapaport wrote: When I try to test my HT antennas either connected to S11 directly or at the end of a short piece of coax (the VNA is properly calibrated under both conditions) lowest SWR and resonance are not in band, but 8-10 mHz outside them. These are good antennas too, Abbree, Flexi-whip, Nagoya, etc. They work fine ON the HTs... This group has been around for 5 years now and you will find lots of informative discussion on many topics in the archives which you can easily search. About 2 years ago we had a long discussion on measuring HT antennas. Here is a link... https://groups.io/g/nanovna-users/topic/94460502#msg35249 Some more links on the subject.... https://groups.io/g/nanovna-users/message/29607 https://groups.io/g/nanovna-users/topic/102134224#msg34456
Matthew Rapaport Всі повідомлення цього користувача #38092 Thank you for that link and thank you all for the replies... I think all of you have addressed some aspect of the problem... More than one reason for the unexpected results. 😭 I appreciate all your feedback Matthew KD6KVH
Bruce Akhurst Всі повідомлення цього користувача #38099 Done to death regularly Highlights Ground plane availability and head proximity have a huge effect on antenna matching and performance Both must be replicated for valid transmit mode measurements Antennas for hand helds are an interesting and special case and different to base /mobile “SWR is bad because of feeder loss” (but there is no feeder) “SWR is bad because the PA gets damaged” (No. Commercial handhelds are specified for ANY SWR at any angle. Even Chinese stuff is usually ok until the attached clown tweaks up the power)! But given the choice the PA will often be happier with the high frequency side of the SWR dip than the lower side. What matters most for handhelds is the field and field strength that is created. In my early days as a pro Mobile radio designer the SWR dip was interesting but more a check /something to test batches for at goods in .. Mechanical strength, Field strength and pattern was was where we spent our lab time

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