If the antennas are used for receiving only (which is probable), then it doesn't make much, if any, difference if they're at the top end of the desired range. If the antennas are cheaply made then you're lucky that they resonate near where you want them to. Question also arises as to how accurate your measuring equipment was for the test. On the whole I would say you got what you wanted. Any antenna that is only 19 inches long that's used for 10 or 11 meter reception is bound to be a much less than ideal performer.
I wonder if they tuned it at the factory over a good groundplane? Not much of a ground with just the HT case or measuring device.
If you attach at least one 7-8 foot radial (near 10m band) wire to the ground of the HT, or your measuring device, does it make a difference? Although of course this limits the portability unless you are stationary-portable.
It wouldn't make sense for the antenna to be tested over a perfect ground plane, because an HT isn't one and usually isn't over one. But I like counterpoise wires and I use them sometimes, when stopped by the trail. There doesn't seem to be much frequency shift due to the counterpoise. I'll measure it and post it when I get the chance.
I have tested a number of HT antennas over the years and have never been impressed with their SWR characteristics.
But I take solace in the fact that HTs are usually OK with that. Think about a radio on your belt with the antenna mashed up in you side. The SWR is NOT going to be good at all. Same for if you are using it in a vehicle, holding it by your head, ETC. But the radios do not care. You could transmit into a complete open and the radio would probably not fail. And I have not noticed any HTs drop their power if transmitting into a bad load. They are built for it. While it is nicer to have a perfectly tuned antenna, the truth about HTs is that it is not possible. And any manufacturer hopefully understand that and has designed their radio accordingly.
Now, if you are using this antenna on say an FT-817, then Yes, SWR is critical as these do not seem to like high reflections.
Fact remains that if you're trying to get decent results with a 10M HT and its antenna is resonant 10 mHz higher that, say, 29.60 mHz you'll have nearly as much power coming back as is going forward and the results are going to be lousy. Best bet would be to get a long extendable whip with a loading coil which would have at least half a chance of doing the job you need done. It's also possible that one or more of the HT antenna companies is still making 10M shortened HT antennas, and while the performance might be less than ideal at least they won't heat up and possibly damage the final amplifier in your HT. You will pay for good quality control on items such as this but it would seem to be the only choice available.
Well, 29.6 isn't 10MHz away from 34MHz. It is JUST over 4MHz which happens to be the same size as the 2 meter band. And many HTs use a single antenna that easily covers all of 2 meters.
And commercial radios commonly get used from 151MHz to 170MHz with a single antenna.
While bandwidth issues do arise with a 10 meter HT antenna, you really need to look at the broader picture. Firstly, Loss as we understand it with fixed or mobile radio stations does not exist. There is no feedline present on an HT, so we have no feedline loss.
2ndly, if you are very worried about SWR when associated with an HT, put a bunch of rubber ducky antennas on an MFJ analyzer and start sweeping them. Pretend that the analyzer is an HT (it is actually MUCH bigger than an HT) and just move it around like you would your radio. The SWR from any one point can change rapidly from resonant to WELL over 10:1. Put it by your head, then place it by your belt, then just walk around in your house or sit in your vehicle. And this is all at VHF (2 meters). Give it a shot with a HEAVILY loaded 10 meter ducky. This will be even more finicky. Near field objects will screw with it.
Wanting the lowest SWR with an HT is a noble cause, but it is impossible to get with an HT. Sure you can pull the antenna off and tune it over a groundplane, but that is completely unrealistic. I don't care what the ideal results are, I want to know what the actual field results are. And any manufacturer who is worth a darn has provided for safety margins in these radios. I have never had the finals on an HT go out, and neither have most hams.
If you REALLY want to get the best SWR, carry a small roll up dipole and string it in the trees when needed. They are small and would work a LOT better than the ducky. Or if you want to remain mobile, look at hfpack.com. Those folks understand pedestrian mobile ops on HF bands, and you don't seen their antennas hooked to HTs. They are bolted to pack frames and have inline tuners.
I have MFJ telescoping whips for the FT-817. They are manufactured a little high in frequency, too, but they are available on nearly all bands and are adjustable. So I use the 21 MHz antenna on 24.9 MHz, etc. They are hard to use while walking along, though. Good when I stop beside the trail.
Does anyone have a suggestion for antennas for 10M and 12M that would fit on an HT, using a BNC at the base?