Loading ...
Sorry, an error occurred while loading the content.

264Re: Dual Band antenna recommendation?

Expand Messages
  • andyn1ksn
    Jun 1, 2011
    • 0 Attachment
      The tests I ran did not involve antenna efficiency or radiation, only the impedance match of the antenna to 50 ohms. I do not believe that grounding would play a role here, particularly since there is a calibraton procedure to null out effects due to cables and imperfections in the return loss bridge used. Since the antennas were positioned in a way that simulates their use on an HT, poximity to other bodies was taken into account, at least approximately.

      If the Nagoya NA-701 works just fine (as per your experience), great. I have no quibble with you on this. I may buy one myself. But the NA-702 is definately a total dog (as my data and on-air experience show), and two other models show poor matches, as well, so anyone listening should understand that your recommendation is for a specific model, not the brand in general.

      --- In UV-3R@yahoogroups.com, "g4ilo" <julian.g4ilo@...> wrote:
      >
      > I certainly agree with your main point. My concern was that you were suggesting that Nagoya antennas were not worth buying. I see no evidence to suggest that there is inconsistency in performnce between different Nagoya antennas of the same model which people have found to be satisfactory.
      >
      > As for the ground cable, years ago I did some tests of the Miracle Whip HF antenna and claimed that it worked quite well even without a counterpoise. I had many arguments with the HF Pack group who conducted tests that claimed performance was something like 20db worse without a counterpoise. Eventually it became clear the reason for my better results was that my FT-817 was grounded through the power supply negative line which was improving the efficiency of the antenna in the same way that a counterpoise would. Therefore I would suspect that the coax connection to your test instrument could provide an efficiency improvement similar to attaching a "tiger tail". I certainly would not want to discount that possibility entirely.
      >
      > Julian, G4ILO
      >
      > --- In UV-3R@yahoogroups.com, "andyn1ksn" <acp-smp@> wrote:
      > >
      > > Hi Julian. Thanks for your interest and comments.
      > >
      > > The ground side of the antenna was probably grounded through the coax shield to the instrument, but I don't see how this would affect the results, at least in comparing impedance matches to the antennas. And small perturbations in the holding position had minimal effects. Since the test results were consistent with my use of the antennas in the field, I am comfortable with them.
      > >
      > > Yes, generalizing on the quality of an entire brand of antennas after testing only three different models can be considered unfair, but I think it reasonable to conclude that such a brand is at the very least unpredictable in quality and performance from model to model. (The NA-702 was particularly horrible on UHF.)
      > >
      > > If your field experience shows that the model NA-701 performs on a par with Yaesu stock antennas, then it performs well enough to be USEABLE, as were several antennas in my study. After all, prior to the study I had used them all (except the NA-702 which was obviously horrible in use right out of the package).
      > >
      > > My main point was that not one single dualband antenna I tested had what I would consider good matches on both VHF and UHF. This surprised me. The main consequence is that when we use our HTs, we are often using much lot less RADIATED power than we think we are.
      > >
      > > Cheers,
      > > Andy N1KSN
      > >
      > >
      > > --- In UV-3R@yahoogroups.com, "g4ilo" <julian.g4ilo@> wrote:
      > > >
      > > >
      > > >
      > > > --- In UV-3R@yahoogroups.com, "g4ilo" <julian.g4ilo@> wrote:
      > > > >
      > > > > I found the NA-701 performs on a par with the stock rubber duck antennas from Yaesu (and better than Kenwood antennas which seem to resonate aroound 160MHz). I did find the single band 2m antenna that came with the UV-3R performed about 3dB better than the NA-701. I have not found any other antenna that size which performs that well, but it does not seem possible to find a dual band antenna that does not sacrifice performance without gooing for something much bigger.
      > > >
      > > > Ignore that. I misread my writing and the comparison was with the NA-401 not the 701.
      > > >
      > > > The NA-701 does perform similar to dual band rubber ducks from Yaesu. The single band VHF antenna with the UV-3R is about 3dB *poorer* than the NA-701. But it is half the size.
      > > >
      > > > Julian, G4ILO
      > > >
      > >
      >
    • Show all 21 messages in this topic