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A big test of small antennas for amateur handheld radios 2m / 70cm

djbpm 4893 14
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  • A big test of small antennas for amateur handheld radios 2m / 70cm
    Hello everyone.
    Recently, I have measured several dozen handheld antennas and 3 car antennas in the amateur 2m and 70cm ranges in an amateur way.
    Here is the list:

    01 Retevis RHD771 (2.15dBi) Aliexpress RETEVIS Official Store
    03 Nagoya NA-771 (2.15dBi) Aliexpress?
    07 Yaesu VX-6R Factory attached to the radio
    08 Wouxun KG-UV8D Factory attached to the radio
    09 Harvest RH660S (3.0 / 5.0 dBi) Aliexpress BlueRadio store
    09skr as above but it was only extended to work at 70 cm
    partially so that the SWR is approx.
    as above
    10 Self-made on the pattern 771 Sam robilem
    11 Diamond NR-770H (3.0/5.5dBi) InRadio
    12 Nagoya NL-770H (3,0/5,5 dBi) HamRadioShop
    13 Nagoya NL-770R (3,0/5,5 dBi) HamRadioShop
    14 Nagoya NA-666 (2.15 dBi) ?
    15th Nagoya NA-771 (2.15dBi) ?
    16 Baofeng BFG-A-3 ?
    17 Baofeng UV-3 Fabryczna dołączona do radiotelefonu
    18 ICOM FA-S270C Factory attached to the ICOM E90 radio
    19 Baofeng DM5 Factory attached to the radio
    twenty Baofeng UV5 Factory attached to the radio
    21 Nagoya NA-771 ?
    22 Kenwood KRA-23M factory included with the NX-200 radio
    23 Kenwood TH-D74 Factory attached to the radio
    24 Yaesu FT-5D Factory attached to the radio
    25 Anytone 878 Factory attached to the radio
    26 Alinco DJ-G7 Factory attached to the radio
    27 Yaesu VX-2 Factory attached to the radio
    28 ICOM MARINE? Factory attached to the marine radiotelephone
    29 Kenwood NX-320 E2 (KRA-27?) 70cm Factory attached to the radio
    thirty ? Miniature something at 70cm Aliexpress
    31 Sagem 70cm ?
    32 Yaesu Standard Horizon CAT-460 Factoryattached to the radio
    33 MDVM HS DUAL Factory attached to the hotspot
    35 Diamond RH-771 ?
    36 Nagoya NA-771 ?
    37 Nagoya NA-701 ?
    38 ? without description, base similar to Wouxun ?
    While the originality of the antennas included in the factory with the equipment does not raise any doubts, it can be different with each other. If I was sure that a given antenna is a counterfeit, it would be marked.

    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm

    The measurement was carried out in 4 rounds, in which I measured the S1P parameters (including SWR) and the signal level emitted from each of the antennas under field conditions.

    S1P measurements with the NanoVNA-H4 analyzer:
    1. Antenna placed directly on the NanoVNA-H4, and measurement with the Analyzer in the hand, close to the head, held like a handheld transceiver.
    NanoVNA calibration took place directly on its socket in the frequency ranges 120 to 170 MHz and 400 to 470 MHz
    2. Antenna on the base with counterweights and NanoVNA measurement.
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm
    NanoVNA calibration was done on the base slot, eliminating the influence of the adapters used to connect the base. Ranges as above. If the antenna required an additional adapter, then this adapter was not calibrated, so the SMA barrel extends the line by 155 picoseconds, and the SMA - UC1 socket is 327 picoseconds, and this UC1 adapter has 43 ohms of wave impedance. The influence of these adapters is noticeable in the 70cm band, especially on the Smith chart, but it is not big and for the purposes of this test it can be omitted.

    Signal level measurements:
    3. Antenna on Yaesu VX-6 handheld radio and signal level measurement on base station.
    4. Antenna on a base with counterweights and a base on a Yaesu VX-6 and measuring the signal level on the base station.
    Measurements 3 and 4 were carried out at a distance of 185 meters from the base antenna, in an urban area, in a densely built-up housing estate, but in the field of optical visibility of the antennas. I walked about 15 meters with the PTT pressed at full power and the device at my head, just like I would normally use it to make communications. I tried to keep the device as vertical as possible so that the polarities of the antennas were consistent. There were no obstacles on the walking route in the immediate vicinity. In the case of walking with the counterweight base, these counterweights were placed a few cm above the head, so then the antenna was about 30cm higher than when broadcasting without counterweights, which could have a false positive effect in favor of the counterbalance system.
    At the base station, the signal was picked up by a Diamond X50N antenna installed about 10 meters higher than the towel rail, giving an angle of 3.1 degrees. The signal came through a 10 dB attenuator, an RTL-SDR tuner working with the SDR ++ application, set to minimum gain, all AGC off, sampling 1536 kHz, division / 8 giving 192 kHz. The spectrum was recorded to an IQ .wav file. The center frequency of the SDR was set 50 kHz higher than the handheld transmitter, and as a result, the recording showed a carrier signal with a frequency of 50 kHz. The recording was filtered with a 49 kHz - 51 kHz bandpass filter. After such a cleaned recording, the noise level was -59 dB. 0dB is the SDR overload level, so the results are in the range of -59 dB is the minimum level to 0 dB is the maximum level (they are negative).
    Each antenna transmitted for about 15-20 seconds, and from this time the average RMS level expressed in dB was calculated.
    An example recording chart opened in an audio processing program looks like this:

    A big test of small antennas for amateur handheld radios 2m / 70cm

    There are clear differences between the individual antennas. I've already selected sample 35 on it, then zoom in:

    A big test of small antennas for amateur handheld radios 2m / 70cm

    and I mark precisely the beginning and the end. You can see here that the signal level fluctuates as it travels. Then I use the statistical analysis function which gives me this information:

    A big test of small antennas for amateur handheld radios 2m / 70cm

    I am writing back Average RMS Power.
    The measurements with the hand towel were performed on the frequencies 144.9875 MHz and 434.9875 MHz.
    Measurements made from antenna No. 14 took place only without counterweights.

    Results for the 2m band:
    number Antenna Signature level
    out of hand
    SWR
    out of hand
    Impedance Signal on
    counterweights
    SWR from pw The impedance from the
    01 Retevis RHD771 -22.24 4.10 29.55 -55.18i -13.27 5.31 10.23-14.47i
    03 Nagoya NA-771 -21.94 3.83 49.01-71.55i -12.63 3.66 15.37-16.83i
    07 Yaesu VX-6R -25 4,61 29,72 -61,55i -19,7 5,74 09,87 -17,92i
    08 Wouxun KG-UV8D -26,5 7,11 31,67 -89,32i -26,91 18,19 06,68 -59,56i
    09 Harvest RH660S -9,88 1,02 50,73 00,60i -7,82 1,07 52,39 -02,17i
    10 Samoróbka 771 -18,52 1,22 57,99 06,95i -17,91 6,95 166.82 -169,83i
    11 Diamond NR-770H -8 1,23 51,12 10,63i -6,44 1,16 48,04 07,10i
    12 Nagoya NL-770H -11,59 1,79 68,49 -29,26i -9,59 1,78 64,28 -29,83i
    13 Nagoya NL-770R -8,36 1,52 33,20 -03,87i -6,55 1,41 36,06 04,67i

    number Antena Poziom sign.
    z ręki
    SWR
    z ręki
    Impedancja
    14 Nagoya NA-666 -30,18 7,85 26,56 -85,99i
    15th Nagoya NA-771 -21,19 1,92 59,32 -34,85i
    16 Baofeng BFG-A-3 -26,68 3,00 18,05 13,46i
    17 Baofeng UV-3 -28,78 4,43 17,65 -35,98i
    18 ICOM FA-S270C -26,87 3,96 31,44 -56,04i
    19 Baofeng DM5 -24,97 1,88 27,22 -06,15i
    20 Baofeng UV5 -27,9 3,04 20,18 -22,07i
    21 Nagoya NA-771 -24,68 3,79 43,70 -66,72i
    23 Kenwood TH-D74 -28,34 6,33 30,94 -81,16i
    24 Yaesu FT-5D -23,54 1,13 53,18 -05,61i
    25 Anytone AT-D878 -24,11 1,37 43,23 -13,06i
    26 Alinco DJ-G7 3pasma -26,69 3,63 69,47 -78,97i
    27 Yaesu VX-2 -25,88 1,90 43,98 -29,96i
    28 ICOM MARINE -29,62 7,75 27,11 -86,30i
    32 Yaesu Standard Horizon -29.99 11,44 23,36 -102,08i
    34 Astro 320 127cm -14,99 2,59 96,68 -50,43i
    35 Diamond RH-771 -18,99 1,72 85,63 05,67i
    36 Nagoya NA-771 -21,79 3,61 49,37 -68,29i
    37 Nagoya NA-701 -24,08 3,09 40,51 -52,58i
    38 Wouxun? -22.1 1.99 79.59 32.86i




    Due to the fact that the negative units of the signal level are not very intuitive, for the purposes of the graph, I added +31 dB to each antenna so that all the results were positive.
    A big test of small antennas for amateur handheld radios 2m / 70cm

    Results for the 70cm band:
    number Antenna Signature level
    out of hand
    SWR
    out of hand
    Impedance Signal on
    counterweights
    SWR from pw The impedance from the
    01 Retevis RHD771 -11.83 1.57 64.47 21.41i -14.45 1.66 63.37 25.36i
    03 Nagoya NA-771 -15.59 2.47 99.53 -43.50i -15.25 2,01 91,23 -24,50i
    07 Yaesu VX-6R -19,44 3,27 36,61 -51,99i -18,64 4,53 14,80 -28,28i
    08 Wouxun KG-UV8D -18,59 3,31 108,81 -72,83i -14,2 1,23 59,70 05,76i
    09 Harvest RH660S -14,54 1,31 63,95 -06,13i -14,62 1,37 64,10 -10.95i
    09skr Harvest RH660S skrócona -14,02 1,01 49,35 00,10i -13,79 1,04 51,90 -00,49i
    10 Samoróbka 771 -11,98 1,27 39,66 -01,93i -13,13 1,45 34,67 02,63i
    11 Diamond NR-770H -11,21 1,06 51,88 02,60i -10,52 1,22 42,50 -05,09i
    12 Nagoya NL-770H -13,61 1,63 30,6101.14i -11.59 1.85 27.22 -03.46i
    13 Nagoya NL-770R -20.55 2.36 50.72-44.59i -13.86 2.51 27.21 -26.67i

    number Antenna Signature level
    out of hand
    SWR
    out of hand
    Impedance
    14 Nagoya NA-666 -19.85 5.82 121.36-138.41i
    15 Nagoya NA-771 -18.07 5.02 244,36 -39,54i
    16 Baofeng BFG-A-3 -20,47 1,70 55,85 -27,88i
    17 Baofeng UV-3 -17,28 1,20 54,95 07,97i
    18 ICOM FA-S270C -22,52 3,38 30,10 -46,16i
    19 Baofeng DM5 -16,61 1,72 85,59 05,65i
    20 Baofeng UV5 -16,63 1,74 83,53 -13,37i
    21 Nagoya NA-771 -21,74 6,69 23,39 -70,37i
    22 Kenwood KRA-23? -18,64 2,06 70,31 -38,90i
    23 Kenwood TH-D74 -22,65 3,07 38,17 -50,25i
    24 Yaesu FT-5D -23,28 3,90 27,32 -49,26i
    25 Anytone AT-D878 -17,8 1,95 76,32 -32,73i
    26 Alinco DJ-G7 3pasma -23,07 2,42 40,57 -40,08i
    27 Yaesu VX-2 -22,47 2,70 43,26 -47,67i
    29 Kenwood KRA-27? -20,22 2,46 54,49 -48,29i
    30 Miniaturowa -22,68 1,84 51,83 -31,57i
    31 Sagem 70cm -21.9 3,71 183,21 -18,91i
    33 MMDVM HS DUAL -19,83 1,39 47,75 16,04i
    35 Diamond RH-771 -14,83 1,18 55,47 -06,71i
    36 Nagoya NA-771 -18,74 3,49 39,18 -57,91i
    37 Nagoya NA-701 -20,41 3,66 48,98 -68,74i
    38 Wouxun? -19,08 3,19 57,18 -65,15i

    Tu również dodałem +31 dB.
    A big test of small antennas for amateur handheld radios 2m / 70cm
    Conclusions:
    - The handheld radio must be able to withstand a very high SWR.
    - Handheld antennas of an acceptable length work much better in the 70 cm band than in the 2 m band.
    - The difference in the signal level in the 2m band between the weakest antenna and the strongest one was 23.72dB. So we would have to use 236 watts from the weakest antenna to get the same signal level from 1 (ONE) watt from the strongest. For the record decibel calculator
    - The typical "gain" of a handheld antenna in the 2m band is strongly negative and is in the range of -10 to -20 dBi.
    - Counterweights help greatly in the 2m band, while their use with a towel is impractical.
    - Telescopic antennas, especially the long ones, are very effective, but they break down quickly and can crackle. Example of Astro 320:
    A big test of small antennas for amateur handheld radios 2m / 70cm
    Finally, here are the Smith and SWR charts:

    01 03 07:
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm

    08 09 10:
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm

    11 12 13:
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm

    14 15 16:
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm

    17 18 19:
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm

    20 21 22:
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm

    23 24 25:
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm

    26 27 28:
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm

    29 30 31:
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm

    32 33 34:
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm

    35 36 37:
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm

    38:
    A big test of small antennas for amateur handheld radios 2m / 70cm

    I wish you distant communications
    djbpm

    Cool? Ranking DIY
    Can you write similar article? Send message to me and you will get SD card 64GB.
    About Author
    djbpm
    Level 22  
    Offline 
    djbpm wrote 487 posts with rating 82, helped 51 times. Live in city -. Been with us since 2003 year.
  • #2
    zgierzman
    Level 30  
    You know, I've read a bit about antennas, I get the decibels, I even have NanoVNA and can roughly use it.
    I studied your text three times before I understood enough to figure out what the author meant.
    Maybe you could change your post enough for even an average bafeng fan to know what's going on?
    And on top of that you throw the antenna "I did it myself" and nothing about it - maybe some article about this antenna? Did you do what you got, what didn't work, etc.?

    Yes, I know, the electrode is an advanced forum. But take it easy, since you're fasting no is on the forum: "ham radio / antenna construction / RF secrets" only in "articles", then you should take into account that the readers will not catch the nuances of the sentence: "You can see here that the signal level fluctuates with movement, and you can see the differences between the antennas. " if you don't post an additional comment.
  • #3
    ptero
    Level 22  
    "How did you impress me" :) Now I am asking for a summary in Polish :)
    Now, as a less advanced one, I will ask which antenna for "baofeng" on 2m would you recommend?
    Regards
  • #4
    Wikita
    Level 11  
    From the author's comparison of 2 m, the best antenna is No. 11, ie Diamond NR-770H -> the variant without counterweights gives us as much as -8 dBFS on the receiver, with SWR = 1.23 (which is decent because we have 1% reflected power).

    As for the article, it's a good job. It takes a lot of time to collect so much data :)
  • #5
    djbpm
    Level 22  
    zgierzman wrote:
    But I studied your text three times before I figured out what the author meant ... Maybe you could change your post enough for even an average bafeng fan to know what's going on?
    Now that you know what's going on, maybe you can help write it in a simpler way? This is my first entry of this type, I am not a Polish teacher. I did not want this analysis to go to waste and only a few people used it, because it was a lot of work.
    zgierzman wrote:
    But take it easy, since you're fasting no is on the forum: "ham radio / antenna construction / RF secrets" only in "articles", then you should take into account that the readers will not catch the nuances of the sentence: "You can see here that the signal level fluctuates with movement, and you can see the differences between the antennas. " if you don't post an additional comment.
    There is probably no such section, but there is very specific information here which fragment is incomprehensible. The horizontal axis was missing, at first glance you do not know what is on it, and it is time. In addition, I added more details, but it makes the whole thing even longer, so bad anyway. But is it better now?
    zgierzman wrote:
    And on top of that you throw the antenna "I did it myself" and nothing about it - maybe some article about this antenna? Did you do what you got, what didn't work, etc.?
    I also threw in there other antennas that do not know what they are. This article is not about the self-made, I don't want to water down the topic.
    ptero wrote:
    "How did you impress me" :) So now I am asking for a summary in Polish :)
    Now, as a little advanced one, I will ask which antenna for "baofeng" on 2m you would recommend.

    Zoom in on the chart A big test of small antennas for amateur handheld radios 2m / 70cm look at the green bars, find the biggest one. Then check if the antenna structure and its price are acceptable. If not, look for another tall green bar. The 770 type car antennas are the most powerful. They can be used on a handheld radio, although it is inconvenient and may break the antenna socket. The most powerful handheld antenna is the Harvest RH660S, but it is a meter long telescopic antenna, also bulky, and breaks down and crackles over time. We continue to fly so sharply down that it's a waste of words. Added to this is the problem of counterfeit products and repeatability of production. Note that I measured several NA-771 antennas and almost all came out differently.
    Wikita wrote:
    From the author's comparison of 2 m, the best antenna is No. 11, ie Diamond NR-770H -> the variant without counterweights gives us as much as -8 dBFS on the receiver, with SWR = 1.23 (which is decent because we have 1% reflected power).
    As for the article, it's a good job. It takes a lot of time to collect so much data :)
    Thanks for this comment, and for putting in the correct dBFS unit.
  • #6
    sq3evp
    Level 31  
    Congratulations on your willingness to conduct research.
  • #8
    tplewa
    Level 39  
    Good job :) Interesting results, although in some cases predictable ;)
    Once Jarek SP3SWJ took measurements with his MAX 6 and the results were also interesting :)
    A big plus, because after all, it's a bit of work to collect data (measurements) and process the results.

    btw When it comes to some comparison of the antenna efficiency, and even with coarse directional characteristics, you can measure S21 (then we have two antennas on the ports, one tested - the other is our measuring one) - that's something like this https: //www.rtl-sdr .com / measuring-the-radiation-pattern-of-a-yagi-antenna-with-a-nanovna /
  • #9
    djbpm
    Level 22  
    tplewa wrote:
    Good job :) Interesting results, although in some cases predictable ;)
    Predictably, but you were hoping to find something sensible up to half a meter.
    tplewa wrote:
    btw When it comes to some comparison of the antenna efficiency, and even with coarse directional characteristics, you can measure S21 (then we have two antennas on the ports, one tested - the other is our measuring one) - that's something like this https: //www.rtl-sdr .com / measuring-the-radiation-pattern-of-a-yagi-antenna-with-a-nanovna /
    I tried to measure similarly and in the case of hand antennas it does not work, because the cables become a counterweight, which has nothing to do with the way a hand antenna works normally. The impact of the full counterweight is huge, and the cable is also quite random and random, it depends on how the cable goes, so the results will differ significantly from how the antenna works in your hand. In the case of a stationary antenna, such a test makes sense. I tested it on counterweights and used the Diamond NR-770H as the receiving antenna, but as I wrote before, I got nice graphs, only useless.
    A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm A big test of small antennas for amateur handheld radios 2m / 70cm
    edit:
    I ordered 3 Retevis RHD771 (2x SMA-m, 1x SMA-f) because of their good performance in the 70cm band, and they came yesterday. Repeatability so-so. The S1P comparison looks like this:
    A big test of small antennas for amateur handheld radios 2m / 70cm
  • #10
    tplewa
    Level 39  
    djbpm wrote:
    tplewa wrote:
    Good job :) Interesting results, although in some cases predictable ;)
    Predictably, but you were hoping to find something sensible up to half a meter.


    All in all, as I mentioned once, the measurements of Jarek SP3SWJ were visible, I accepted it myself and use Nagoya 701 (the stick knows if they are originals or fakes).
    Mainly due to the fact that a short and flexible rally does not stick in a person's hips, etc.
    How it works - chewing rags from a towel on FM / DMR / D-Star or using APRS somehow gives advice :crazyeyes:
    As for the measurements so quickly - it's a pity to talk 8-O

    A big test of small antennas for amateur handheld radios 2m / 70cm

    I think I've come to terms with it and I don't even take such measurements :) Therefore, I am not surprised by these results :)
    At home, I have towels attached to Yagi 2m / 70cm DK7ZB (2 + 2el) just quickly made of tubes available in Castorama and printed elements https://www.thingiverse.com/thing:5328693 - which is basically some negligible costs and the problem of antennas from the bottom is solved ...
  • #11
    BOOM i ZONK
    Level 21  
    Do you know what I miss in this statement? Something as trivial as a tuned quarter-wave piece of wire just soldered into a plug.
  • #12
    sq3evp
    Level 31  
    Yes - such a simple basic antenna for comparison, such a simple "quarter".
  • #13
    djbpm
    Level 22  
    BOOM i ZONK wrote:
    Do you know what I miss in this statement? Something as trivial as a tuned quarter-wave piece of wire just soldered into a plug.
    The reference antenna is usually a half-wave dipole. But maybe I will test something else. There will be what, there will be time, why not. Such a quarter is easy to make, but the quarters work very poorly without a counterweight, so I would not expect success.
    The test lacks antennas from official distributors. If we buy from an official distributor, will we get a better product than from Aliexpress or not? You can always buy, check and return, although it's not fair ... but is it fair to say in the offer that the NA-771 has "Gain: 2.15dB / 3.0dB"?
    tplewa wrote:
    I think I've come to terms with it and I don't even take such measurements :) Therefore, I am not surprised by these results :)
    Apparently, these antennas used to be better. Owenduffy wrote that the antenna from 2008 is doing much better than the 2016 antenna Link And the fact that the samoróbka antenna no. 10 has better signal performance than the other 771s may indicate that it is worth adjusting such an antenna. The calculators say that an SWR of about 4 is only about 2dB less power in the antenna, and yet the differences are greater.
  • #14
    tplewa
    Level 39  
    In the past, there were probably fewer fakes, now it is difficult to know what is original ...

    This NA-701 like the original bought in a store in PL where the seller claimed that the original (has a QR Code). I also have Chinese versions with Ali and I can say that I do not see much difference. On the other hand, as I mentioned, it is not the best antenna, chosen on the basis of how most are good ... so at least let it not interfere with carrying the radio ;)

    On the other hand, what I mentioned, Jarek did these tests, as I remember quite a long time ago in Burzenin - then there were fewer of these antennas. From what I associate, he tested the antennas supplied with the radiotelephones, probably Baofeng or other rice and branded ones. Funny, it seems that the Chinese are better. I think I will write to him, maybe he has some more materials from these tests - because I can't find it on the web at the moment ...

    Yes, sometimes it is worth fighting with the antenna, but what I wrote on PKI is a very difficult topic in the case of a hand towel antenna. The trial and error method is more likely because it is difficult to measure it sensibly because when using a radio in real conditions, the antenna is often influenced by many factors. Although there may be some more sensible methods, at least I do not know them and I have skipped the topic of hand antennas ... I have access to an anechoic chamber to make measurements, but unfortunately it will not reflect the real conditions in which such an antenna works :(

    I see that you are passionate about building your own antenna, so with a bit of luck you may come to some interesting conclusions - such experiments are probably the only way ...
  • #15
    djbpm
    Level 22  
    Due to the fact that some people use stationary analyzers and try to connect manual antennas to such an analyzer with cables, I also did a test of how the antenna behaves when connected via a cable.
    Two antennas participated in this test:
    01. Retevis RHD771
    09. Harvest RH660S
    I only examined the 2m band.
    Conditions "without cable" the same as in the test from the first post. Here you can compare the repeatability of the measurements. I replaced the cells in the VX-6 battery, maybe because of this the signal is a bit stronger, the differences are below 1dB, so not that big.
    The cables are SMA-M SMA-F extension cords, one is 91cm RG402, the other is 5 meters RG223 connected to the first, 5.91cm in total. Radio in my left hand, cable going to my right hand, and in my right hand I was holding the antenna by the cable, in the same way as I had previously held the radio in this hand. In the case of the longer cable, it was partially coiled and held in the left hand with the radio so that it would not get tangled under the feet when "walking".





    Antenna Without the cable 0.91m 5.91m
    01 -21.65 -14.52 -20.84
    09 -9.08 -9.27 -10.78


    The conditions of measurement with the analyzer are the same, of course the radiotelephone replaced with the analyzer. Calibration of the analyzer in the place where the antenna is connected. (This compensates for the influence of cable transformation and attenuation)

    01. Retevis RHD771:
    A big test of small antennas for amateur handheld radios 2m / 70cm

    09. Harvest RH660S:
    A big test of small antennas for amateur handheld radios 2m / 70cm

    As you can see, apart from the transformation of the cable, there is also some other phenomenon that has a very large impact on the operation of the short antenna.
    So the question arises: How do you measure handheld antennas through the cable so that the results reflect reality? Is inis it possible at all?