Using FT8 to demonstrate Antenna Orientations

Discussion in 'Amateur Radio News' started by KM9G, Oct 6, 2021.

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  1. KM1H

    KM1H Ham Member QRZ Page

    This was supposed to be attached to Post 15!

    I started with 3 scrapped CB 5/8 verticals found at the town transfer station or hamfest years before the Chinese Flu.

    Removing the matching coil inside the base and adding a short #12 wire in place I make the aluminum element a 1/4 wave on the lowest frequency. Using a stepladder next to a 10' TV mast found curbside and semi stabilized inside a concrete block and finished off with some Dacron rope guys. Then attach 4 #12 stranded and insulated elevated 1/4 wave radials and tweak to resonance using a MFJ 259B. (I did this long before the nanoVNA came along)

    Then fold over and attach another #12 for the next higher frequency to the center element using ~5" long sun resistant plastic standoffs. Add radials and tune. For the next highest band attach the standoff on the other side, etc, etc.
    The standoffs are attached with self tapping screws and a hole for the wire.
    When finished the antennas are clamped to 20' heavy duty TV masting, separated enough to not interact and using a HB relay box to a single RG-6 quad shield coax elevated thru tree branches back to the house. Decoupled at the antennas and again at the relay box and again at the house entrance with one each Fair Rite 2631803802 toroids available from most major distributors such as Mouser, Newark, Arrow, etc.

    All materials were from metal scrap yards, town "dump", curbside, fleamarkets, yard sales, and hamfests. KIC= Keep it cheap.

    The antennas here are for 10/12/15; 17/20; and 30/40 and used mostly on vintage boatanchor gear on plate modulated AM (Johnson/Collins) plus some CW and SSB with a HT-32B and CE 100V.
    Working others, including DX when the bands cooperate is no problem using a well built vertical, and not some compromised, poorly designed, overpriced POJ. As sunspots increase the long haul paths favor low angles and there the verticals rule the roost. Also fine for local roundtables, etc.

    I have no way of making instant comparisons with the main station wires and yagis but Ive worked all over the US and the world with ~100W and minimum audio processing and shaping from NH which is seldom known for its good propagation. Much more power is available when deliberate QRM needs a lesson.
    W1YW and M1WML like this.
  2. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    I'm almost ashamed to be an amateur radio operator/ after reading some of these post.

    73 from,
    The K0UO " Rhombic Antenna Farm" 2 miles of wire in the Air & On the Air daily
    W2CPD, N1IPU, KM9G and 4 others like this.
  3. DO1FER

    DO1FER Ham Member QRZ Page

    Some people in this threat talk about that FT8 is good for a comparison and to see what HF conditions are at the moment. But I think its false. The problem of FT8 is, that only the computer is able to decode. And often a human voice is in this given conditions no to hear. So FT8 is just for to catch whispering stations which are there for the moment. They are not already available and have to be sort out for the comparison. Because for a comparison it only make sense to record the constant available stations for to see the coverage area.
    M1WML and PU2OZT like this.
  4. M0TTQ

    M0TTQ Premium Subscriber QRZ Page

    Digi modes are useful indicators, it doesn't have to be WSPR. I have been doing a series of tests on FT4 in the mornings on the path to VK, and when I have more data I expect to find some interesting things. Most of the things people are criticising digi modes for in this thread are precisely the things which make it interesting for the study of propagation.
    M1WML, KC7ZXY, KM9G and 1 other person like this.
  5. KM1NDY

    KM1NDY Ham Member QRZ Page

    A few more thoughts on this topic that fascinates me:

    1) The fact that there were 1.2 million FT8 signals counted over the last 2 hours worldwide vs. <10000 wspr signals may make FT8 the superior mode for demonstrating propagation despite the inconsistent reception of individual stations.

    2) I think that some of you will find that the scientific-minded amongst us see tremendous potential in experimentation found within these datasets. It is possible to control for and compare many propagation variables lending to the citizen scientist niche of ham radio.

    3) While some of you may consider antenna propagation theory a settled science, it seems to me that not every antenna I have erected has bothered reading the textbook.

    4) I have looked at ssb vs. wspr propagation, and while mine is a very crude analysis, I was still surprised at its similarity in pattern. I posted about it on another thread a while back.


    Figure: # of signals detected in last 2 hours from PSKReporter:

    M1WML, KC7ZXY, KY4GD and 3 others like this.
  6. W1YW

    W1YW Ham Member QRZ Page

    You can't do an experiment without a control.

    I am "scientifically-minded". There is zero potential for learning from these data sets without robust experimental protocol. None here.

    This 'experiment (sic)' was incapable of concluding anything.
    Last edited: Oct 8, 2021
    M1WML, WN1MB, AC0OB and 3 others like this.
  7. PU2OZT

    PU2OZT Ham Member QRZ Page

    Alchemy, metal transmutation, back to sorcery, they should call themselves...
    ...using non-stop lines of code they have no idea how it works, yet less how that spreads.

    Random luck
    vs ​
    skills and science keeps gambling consumers forever happy.
    Awards granted for that, the last straw.

    M1WML, WN1MB and K0UO like this.
  8. N3RYB

    N3RYB Premium Subscriber QRZ Page

    Why do we need to stay under 50W for FT8?
    M1WML, KK2DOG and KM9G like this.
  9. DO1FER

    DO1FER Ham Member QRZ Page

    I wasnt critisising the intresting study of propagation in this thread when using digimodes. But all this start with a video and how to compare different antenna designs. So it passed the topic.
    PU2OZT, M1WML and KM9G like this.
  10. W1YW

    W1YW Ham Member QRZ Page

    In many cases, the environment is part of the antenna simulation modeling. Some terrains are not easily modelled by software (free) to hams however:) Certainly ground types are easily modelled:)

    But you know this:)
    PU2OZT and M1WML like this.

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