How Do I Get a Better Antenna?

Discussion in 'Amateur Radio News' started by VK6FLAB, Dec 7, 2018.

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  1. WA6AM

    WA6AM Ham Member QRZ Page

    Note to self: Continue to find the fun and mystery in the hobby. And share it with those who show an interest.
     
    KD0CAC, W4MHZ, KC1FUU and 1 other person like this.
  2. KR3DX

    KR3DX Subscriber QRZ Page

    This demonstrates that they are all equally poor antennas. You should have compared them to a half wave dipole at the same height, you would have found that they have some front to back directivity, but the "gain" was essentially the same, or maybe a bit worse than the dipole.
     
    Last edited: Dec 9, 2018
  3. W4RQ

    W4RQ Premium Subscriber QRZ Page

    Whether you do have a good understanding of physics and math, or don't....
    The antenna(s) you use is the most important part of your station.
    Do some reading and do some research,
    Determine what you want to do in Amateur Radio
    Define how much room you have on your property, and what restrictions you have
    Search, read, listen, and decide what will best fit your location and work the best for what you want to do.
    Obviously you are not going to build a 160 meter Rhombic antenna on a city lot, but there are always alternatives.
    Maybe it would be good to have a discussion with some of the more experienced members of your local club?
    Draw on their many years of experience !
    Above all else, remember that EVERY Antenna is a compromise!
    and.......Good Luck to you,
    Rich W4RQ
     
    W4RAV likes this.
  4. K2JVI

    K2JVI Ham Member QRZ Page

    I couldn't agree more with Rich's (W4RQ) comments
    True just about every antenna is a compromise,but the "proof in the pudding" as they say is how does it perform in actual operation. And a bit or creativity goes a long way in the real world. Don't get me wrong, I'm all in favor of having at least a fundamental understanding of antenna therory/physiscs etc. this will help one understand the "why" behind how it works. Case in point about ten years ago I decided to revamp my small antenna farm. I looked at the DX engineering 43' vertical available at that time and did a "what if" -I said "what if I replaced that 43' vertical with a much longer wire and tried to make it high and as vertical as possible while still using the balun and the radial plate? So I did some research and even called DXE and spoke to one of their experts, he seemed to think that it would be more efficient than the 43' vertical radiator. So off I go-planted about 55 radials that ranged form 25' to 70' long-mounted the 4:1 balun at the base and threw about a 120' long wire an an obtuse L shape up thru two trees, with a height about 50' off the ground.
    Ran the Rg213 to my tuner and it's been working very well ever since. Like I've said before on a few posts, the old Nike slogan "Just Do It!" applies to many aspects of amateur radio
    Just Do It and 73's
    Bob.
     
    KC1FUU likes this.
  5. NN2X

    NN2X Premium Subscriber QRZ Page

    I did compare with Dipole for the 2o meter and 17 meter, all the usual gain and F/B.

    The key in this test, was to focus on comparing the MONO banders ( 3 separate manufactures for the Yagi Antennas), to the a HEX beam, (K4KIO).

    Not all 4 Manufactures are bad, matter of fact all are designed well, They key is the difference between 2 element (Hex) and 3 element (Yagi) is not measurable in the real world experiences. The conclusion is to stick with the HEX beam until ready to commit to boom length of 32 ft, otherwise, you will not see any difference (Measurable)...

    NN2X, Tom C U on the bands
     
  6. KI7M

    KI7M Ham Member QRZ Page

    Interesting 'round' quad on the picture on QRZ of your article. Per W6SAI (SK) it's the highest gain of the quad family. Also about the hardest to build for anything below about 2 mtrs. Try to build a 14.2 Mhz quad with circular elements as start considering the physics of that!

    I've been building antennas for probably 55 or more years and still don't understand the indept physics of them. That never stopped me. I have build many quads, yagi's, dipoles of one form or another, verticals and some others that the names escapes me right now. But a physicist could probably understand why things occurred I never did. Like lengthening a sloper antenna causing the frequency to go up? Don't know why but I've seen it happen more than once or twice.

    To heck with physics, just use the various antenna books as you may and go build using the basic formulas...468/F(MHz), etc. And have the fun of doing it yourself by your own two hands. Then maybe some day figure out why it worked.

    Quads are still my favorite antennas and when spider beams came along I thought someone just turned one element of a quad on it side and broke the full wave element in two. Reflector and driven element. Maybe the other set of spreaders got broke in a storm? Go build something and just have fun.

    Terry
    KI7M
     
  7. KR3DX

    KR3DX Subscriber QRZ Page

    Hi Tom,
    "All the usual gain and F/B" really says nothing about your comparison. You didn't state what difference, if any, that you observed between the dipole and the beams. Did you compare "by ear" or by S-meter reading? Most S-meters are very poorly calibrated, and even a 3db difference between antennas is only 1/2 of an S-unit on an ACCURATELY calibrated meter. If your mono-band yagis have full size elements and the spacing is optimized for forward gain, a 3-element yagi has, AT BEST, about 4db gain over a dipole when both antennas are the same height above ground. The gain of the yagi is at the design frequency and will fall off RAPIDLY as the operating frequency is moved a few 10s of kHz in either direction. If the yagi elements are NOT full size and if the spacing between the elements is NOT optimum, the gain of the yagi over the dipole will be significantly less than 4db when both antennas are at the same height. My guess is that all of your yagis and your hex beam have VERY little gain (if any) over a dipole at the same height. This is why you are seeing no difference between your beam antennas, they are approximately equally poor in their performance compared to a dipole. This assumes that ALL antennas are properly fed and have no feedline radiation. A little bit about antenna "gain" from W8JI:

    "The dipole is the basic building block of many antennas. A dipole does NOT have 2.2 dB gain over an isotropic radiator when the dipole is placed over earth. The dipole has about 8.5 dB gain over an isotropic radiator! Always remember this when you see antenna models over earth given in dBi. If the model over earth shows a "gain" of about 8.5 dBi, the model effectively has the same gain as a dipole. The notion that a dipole has around 2.15 dBi gain is only true for freespace."
    Source: http://w8ji.com/antennas.htm

    I looked up the "gain" for a commercial (almost $800) hex beam that is 22 feet in diameter, it is listed at 5.3dbi. That is 3db NEGATIVE "gain" over a full size dipole. You can't circumvent the laws of physics, ANY antenna that is physically smaller than a half wavelength and has its elements "bent", is at a significant disadvantage compared to half wave size elements that are "straight". I don't mean to sound harsh, but I believe in science, not in manufacturers' "specs", or anecdotal claims that "I worked lots of DX so it must be a good antenna", or some internet article posted by an "experienced DXer".

    73, Dennis
     
    Last edited: Dec 9, 2018
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  8. NN2X

    NN2X Premium Subscriber QRZ Page



    You are making way to much out of this...

    I purchased 3 mono banders...(Hygain Mono Bander, 3 Element 12FT boom), 2nd (Mosley Mono Bander, 3 Element 24FT Boom), and 3rd ( Force 12th Mono Bander) 4 Element Mono)

    I purchased a K4KIO Hex Beam

    I have a A /B Switch..

    Simple test

    Test 1 Receive: (Switch Hex Beam, and compare to Mono Bander) This was for receive tests...All the same...You could not hear any difference, S Meter was the same..What ever issue I had for accuracy, it would carryover...Simple Test, A & B switch

    Test 2 . Transmit, (Switch Hex Beam, and compare to Mono Bander) Transmitted a CW carrier to DX station, (In Europe, at Night Pacific), Very simple test, I asked the RX DX Station what is S reading, The same as the Hex Beam

    THE F/B was about the same, (Remember the K4KIO Hex beam is modified)

    I did this test for 3 months, and actually had Ham operators come over to see the test..

    It was me, who was very surprised!

    A simple test, That is the real world..

    Yes I could had rented an 8566 Spec An, But really, in an operation point of view you will NOT SEE A DIFFERENCE..
     
  9. KR3DX

    KR3DX Subscriber QRZ Page

    Yes, I understand your original post and your detailed explaination, and as I stated in my first reply, I still believe that the reason that you are seeing no difference between your 4 different beam antennas is because they ALL offer very little "gain" relative to each other or to a half wave dipole. In this post you didn't claim to have done a comparison test to a dipole. If you had, I believe that you would have noticed virtually no difference between the "beams" and the dipole.
     
  10. NN2X

    NN2X Premium Subscriber QRZ Page


    There was difference between the dipole, for sure, can see 1.5 S unit, sometimes, 2 but that is just relative. (No matter which antenna, Of course this was in the same forward direction)

    However, here is the KEY

    My Hex Beam set up costs about $500, Mast $100, and TV rotor $100... Total with cable and guy wires less than $ 800 / No concrete, no labor all myself..

    My Mono Banders ($500 for Force 12, $ 800 Mosley, $ 200 Hygain $ 400 Rotor, 1,200 Tower, $ 1,200 Installation (Labor) and $400 Concrete = $4,700

    So that is the bottom line, $4,700 versus $ 800...(With no noticeable difference, fact)

    That is my costs for both set ups, this is to only indicate it is NOT Worth buying any Yagi set up unless at least 32 ft boom (I am assuming one will see the difference at this point)

    I am admitting I wasted money on the mono banders set up! And passing my 4.7K experience to all who desires to listen!



    C U on the bands,

    NN2X,

    Tom
     
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