In praise of reference antennas

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by WB5YUZ, Mar 15, 2019 at 4:49 PM.

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  1. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    Reading a recent thread on end-fed antennas, I wondered what the OP must have thought about the seventeen (and counting) pages his original question had generated. After all, he only wanted to know which of two different types of antenna was better!

    It's not really a simple question, of course, it just seems to be; and those of us who are not professionally-trained engineers will be waiting through an infinite number of solar cycles for a simple consensus phrased in terms we can understand.

    So, what's the non-professional ham to do? I personally find solace in reference antennas. Not carefully designed and constructed test antennas in an-echoic chambers, intended to make absolute measurements, but rather simple antennas that are easily made to work well, intended to make relative comparisons. The 1/4 vertical with an adequate radial field, and the conventional center-fed dipole, are two good examples.

    With a dipole or vertical up and operating properly, the non-higher-educated ham can and should use it for a while, and get a feel for what desired signals, and what we naively called "band noise" in a bygone era, sound like on it. (If Amelia Earhart had only acquired this skill, she might have made to Howland, after all...).

    That way, if a new antenna is constructed, the ham who is less-trained, such as I, has simply to compare the new antenna to the reference one. Does the new antenna perform less well than the reference one to the extent that it is immediately noticeable? Then it was constructed/deployed improperly, is the wrong type of antenna for the desired service, or (St. Yagi of Uda protect us!) a bad design sold by greedy and wicked men for their own emolument.

    (And, I will keep reading those threads. Just because you can't understand everything doesn't mean you can't learn anything!)
     
    NH7RO, AI3V, KD6RF and 1 other person like this.
  2. N8CMQ

    N8CMQ XML Subscriber QRZ Page

    Your post makes good sense, and would give an inexperienced person experience they need to make good decisions.
    And by reading and looking up what you don't understand, you would learn what highly experienced people were trying to convey.
     
    NH7RO likes this.
  3. WB5WPA

    WB5WPA Ham Member QRZ Page

    Put up the two antennas and switch between the two, soliciting on-air signal reports; I have done that quite often, and one gets immediate feedback ...

    There are more advanced ways to compare (and get numerical results) two antennas (like, simultaneously xmitting with 2 rigs using WSPR) , but, I'll save that for a later date.
     
    NH7RO, KD6RF and WB5YUZ like this.
  4. KL7AJ

    KL7AJ Ham Member QRZ Page

    A properly constructed vertical antenna is indeed a good reference antenna....it is what is used at WWV/WWVH. I recommend looking at the NIST site which describes the reference verticals in detail.
     
    NH7RO and KD6RF like this.
  5. KL7AJ

    KL7AJ Ham Member QRZ Page

  6. WB5WPA

    WB5WPA Ham Member QRZ Page

    re: "So, what's the non-professional ham to do?"

    Hmmm. Nice thought, but, out of bounds for a "non-professional ham" ?
     
    NE1U likes this.
  7. WA7ARK

    WA7ARK Ham Member QRZ Page

    I have taken comparing antennas to the extreme. I presently have four different antennas which receive on 40m:
    160m horiz loop, 50ft agl, 556ft long.
    40m invV, apex height, 55ft agl
    40ft long, 2" dia, vertical, standing on a metal roof, remote tuned, tip height is ~62ft agl.
    Antenna Under Test: RA0SMS mini-whip(receive-only) on a grounded 10ft stick of 1/2"EMT conduit.

    Whenever I work on a new antenna, I put it up and compare it to the other three. That is how I learned that the vertical is rarely the best. Usually the loop is. On a few occasions, I get a stronger received signal on the InvV. The best SNR is always on the loop.

    To compare received signals, I can switch rapidly, even in mid word to average out QSB. To compare transmitted signals I use a distant webSDR such as Northern Utah or KFS, or the ones back East. Most have the ability to plot the received signal level (in db) vs time, like a strip-chart recorder.

    To eliminate QSB, I built an Arduino-based "keyer" that alternates "dits" and "dahs". It also controls a relay that switches between two antennas, so dits are antennaA while dahs are antennaB and provides sequencing to eliminate hot-switching while transmitting. By recording the received signal strength for a few seconds at the chosen webSDR, I can easily see the difference in received signal strength just by looking at the "dits" and "dahs".
    That way, I can put the remote webSDR receiver into a narrow CW bandwidth mode, which improves the resolution.

    btw-I am still evaluating the Mini-Whip. On HF, it is typically down ~1 S-unit compared to the loop. However, it absolutely shines at VLF. For example, WWVB is S9+10db on the Mini-Whip, and just barely detectable on the other three wire antennas...
     
  8. KL7AJ

    KL7AJ Ham Member QRZ Page

    Not at all...the WWV antennas are very simple...just carefully constructed (and measured)
     
  9. K0UO

    K0UO Subscriber QRZ Page

    This is just a hobby not everybody can have a gigantic antenna Farm, with multiple antennas, so put up what you can and use what you can. Most importantly, have fun with it!!!
    One thing for sure the more antennas that you have, the better. Even within a few minutes band conditions can change considerably and you'll see changes between two antennas. So having reference antennas will certainly be an asset. It can also be fun and show you things about propagation and how your setup is working.

    But Remember this.
    The best antenna is one that is "In The AIR & On The AIR" !!!!!!! I challenge everyone to call CQ once in awhile you might be surprised at who comes back to you.
    K0UO Rhombic and Vee Beam Antenna Farm. https://www.k0uo.com
     
    K2CAJ likes this.
  10. K8JD

    K8JD Ham Member QRZ Page

    Who uses an antenna has a great effect on how it is rated.
    A survey.
    Ant one a QW vertical with 50 radials . Ham reporting ; net control for a HF regional net. This antenna is lousy, the check ins are drowned out by DX signals.
    Ant two a HW dipole at 0.2 wavelengths high , ham reporting; a DXer . This antenna is lousy, all the Weak DX is drownded out by regional signals.
    It's true that you can do better with more antennas. I currently have single band antennas up for 160, 80, 40 and 12 M, and a multibander that covers 5-18.1 MHz. This varies as I add and delete antennas to experiment with new ideas.
     
    Last edited: Mar 15, 2019 at 7:13 PM
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