Best QRP Antenna for Field Day

Discussion in 'QRP Corner' started by KK4NSF, Dec 9, 2015.

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  1. KA9UCN

    KA9UCN Ham Member QRZ Page

    This is a long one but here is my 2 cents.

    I am in agreement with VWM on almost all except in the case of traps. I do think that they most certainly do have a place in QRP. Traps are something where if 3 people discus them there will be 5 opinions. The trick to a trap is Q. Make it to low and it becomes wide and does not perform well. Make it two high and it becomes very narrow and sharp with high circulating voltages and currents. So the trick is in the design. There are some very good traps on the market if a person chooses. Very high quality traps are not hard to build. I have built many over the years. The one type trap I would avoid at all cost is a coaxial trap. I have found them to be for most purposes useless. One I would shy away from is a cored trap weather it is ferrite or powdered iron. The advantages in size but does not justify the disadvantages. There are many.

    I like the yoyo idea earlier mentioned on another thread as it can be tuned on the spot to resonance weather as a long wire, loop or conventional dipole in any configuration.

    The thing about resonant antennas is they work every time with consistent results. Is it best for your situation? You will decide that.

    Health has been a problem lately but if all goes well this field day I will be on the lawn QRP battery operated with a home brew multi trap dipole probably fed with RG8. The reason being is location. I am in the mid-west (Indiana) so a good east west bidirectional dipole is needed.

    As for wire size I will use what I have as long as it is mechanically sound. I don’t care from an operational stand point what diameter the wire is. At HF it makes no real difference as to performance or band with. I am not a bit worried at running QRP or QRO on a resonant antenna. In my case I have a lot of no. 10 stranded. It is a bit heavy but the price was right, $0.

    If I was portable go station and did not want to go the trap rough I would with the YO-YO and set it up as terrane dictated.

    As for antenna tuners. I have had many and have in short order disposed of them. There use is very limited. In my opinion they are a waste of both signals in and out and have no place in QRP.

    As for gain antennas and portability. I like the idea of a multi wavelength loop in a diamond configuration. I have never used this type of antenna as per design to achieve directivity. I have used multi wavelength loops with no forethought as to directivity. If a lobe was favorable I used it. At the time of a multi band loop I had other antennas up so you use the one that works best at that time. However with a compass and some forethought a multi band loops lobes can be predicted and used with considerable gain at the cost of deep nulls in the pattern.


    Joe KA9UCN
     
  2. W7CJD

    W7CJD Ham Member QRZ Page

    I keep asking for modelling, so people can see that.

    For example, loop antennas:

    Is the lobe pattern that much different for each different band?

    The change for height would be helpful.

    Then, multiples of wavelength.
     
  3. KI6J

    KI6J Ham Member QRZ Page

    The best portable antenna is going to be put up by the person with the best rigging skills. I figure just about every shape that wire can be twisted has been modeled to death. Can you get two pulleys hanging from trees at 60+ feet, tilt up a 40 foot sectioned mast, or hang hang a couple hundred feet of wire from flimsy fly-rods stuck in sand? These are developed skills, mot some magic formula that makes it all easy.
     
  4. W7CJD

    W7CJD Ham Member QRZ Page

    There is also the rationale of cost-benefit, that includes effort for not much result.

    If already modelled, where can we see that?

    I put up links, when I find helpful information.
     
  5. KI6J

    KI6J Ham Member QRZ Page

    I put up antennas.
     
  6. KA9UCN

    KA9UCN Ham Member QRZ Page

    I wish I could help with the modeling but I do not have any inclinations to learn and use a modeling program. Too much other stuff going on at this time. I hope someone might model a diamond shape loop.

    To the question of is the lobe pattern that much different for each band? Yes.

    If it is 1 wave length it will be Omni directional. This is the part where I am not 100% certain. At 2 wavelengths it becomes a butterfly pattern, at 3 the lobes are mostly parallel to the wire, at 4 you have a pattern with 8 major lobes and the pattern becomes quite complex. This is how a loop can be used as a gain antenna. If someone could model the loop then the angles of the diamond could be determined for max gain. Loops can be very easy to build but size in relationship to frequency will most defiantly affect the pattern of radiation.

    Joe KA9UCN
     
  7. W7CJD

    W7CJD Ham Member QRZ Page

    I have put up antennas sonce I was 15 years old.

    I can do better.

    I have much the same situation, as you.

    I have 7 computers, each one already purposed.

    My custom-build PC is for processing large format photography RAW files.

    I am not pulling the Plextor Barracuda hard drives to put in my two reserve Plextor Barracuda hard drives and another operating system to have a "second" custom-build PC, to find out if I am reasonably proficient at running antenna modelling freeware.

    I am also not going to purchase a computer for Excel that alone requires 3 GB RAM, plus Microsoft DirectX 10 and a Microsoft compliant DirectX 10 graphics processor that has 64 MB of memory, so I can run a small program of antenna modelling freeware, or not.

    I would have to get reasonably proficient on the software, to begin.

    I am renting a house and I am building my house.

    That said, I will keep looking for the antenna modelling I can find, and, keep asking.

    I am determined, because people need to see antenna modeling like that, then choose build or buy for their situation and/or their terrain.

    It is absolutely pathetic, that so many people have their hobby interest ruined, by bad choices about antennas.

    Many plod along, and never find their enthusiasm for the radio amateur hobby again.

    "The bands are dead".

    Maybe it is your antenna?

    If anyone wants to discover how much there is available in this hobby, the antenna is essential.

    If they only want to consistently show up on the local net, the choice of antenna and how to deploy it should be straightforward.

    If it doesn't become obvious, and there are two or three choices, then let the questions have that starting point.

    I did find this:

    http://ve3vn.blogspot.com/2014/01/narrow-diamond-loop-for-40-meters.html?m=1

    I put on another thread, modelling showing the effect of feedpoint.
     
  8. W7CJD

    W7CJD Ham Member QRZ Page

    I am interested in antenna efficiency.

    For Field Day, I am near a parking lot, there are other radio amateurs helping each other to set up.

    Here is a reputably efficient antenna, avoiding losses, so those QRP watts and QRPp milliwatts do not disappear in losses.

    Lazy H

    http://techdoc.kvindesland.no/radio/antennas/20061010170744620.pdf
     
  9. W1VT

    W1VT Ham Member QRZ Page

    My best and most popular QRP antenna for FD is a 6M beam! There are often E skip openings during Field Day. There is also a lot of locals that can be worked in New England, particularly if you go up to a big mountain like Mount Equinox. I have a little 2 element Yagi with a 4x2 ft center section with removable element tips that is great for casual operations. I also have a big 4 element Yagi for operation either at home or a serious effort in the field.

    To add to the fun I have a homebrew SSB/CW QRP rig with a big tuning knob and a high dynamic range receiver. It uses a pair of high level diode mixers in a phasing configuration to achieve a two-tone third order dynamic range of 100 dB and great audio! None of the birdies and signal processing artifacts that plague most commercially available equipment.

    Zack W1VT
     
    Last edited: Jan 5, 2016
  10. W7CJD

    W7CJD Ham Member QRZ Page

    Did you build the little 2-element yagi?

    Maybe you would start a thread, to share your DIY transceiver?
     

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