EH Antenna – experiences

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  • #11308 Reply
    om2amr
    Participant

    Hello,

    Does anyone have experience with the EH antenna on KV ? I have limited spatial options and even a small vertical would be worth a try. I'd just like to know, Has anyone tried it here?.

    Thanks

    73!

    I work OM2AMR

    #13555 Reply
    OM7AC
    Participant

    Hi. Before three,four years ago I constructed an EH antenna at 14 MHz. It was on a PVC pipe with a diameter of approx. 5 cm. K tomu 2 times the required number of turns. I had it lying in the corridor in the block of flats. I made a CW challenge with the TCVR FT897D,with a power of about 70W. I was surprised,when the F4 station called me and we did a complete cw qso. I didn't deal with these antennas anymore. i atenuator a kusok drotu,whether it was a huge coincidence,or is it a rule,that this is how they work. But I think,that if it were a rule,so references would often be published. Try and see. There is a strong elm field near them when broadcasting. I finally gave it to a friend. i atenuator a kusok drotu,whether he used it for some experiments. PA GI7B

    #13556 Reply
    om2amr
    Participant

    Hi Igor,

    thank you for the info. I read a lot of positive things on the net, but also negative references, that's why I was interested, Has anyone actually tried it here?, how tp listens and broadcasts.

    In any case, I'll probably try it. EH and 80m to the balcony HI HI.

    I hope, that I will not light the HI street lamps.

    I work OM2AMR

    #13557 Reply
    Anonymous
    Guest

    @om2amr wrote:

    Hello,

    Does anyone have experience with the EH antenna on KV ? I have limited spatial options and even a small vertical would be worth a try. I'd just like to know, Has anyone tried it here?.

    Thanks

    73!

    I work OM2AMR

    For limited spatial possibilities, read about this antenna: https://www.cq.sk/modules.php?name=News&file=article&sid=910
    I don't know a radio amateur, who would seriously use the EH antenna !
    you 73 !
    Fairy, OM3CAQ

    #13558 Reply
    OM0AAO (OM0A)
    Participant

    I know, it's Michal OM0ABE. The main reason is, that his QTH is in the mountains above 1500m and freezing, wind and lightning (the surrounding area is poor land) they destroyed other dipole-type antennas. The antenna is said to behave well.

    I'm watching, that few radio amateurs think about the location, resp. the suitability of your QTH. For example, there is a difference, whether we place the GP in the garden or on a 30m high block of flats.

    Fingers crossed for implementation!

    #13559 Reply
    derick
    Participant

    Znamy worked with EH,but eventually found out,that the LOOP magnetic circular antenna with a diameter of approx. 1 m is much better. It is quite difficult to build a vacuum, dielectric, etc. One manikin in Germany sells them in small series,but it is quite expensive. Almost 300e including postage. I found it locally under a slate roof and it works really well. About 2s less than a full-size antenna.
    Of course, the best results are from 14 and up

    #13560 Reply
    om2amr
    Participant

    @OM0AAO wrote:

    I know, it's Michal OM0ABE. The main reason is, that his QTH is in the mountains above 1500m and freezing, wind and lightning (the surrounding area is poor land) they destroyed other dipole-type antennas. The antenna is said to behave well.

    I'm watching, that few radio amateurs think about the location, resp. the suitability of your QTH. For example, there is a difference, whether we place the GP in the garden or on a 30m high block of flats.

    Fingers crossed for implementation!

    Hi, can you please send me a contact for Michal ? I would like to exchange some experiences with him.

    Well thank you !

    I'm working

    #13561 Reply
    Anonymous
    Guest

    Hello, I experimented with the EH antenna for a long time and the results were miserable. That's why I made a Rock Loop type magnetic antenna, which I was satisfied with. From a sailing boat in Croatia, I made the longest connection with a ship in the Baltic and with Moscow on 14MHz with FT-817 operating PSK31. For PSK31 operation, the FT-817 can only be used with a power of 2.5W. A great advantage of the magnetic antenna is the low interference during reception. I have a description of the antenna on pages.

    #13562 Reply
    Anonymous
    Guest

    I used antennas of the EH type and made them structurally for bands from 80m to 6m.
    They have their design limitations and they have their pain points and there are also problems with the strong EM field near the antenna.

    Structurally, they have proven to be the best for the greater stability and VF properties of the polyethylene pipe, polypropylene. I also tried PVC waste pipes, but with outputs of around 100W, problems arose from HV/VF conductivity of the filling in these PVC plastic pipes.
    PPR water pipes have better VF properties.
    However, they are harder and less strong.
    They can be purchased in diameters up to 125 mm directly from the warehouse in a length of 4 m, for example, in BA at the company empiria.

    For example, the EH antenna for the 80m band with a pipe diameter of 75mm worked for me.
    The length of the EH dipole is 2 x 80 cm thanks to the construction material Al sheet.
    I rolled the sheet to a slightly smaller diameter on a rolling machine ( in tinsmithing)
    Galvanized Fe sheet can also be used, the difference is only in weight.
    A stiffer foil for grilling can also be used on the bulbs themselves, it can be wound into a spiral with an overlap, to fly next.
    Letovat sa to da priamo na rure, using the common. 100W transformer solder and aluminum brazing liquid, it's good to practice on a piece of foil first.
    It is optimal for an amateur construction to use discarded Al foil from an outlet store for yogurt cups, or similarly cheap solutions.

    I created the internal lines of the leads to the dipoles from straws, which I took from the decoration in the bar. The length is approx. 1 m, but you can also use shorter straws stuck together from some fast food.
    I put these straws through several layers of expansion pads cut from the bottom of a PET bottle.
    In this way, during and after assembly, the drives will maintain the exact distance and cannot move during handling and transportation.
    Their position in relation to each other and to one bulb is very critical.

    I wound the matching transformer from the wires of,5mm of FTP/UTP cables, connected to each other and soldered together, they did not cause a significant problem.
    They formed a winding of 128 turns.
    They formed the primary winding of the transformer 3 zavity With 2.5mm wire

    The setting consisted in finding the optimal number of turns on the secondary side of the transformer.

    The range of operation was very narrow, approx. 20kHz.
    Then it was necessary to change the branch.
    Efficiency quite sufficient, even though I think, that probably a large part of the energy emitted from ant. sa absorbovala v blizkom okoli anteny.
    In the open space, it appeared roughly as an equivalent invert in a 2x 18.8m dipole suspended on a 6m pole (NVIS ant.).

    The characteristics of the EH antenna are similar to magnetic slot antennas.
    First, a narrow operating frequency, but especially with an extremely high electromagnetic field in the vicinity of the antenna.
    The most critical point is the center of the EH antenna dipole, where an extremely high VF voltage appears.
    In this place, if the insufficiently dimensioned plastic is used, a HV breakdown will occur, or matrial charring.
    The dilation should be between the spokes around 1-1,5 diameter of the circumference of the support pipe.
    As the distance increases, the decreasing capacity begins to have a negative effect “dipole” at a smaller distance there is a risk of a breakdown.

    A basic condition for a functional EH antenna, the transformation and optimal transformer pull-up by the dipole capacity of the EH antenna is suitably designed.

    Moisture and a change in the environment around the antenna are also problematic.
    If I find, I will send a photo.
    The antenna is interesting for mobile operation, when it is not possible to build a different sized antenna.
    It is more effective than an extremely shortened mobile antenna.
    For multiple bands, you need to have a different antenna for each band, or solve exchangeable transformers.
    If there is interest, I will also send pictures

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