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QRP Portable - with a small profile antenna

Discussion in 'QRP Corner' started by N1KTJ, Apr 25, 2016.

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  1. N1KTJ

    N1KTJ Ham Member QRZ Page

    Would like to break out of the typical QRP Portable discussion and try to get feedback on portable small profile antennas than can be worked. Maybe hand in a zig-zag configuration on a wall or ceiling. or an inverted L on a wall to ceiling in an apartment. Does anyone have good reference material on small profile antennas?

    given that a typical bedroom will have seven foot ceilings and maybe ten to 15 foot square space on that ceiling. Any real word test results do that?
     
  2. N1KTJ

    N1KTJ Ham Member QRZ Page

  3. K4YND

    K4YND Ham Member QRZ Page

    That will be tough. I believe a random wire out the window into a tree will out do just about anything inside. Wire outside might not be possible, so I too would be interested in what is used
     
    KD5CQ likes this.
  4. VK3YE

    VK3YE Ham Member QRZ Page

    I discuss many of the possibilities here: http://home.alphalink.com.au/~parkerp/gateway/noapr99.htm

    If you can fit in a half wave dipole, even if it contains loading that is likely to be the most efficient you can get.

    End capacitive loading (ie wires at right angles to the radiator) is more efficient than inductive loading though both can be used on the one antenna.

    I've had good results with this magnetic loop for pedestrian mobile use (but would also work indoors provided you're not in a concrete/metal building) http://home.alphalink.com.au/~parkerp/projects/projmal.htm

    Moxon's book 'HF Antennas for all locations' is worth buying.
     
  5. N1KTJ

    N1KTJ Ham Member QRZ Page

    many windows are sealed with a screen that can only be serviced by your landlord. so nothing going out through that. and my attic has the air conditioning and heating duct work there. A box with windows. But I do cheat via a small hole in the screen to drop a coax down and out to my parked car with an antenna; but cheating is getting irritating.
     
  6. K8JD

    K8JD Ham Member QRZ Page

    QRP, Its All In The Antenna !
    My opinion is : the smallest (power) radios need the BIGGEST antennas !

    My best example is my experience at a field day a few years ago.

    A group had a QRP setup at field day, When I arrived they were sitting there , calling CQ and griping they were not getting any answers ... They had a nice little QRP rig, an autotuner, and a small antenna in a tripod. maybe 8 or ten ft tall.
    They tried 20 and 40M with no results, using a Tuner that showed, bypassed, SWR was over 3:1.

    Nobody thought of trying to adjust the antenna.

    The owner of the antenna had set it up and left the site. Some of the pieces and the user's manual were not there.

    My solution was to run to my car and get some wire, rope, and coax. I then measured out two 33 ft chunks of wire, fasened to the coax end with crimp splices and tosed the ends into a tree and pulled up the dipole, connected the coax, bypassed the tuner, and got them on the air ! Making and erecting the antenna took me about 15 minutes.
    40M CW QSOs started coming as fast as they could log them.

    (all the time I was doing this job, the ops just sat and watched me and commented that some scrap wire could not possibly work, while that 400 dollar, wonder, mini-antenna could not) .
     
    Last edited: Apr 26, 2016
    AI6KX, KC8VWM, G8NVX and 6 others like this.
  7. KU3X

    KU3X Ham Member QRZ Page

  8. VK3YE

    VK3YE Ham Member QRZ Page

    Agree with K8JD. It's hard to build an antenna appreciably better than a dipole but very easy to build one that falls short.

    A dipole with tuned feeders can do several bands quite efficiently, as shown in this video:

     
    KC8YLT likes this.
  9. KF5FEI

    KF5FEI Ham Member QRZ Page

    Distributed capacitance antenna?
     
  10. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    I have a random loop around the perimeter of the ceiling of my third floor room, with a 4:1 current balun.
     

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