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Does anyone here have experience with mag Loops?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by G4SEB, Sep 6, 2020.

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  1. N8TGQ

    N8TGQ Ham Member QRZ Page

    antenna01.jpg


    This is my all-band end-fed halfwave antenna. Matcher is from QRPGuys and cost $25 US. The matcher also has a basic tuner and SWR indicator. The 65' wire will tune up on 40, 20, 15 and 10 meters. If your bedroom is on the second floor, you may not even need a mast. Just use as a sloper to something at the far end.
    I got a 5 meter telescoping fishing pole from Walmart for less than $10 US. Check your local discount stores.

    Have fun!
     
  2. AK5B

    AK5B Ham Member QRZ Page

    Hi Sebastian; Yes, portable should yield far better results for you; just scout out different possibilities as far away from man-made noise sources for starters. as an RF-quiet location is ideal (part of the reason I love operating portable by the sea, it is so quiet and devoid of hash there).

    OK, so you confirmed our suspicions; you are using a 40m dipole on 20 meters! Please tell us how you are matching that high impedance and why you did so in the first place. An ordinary 20m dipole is half the length and is far easier to match in the first place.

    By the way, for a good portable antenna for 20m, why not try an elevated Marconi like I use? All you need is a telescoping glass-fibre fishing pole (@6-7m tall) and three pieces of wire about 5 meters long connected to an SO-239 panel mount. Add a short metal rod or stake you can push into the ground to slip the pole over, stretch out your two radials on either side (affix them to nearby bushes or low tree limbs, etc.), hook up your coax and you have a very good radiator for 20m dx. Here's what I do at my island/p QTH: (click on image for larger version)
    IMG_8063QRZ.jpg
    Length of PVC pipe over a weighted steel soil tamper for my pole to slip into; this was later painted flat grey since I tend towards stealth for every antenna installation (never hurts).

    IMG_8070QRZ.jpg
    17/20m transportable fan vertical put together in my back yard (6m hexbeam on another mast on right)

    IMG_8119QRZ.jpg Fully set up with radials elevated by orange driveway markers and tripods; the wind is so strong here I use one of the palms to support my antenna from blowing over (you can see the top poking through above it). The stone bench was already there so I chose this spot for ease of operation; setup and breakdown takes about twenty minutes. Photo was taken at dusk and everything was about to be disassembled for transport the 3 miles back home.

    Operating portable enhances all of one's contacts, too---I'm convinced. It is so much fun talking to people far, far away out in the fresh air!

    So do consider a vertical for 20 meters; the height and footprint of one is fairly compact and manageable.

    As for the high voltages and dangers associated with STLs---they're also just as present in many other antennas---even the ends of radials and dipoles carry high voltages and potential harm. Practice safe utilization with every antenna and use common sense. Never touch an antenna while tuning up or transmitting, of course, and create regular set-up and take-down procedures; everything goes a lot smoother in the long run.

    Too bad you can't use that church spire for operating but now you will have the fun of scouting out other good portable locations close to home instead. Consider this; you might get lucky and find an empty field or forest with tall trees out of the way where you could erect a stealthy wire and feedline to leave in place---always at the ready for convenient field ops. Food for thought, at any rate.

    73,

    Jeff
     
    K6CLS likes this.
  3. AC7AZ

    AC7AZ Ham Member QRZ Page

    I had great results with this 40 meter magloop. At 6 feet it would outperform my 40 meter dipole at 40 feet.
    Narrow as can be, but an awesome antenna.
    1-7/8” diameter copper pipe, gamma match feed.
    I ran 800 watts through it daily on 7.195 years ago.
    [​IMG]
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    KX4O, NQ8J, KD9PQB and 2 others like this.
  4. AF7ON

    AF7ON Ham Member QRZ Page

    You can get a match with both horizontal and sloping radials - I have tried both, and some adjustment of the vertical length may be needed, but it isn't a lot. For a portable antenna, I use a 12 meter (40') Spiderpole and wire element with the feed-point about halfway up, a short whip on top to extend it from around 21' to 23' to adjust the vertical length and four 8' 6' radials run at about 45 degrees along the guy wires. Works well and the match is very close to 50 ohms.

    Mike
     
    AK5B likes this.
  5. N8TGQ

    N8TGQ Ham Member QRZ Page

    Heres an idea thats easy, cheap and can be reversed if it doesnt work:

    Wind up both sides of your full wave dipole until they are each 5m long or total of 10m for the whole thing.

    Then fine tune using your nanovna by winding wire in or out a bit.

    Then see if you get better results.

    http://www.w5dxp.com/owt3.htm
     
    AK5B likes this.

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