The 160m antenna described in my previous entry works amazingly well. I operated in the CQWW 160m Contest this weekend and was able to Work All States. In addition, I worked a number of countries including Chile, Denmark, Scotland, France, Japan, Luxembourg, Sweden, and Hungary. In total I made 343 QSO's on 160m this weekend which more than doubles my lifetime 160m QSO total of 230 QSO's!

Doing some research I've concluded this antenna is basically a half-sloper. Or maybe a low half-dipole since it's not sloping. WD8DSB made an interesting post to the Top Band Reflector in 2001 which describes some measurements he took of the feedpoint impedance. He concluded if the half-sloper is not mounted very high from the ground the feedpoint impedance would provide a reasonable match to 50 ohm feedline. I had considered raising the feedpoint up the tower but there may be little to gain and it could affect the feedpoint impedance. K6SE(SK) made a followup post stating polarization is predominately vertical with the azimuth skewed in the direction of the wire. Bottom line is IT WORKS!

8 Comments

Linear

  • Dave KE0WM  
    Alan,

    Great job on the antenna.. I am impressed. I just put up an 160 OCF, but someone once told me to load the tower.
    I pre-sume if you have a beam on the tower... this cannot be done???? Where else can I get more info on loading the tower??

    Many thanks...
    73's & God Bless,
    Dave KE0WM
    #1
    • N5NA  
      Thanks for the comment Dave. Actually I think a beam on a tower that you are loading works as a top hat and is beneficial. My tower has a Force 12 C19XR yagi and a 6 meter yagi just above that.

      The ARRL Antenna Handbook has info on loading a tower as well as ON4UN's Low Band DXing book.

      I've never seen anything in any books about the setup I used from W5AJ/W5UN so I wasn't too sure what to make of it!
      #1.1
      • Don  
        Hello Alan,

        Sure sounds like your 160 meter antenna is doing just great, and wonder if you still have it in service? The ARRL 160 meter contest is just around the corner, and this contest is always a blast.

        For possible improvement, I would suggest moving the feedpoint (mounting height) up to around the 35 foot level to get the highest current point of the antenna further from ground to help antenna efficiency (less losses) while still being able to maintain a reasonable feedpoint impedance for matching direct with 50 ohm coax. You have already stumbled across some of my test data, so no need to explain my above comments.

        73's from Wuqing China,
        Don Kirk (wd8dsb)
        #1.1.1
        • N5NA  
          Hi Don,

          Thanks for the recommendation! I'll give that a try but I'll probably just go about 22'. That's the top of the first section of my crankup so that would be easiest.

          I'm hoping to operate in the ARRL 160m. Last year I was out of town that weekend but I think we'll be here this year. Plus, I didn't have the antenna up then.

          Again, thanks for the comments!

          Alan
          #1.1.1.1
  • Petr  
    Hi all,
    please be noted that Don, WD8DSB is talking about the base loaded half sloper which means to have installed big coil in the feed point on the tower then folowed by 68' of wire sloped to ground.
    The performance will be different then standard not shortened half sloper.

    73 - Petr, OK1RP
    #2
    • Don  
      The full size half sloper will indeed provide better performance than one that uses some inductive loading. Nevertheless I tested full size half slopers as well as short half slopers (inductive loaded) and my comments about mounting height vs. feedpoint impedance apply to both shortened (inductive loaded) and full size half slopers.

      Don
      #2.1
      • Petr  
        Hi Don,

        perfect. Thank You for Your additional info. It's good to know it. I just would like to let people know that performance will be a bit difference if the base loading is used instead of full lenght half sloper even in resonable height.

        BTW: I have Your antenna installed from last weekend so I am testing it intensively on TB for now...:-) (feed point apex 10m, 15mm Cu strap in parallel with pipes goes to ground, no radials now)

        73 - Petr, OK1RP
        #2.1.1
  • Petr  
    Hi all,

    as I promised there are some experiences with the installation > short first results...

    I have this antenna installed from last weekend and I am testing it intensively on TB for now... (feed point apex 10m, 8 wounds of 1ft diammeter coax choke, 15mm Cu strap going down in parallel with vertical pipes to ground represented by 10mm Al circle rope buried about 1.5m under surface, length is abt 10m under surface along house, no radials now)

    Installation: I had to cut 6.3m to get some resonance/SWR dip.! If it's right that wire length is originaly 75 ft then my current length is around 53.5 ft...with SWR dip 1.2 to 1 on 1815kHz. I am very surprised with this length but I have no idea what happends.

    Results: 50QSOs in 1st RSGB 1.8MHz Contest last week with 100W out, I heard J38XX, VE and W5 (not worked) last weekend. My first impression is that it's doing something > need to be more tested.

    Ideas appreciated.

    73 - Petr, OK1RP
    #3

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