K7TJO My first copper pipe hentenna. A 4/3 λ loop with a matching section.

   [( Paraglider Flying Weather links in BC and NW Washington )]
 ┌┬────┐
 └┴────┘
 Hentenna
Vertically
Polarized!

Click for larger image.
  • Picture of 2 meter copper pipe hentenna; K7TJO being tested on a walking stick mount.
  • overall length 40 3/4"
  • overall width 13 3/4"
  • feedpoint loop adjustable and adjusted to 8.5"od 7.9"id --> 8.2" center to center
    Note: after a couple years in the weather, the hose clamp attachment became very rusty and the performance of the antenna suffered noticeably. I cut the horizontals and replaced the hose clamps with T copper pipe fittings and it works great again. (2009)
  • Fuzzy close-up of the Hose-Clamp adjustment attachment for the matching loop.

    I made a sloppy wire one first, but I made it too small -- it's tuned to 152mhz with a fairly narrow bandwidth.

    My Versatile Online Calculator -- Inches and meters Javascript Wavelength Calculator, Wire diameter calculator for scaling your favorite design, and generic feet and inches to metric. (not just decimal feet.)

    You've heard of the J-pole, See the Ski-pole for 2 meters and 6 meters!

    (Yes, really made from ski poles.) The long one jams into the shorter one to go from 2M to 6M. The shorter one is threaded into a mag mount from a CB-antenna found in a free box at a garage sale. And No, I don't drive around with the 6 meter up, but I do with the 1/4 wave 2 meter.
    Notes about my antenna compared to the more professional one referenced below:
    1. The attachment of the two matching feed arms to the main body as seen in the picture, is a friction attachment with three parts:
      1. I used a grinder to make the end of the short tube fit nearly flush against the long tube.
      2. I drilled a hole through the pipe and fed a steel wire through it. (Rusty in the picture)
      3. I used a hose clamp fully undone and fed behind the wire then around the long tube.
    2. My guess is that the weakest part of the current configuration is actually the steel wire, which I will replace with something less easily corroded.
    3. It hasn't been soldered.. I have held it toghther with aluminum tape.
    4. There is a solid nylon "plug" inserted into the inner ends of the feedpoint.
    5. The feed-line is only taped at the moment, but it works great. I wouldn't mount it permanently like this though.
    6. I started one inch larger and cut to here. It might be even better if cut further.
    7. I envision a tent-pole style interior elastic cord to hold this all together and still allow it to be broken down to a more easily carried package.
    8. My next one will be wire again, but with kite-parts as the spreaders. I'm looking for an easy corner fitting. At the moment, arrow knocks look like the best candidate.
    9. I am also going to make a wire one for 440mhz.
    10. I'm contemplating a Reflector to increase the gain and change the bi-directional peanut pattern to uni-directional pear. I know it should be "slightly" larger, but I don't know how much. ( http://www.signalengineering.com/ultimate/cubical_quad.html says 10% increase in circumference)

    Contact: olneytj at comcast dot net or K7TJO
    Has a Scaling calculator to go from one size wire and wavelength to different sizes and wavelengths. (Linear elements only) Inches and meters Javascript Wavelength Calculator == includes provision for calculating electrical wavelength given cable type., Wire diameter calculator, and generic feet and inches to metric. (not just decimal feet.)

    If you don't see line drawings, click here
                                             ┌┬────┐
                                             └┴────┘
                                            Hentenna 
         Adjust 
     from 1/10th to        In this position, radiation is vertically polarized
     ┌─────1/6 WL───┐
     ┌───────────────────────────────────1/2 WL overall────────────────────────────────────────┐
     ┌──────────────┬───────────────────────────▄█▄────────────────────────────────────────────┐ ┐
     │  for best    │                            █  The three verticals are the radiators.     │ │
     │   SWR        │                            █  The Hentenna is a special case of a class  │ │
     │              │ Feed Point center          █  of antennas known as ADR Asymetric Double  │ │
    ═│═════════════                              █  Rectangles. See                            │1/6 wl
     │feed line out │                            █  Dan Handelsman, N2DT                       │ │
     │  of end      │                            █   QEX, Jan/Feb 2002 pp 12-22                │ │
     │              │                            █                                             │ │ 
     └-─────────────┴────────────────────────────█───────────────────────────────────────────-─┘ ┘
                                                 █
     Generalizations:  Larger diameter gives     █
     greater bandwith.  Radiation is directional █ 
     perpendicualr to the plane of the rectangle █
     A reflector of the same shape but slightly  █ Non-conducting mast -- no metal contact to loop
     larger can improve both the forward gain    █
     and the front to back ratio. If you need    █
     omnidirectional coverage, this is not  the
     best antenna, but if you can use direction, 
     this is an easy to make antenna with much less fuss 
     than many others of similar gain.  It is very wide
     bandwidth and forgiving of small differences in element 
     size.  By moving the distance of the feed vertical
     toward or away from the end of the loop, SWR 
     can be adjusted.   
     
    
                                            ┌┬────┐
                                            └┴────┘
                                            Hentenna 
         Adjust 
     from 1/10th to        In this position, radiation is vertically polarized
     ┌─────1/6 WL───┐
     ┌───────────────────────────────────1/2 WL overall───────────────────────────────────────┐
     ╔══════════════╦═══════════════════════════▄█▄═══════════════════════════════════════════╗ ┐
     ║  for best    ║                            █  The three verticals are the radiators.    ║ │
     ║   SWR        ║                            █  The Hentenna is a special case of a class ║ │
     ║              ║ Feed Point center          █  of antennas known as ADR Asymetric Double ║ │
    ═║═════════════                              █  Rectangles. See                           ║1/6 wl
     ║feed line out ║                            █   Dan Handelsman, N2DT                     ║ │
     ║  of end      ║                            █   QEX, Jan/Feb 2002pp 12-22                ║ │
     ║              ║                            █                                            ║ │
     ╚══════════════╩════════════════════════════█════════════════════════════════════════════╝ ┘
                                                 █
     Generalizations:  Larger diameter gives     █
     greater bandwith.  Radiation is directional █ 
     perpendicualr to the plane of the rectangle █
     A reflector of the same shape but slightly  █ Non-conducting mast -- no metal contact to loop
     larger can improve both the forward gain    █
     and the front to back ratio. If you need    █
     omnidirectional coverage, this is not  the
     best antenna, but if you can use direction,
     this is an easy to make antenna with much less fuss 
     than many others of similar gain. It is very wide
     bandwidth and forgiving of small differences in element 
     size.  By moving the distance of the feed vertical
     toward or away from the end of the loop, SWR 
     can be adjusted.   
    
    
    
                                            Hentenna 
         Adjust 
     from 1/10th to        In this position, radiation is vertically polarized
     +-----1/6 WL--+
     +-----------------------------------1/2 WL overall--------------------------------------+
     +-------------+----------------------------+--------------------------------------------+ +
     |  for best   |                            |  The three verticals are the radiators.    | |
     |   SWR       |                            |  The Hentenna is a special case of a class | |
     |             | Feed Point center          |  of antennas known as ADR Asymetric Double | |
    =|=============                             |   Rectangles. See                          |1/6 wl
     |feed line out|                            |  Dan Handelsman, N2DT                      | |
     |  of end     |                            |   QEX, Jan/Feb 2002 pp 12-22               | |
     |             |                            |                                            | | 
     +-------------+----------------------------+--------------------------------------------+ +
                                                |
     Generalizations:  Larger diameter gives    |
     greater bandwith.  Radiation is directional| 
     perpendicualr to the plane of the rectangle|
     A reflector of the same shape but slightly | Non-conducting mast -- no metal contact to loop
     larger can improve both the forward gain   |
     and the front to back ratio. If you need   |
     omnidirectional coverage, this is not  the
     best antenna, but if you can use direction, 
     this is an easy to make antenna with much less fuss 
     than many others of similar gain.  It is very wide
     bandwidth and forgiving of small differences in element 
     size.  By moving the distance of the feed vertical
     toward or away from the end of the loop, SWR 
     can be adjusted.   
     
    
    
    
    
    

    Hentenna links:
  • Hentenna Basic info http://homepage3.nifty.com/lzk/ANT3.html
  • Hentenna Basic info (Hentenna Revisited)
  • http://www.hamuniverse.com/2hentenna.html WA0ITP's first try
  • Picture of 2 meter copper pipe hentenna; K7TJO being tested on a walking stick mount
  • Fuzzy close-up of the Hose-Clamp adjustment attachment for the matching loop.

    Notes below From: http://www.qsl.net/wa0itp/

    WA0ITP's later recommended measurements.


    "BUILDING IT

    I [WA0ITP] recommend building the 1/2 " copper pipe Hentenna to these dimensions.

    overall length = 40 inches
    overall width = 12 3/4 inches
    feed point = 7 3/16 to center line of T connector

    You'll need one 10' piece of pipe, four right angle elbows, two tee's, and two end caps from the hardware store, total cost about $12. With the dimensions below you can just jam it all together heat and solder and it will work just fine. Or you can be a little fussier and adjust the dimensions perfectly before soldering.

    Cut the pipe as follows: (use a tubing type cutter, a hack sawĺs too awkward,unless you're really good)
    2 pieces 31 13/16" for the long side pieces above the Tee's
    2 pieces 6 1/16" for the short side pieces below the Tee's
    2 pieces 11 1/2" for the two end pieces
    2 pieces 5" for the feed points.

    Use tin/lead rosin core solder, and shine up the ends of the pipe before soldering. I just laid it out on the garage floor to keep it flat and applied the heat. Be sure to wear safety goggles since concrete may "pop off" little pieces when overheated. The caps go on the end of the feed tubes and the distance between them will be around 3/4". Solder the coax braid to one cap and the inner conductor to the other. "


    Hentenna measurments K7TJO. Calculated without any velocity factor or diameter adjustments. Wavelenght = wl = lamda = λ
    Note that some descriptions call for the width of the smaller rectangle to be 1/6 wl while others say 1/10 wl. Changing the width adjusts SWR.

    Link to excel spreadsheet that generated the table below.

    From :March 29-30, 2003 http://www.radiohc.cu/
    dxers29mar.htm

    HEN is a japanese word that means something like amazing , marvelous or even magic !!! Well the HENTENNA is a rather easy to design and build... Its construction is rather simple, and it is BI-DIRECTIONAL antenna system, with a pattern that has two broad lobes, and two sharp nulls... The HENTENNA also has GAIN over a dipole, not much, but nevertheless some gain...
    Ready to copy, here we go with the data... Just draw a rectangle... the geometrical figure with two long and two short parallel sides...
    The long sides of the rectangle that form the HENTENNA are exactly one half wavelength long...
    and the two short sides are one sixth of a wavelength long.
    So we have a rectangle that is 0.5 wavelengths on the long sides and 0.16 wavelengths on the short sides. The antenna is fed very easily, by placing the feedpoints 0.16 wavelength or 1/6 of a wavelength from one end of the long sides. Almost perfect one to one voltage standing wave ratio is achieved by just slightly moving the feedpoints up and down the long sides of the antenna. You can make a nice HENTENNA for the two meter amateur band, using solid copper wire, with no 10 or no 8 bare copper wire as the ideal ones to make the antenna.
    The construction is as easy as one can think, and the antenna requires just one well done connection to complete the rectangular loop.
    Ideally you should solder the wires to complete the loop, something you will also need to do to the coaxial cable that connects the antenna to your receiver or transceiver.
    For the two meter amateur band, the most popular ham band worldwide, the HENTENNA has long sides of 98 centimeters, and the short sides are just 32 centimeters long.
    The feedpoints are located exactly 32 centimeters from one end of the antenna, and you may need to move the feedpoints slightly up and down to achieve a perfect match.
    One easy way of holding the HENTENNA is by using a length of CPVC pipe, the one used by plumbers nowadays....
    A two meter long CPVC pipe of about one inch diameter will serve both as the support for the HENTENNA and also as a short mast.
    You can install a HENTENNA almost anywhere, and for the two meter band application don't forget to place the antenna in the direction of your favorite repeater or area of coverage.

    Continued on 5-6 april
    Now item four: A note about the HENTENNA that was pending from a recent show... The HENTENNA , when used for horizontal polarization must be installed with the long sides of it in a vertical position !!! Surprising as it may seem , that's the way to do it, and when using the HENTENNA on 2 meters FM, do remember to install it so that the long sides of the rectangle are parallel to the ground... It is something that is not so obvious, and that has caused that some builders of the HENTENNA wondered what was happening , as the antenna did not seemed to work properly ... and they thought that the antenna was not a good design... BUT, after twisting the position of the antenna all around, the found out that it works really very well !!! So , again, be aware that contrary to what you may think , the HENTENNA is used horizontally for vertical polarization, that is , you place the long sides of the HENTENNA parallel to the ground when working two meters FM that is vertically polarized !!!

    Inches and meters Javascript Wavelength Calculator, Wire diameter calculator,
    and generic feet and inches to metric. (not just decimal feet.)


    length
    widthmatching
    end loop
    major
    diagonal
    spreader
    length
    widthmatching
    end loop
    major
    diagonal
    spreader
    circum-
    frence
    circum-
    frence
    mhzλ meterλ inch1/2 λ
    inches
    1/4 λ
    inches
    1/6 λ
    inches
    1/10 λ
    inches
    inches1/2 λ cm1/4 λ cm1/6λ cm1/10 λ
    cm
    cmcmin
    144.002.0881.7540.8720.4413.628.1743.08103.8251.9134.6120.76109.44276.85109.00
    144.502.0781.4640.7320.3713.588.1542.94103.4651.7334.4920.69109.06275.89108.62
    145.002.0681.1840.5920.3013.538.1242.79103.1051.5534.3720.62108.68274.94108.25
    145.502.0580.9040.4520.2313.488.0942.64102.7551.3734.2520.55108.31274.00107.87
    146.002.0580.6340.3120.1613.448.0642.49102.4051.2034.1320.48107.94273.06107.50
    146.001.9780.6338.7019.3512.907.7440.7998.3049.1532.7719.66103.62273.06107.50
    146.502.0480.3540.1820.0913.398.0442.35102.0551.0234.0220.41107.57272.13107.14
    147.002.0380.0840.0420.0213.358.0142.21101.7050.8533.9020.34107.20271.20106.77
    147.502.0379.8139.9019.9513.307.9842.06101.3650.6833.7920.27106.84270.28106.41
    148.002.0279.5439.7719.8813.267.9541.92101.0150.5133.6720.20106.48269.37106.05
    148.502.0179.2739.6419.8213.217.9341.78100.6750.3433.5620.13106.12268.46105.69
    149.002.0179.0039.5019.7513.177.9041.64100.3450.1733.4520.07105.76267.56105.34