Hex Beam by K4KIO
Site publication date
12/2007
FAQ's

1. Why should I be considering a broad band hex beam?
Because it performs better than the classic hex beam. And on top of
that it is easier to build and easier to adjust. The only drawback is that
it is slightly larger in diameter by less than three feet.

2. Are the wire lengths critical?
A. Well, if you change the wire length for the reflector on 10M by one
inch, it changes the design frequency by about  130 kHz. Two inches
would be about 260 kHz, and so on. You can do a simple ratio of
frequencies to figure the change in wire lengths.

    Change in wire length(+,-) =  Change in frequency(-,+) X Orig. wire
    length / Original frequency

(Remember, increasing frequency requires decreasing wire length and vice
versa.)

If you change the reflector lengths be sure and do the same for the
driver wires.

3. How important are the tip spaces?
A. They affect the front/back performance and the SWR. But they are not
as critical as on the classic hex beam and are easier to adjust
because you have only two adjustments per band rather than four.

4. What if I want to use a different gauge of wire than 16 gauge?
A. That is fine. Just use the Conversion Table on this page to scale the
driver wire lengths shown here for your particular wire thickness. The
reflector wire gauge is relatively immune to differences in wire
thickness so just use the table amounts for 16 gauge. Also, leave the
end spaces as they are shown here.

5. How high should the hex beam be?
A. Higher is better for DX generally as it reduces the takeoff angle of
the main RF lobe. However, the hex beam can be quite effective even
at modest heights.

6. What about use of steel wire or aluminum instead of copper?
A. You will need new dimensions based on conductivity of those
materials. The dimensions here are strictly for copper.

7. What about stranded wire or solid wire?
A. Either is fine.

8. What about insulated wire?
A. It can probably be used but you can't depend on these specifications
which are based on bare copper wire.

9. How important is spacing on the center post?
A. Post spacing is mainly determined by the geometry of your particular
hex beam. Try to get your wires generally parallel, level with the
ground, symmetrical, etc. Spacing can become a problem if they are
too close. In particular, it has been found by some that if the 10 meter
wires are too close to the 12 meter wires, the two bands can interact
with each other. If you can't get the specified 4 inch spacing between
12 and 10 meters while keeping the 10 meter wires parallel, that's OK;
just pull the wires down the post a bit; performance will be better.

10. Should I feed the hex beam at the top or the bottom?
A. Top feeding will provide better results overall.  

11. Should I connect the bands with wire or coax?
A. Coax will provide better results. Use 50 ohm coax.

12. Do I need a balun?
A. It is a good idea because it prevents surface currents flowing on the
exterior of the coax and thereby distorting the radiation pattern.

13. Where can I learn more about the hex beam theory?
A. Visit the web site of Steve, G3TXQ.
Specifications and FAQ's
Lengths of wire elements and spacing
Note that driven element consists of two 1/2 sections and
reflector consists of one section

Units are Inches, wire is 16 Ga (0.051 in. dia.)
ddddd G3TXQ Broad Band Hex Beam Spec.
                                                                             Ht. of wires
dddddddDesignd1/2 Driver   Full Reflector   Tip     above the
ddBand   Freq.   wire length    wire length  Space   Base plate
ddd20    14.150     218.0            412.0          24.0        42
ddd17    18.100     169.5            321.0          18.5        20
ddd15    21.250     144.5            274.4          16.0        14
ddd12    24.950     121.7            232.0          13.5        10
ddd10    28.400     106.8            204.4          12.0          6
Conversion Table for Different
Wire Thickness
These factors can be used to calculate new
wire lengths if wire that is not 16 gauge is
used
Overall data on the G3TXQ Broad Band Hex beam by K4KIO

Freq. bands (M)                                 10, 12,15,17,20
Weight                                                22 lbs
Diameter                                             22 ft
Wind Surface Area                              under 6 Sq Ft
K factor                                               242 ft lbs
Building the G3TXQ Broad Band Hex Beam
Conversion table for driver wires only; use 16 ga.   
               table for reflector wires.

Wire Dia. (In.)   Wire Gauge    Multiply lengths by

dddd0.032                20                        0.996

dddd0.040                18                        0.998

dddd0.051                16                        1.000

dddd0.064                14                        1.002

ddd  0.081                12                        1.004

dddd0.102                10                        1.006