VU2ASH home brew Broad band ,4 band Hex Beam 5/12/09
Ashok VU2ASH shack.5th dec.2009
Broad Band Hex Beam
Since I shifted my working QTH to Ludhiana, Punjab, in 1996, I was looking for a suitable antenna for my hamming. A Multiband antenna with good Front to Back ratio, moderate gain, light weight , easy to construct and preferably full size elements to avoid critical traps and complicated matching systems, in fact every hams dream !!
In Oct 2008 while searching on net I came across this multiband Hex Beam by Steve G3TXQ and instantly got hooked up. He has developed two designs Classic, which has a narrow bandwidth and Broad band version, which has almost flat SWR throughout the band.
The BB Hex beam basically consists of:-
- Two full size wire elements, a dipole radiator and a reflector for each band i.e., 14 -18-21-24 and 28 Mhz. All mounted horizontally and properly spaced to avoid any interaction, on a common insulated pipe or pole structure.
- A centralized common feed to all band elements directly from single 50 ohm co axial cable without any matching stub or system.
- Whole structure is like an inverted umbrella with minimum wind restricting area (less than 6 sq feet) perfectly balanced, stable and light weight, about 4-5 kgs depending on the pipes you use.
- Requires 11 feet rotating radius only, 22 feet of clear space! Can be easily mounted on low cost TV rotator.
- For the performance specifications the antenna has
- Front to Back ratio comparable to a 3 element yagi.
- Forward gain comparable to a 2 element full size yagi.
- SWR 1:1-1.3 flat on full bandwidth.
- Excellent reports on air.
- Low angle radiation, suitable for DX.
- And lastly, Affordable to our pockets, my total cost was antenna -4.5 K + Rotator -3.5 K.
The basic configuration of G3TXQ BB Hex Beam, the M shape is Dipole Radiator at the top and bottom C shape is the Reflector.
There are various construction articles written on this well established antenna. You can choose any form of construction suitable for your availability. Below are the links to these articles please go through them to understand construction details.
Have a look at these few…
You need to be wary of the wire-dimension data published on ON7RU’s web site. The dimensions apply to **bare copper** wire, even though he shows his beam being built with insulated wire. Unsurprisingly he then finds the tuning is low and has to make major changes to wire lengths.
If you are building with bare copper wire use the dimensions from G3TXQ web site or Leo’s – they are the same. If you are using insulated wire use the modified dimensions shown on Leo’s site.
You can also try building BB hex for 40 m, if space permits at your end, many did
It is not a big deal as the antenna is not much bigger than a 3 element 3band yagi.
Profen designs can be found here:
I have enclosed a photo of my constructed antenna. Following is the list of materials and comments
- The base plate was made from 4 mm thick Aluminum plate 14 by 14 inches. Try to use at least 4mm thick plate ,do not use thinner plate as it will get deformed .The plate can be procured from your local engineering metal shop .Mark the center and positions of all holes for the clamps after the six center lines of the spreader pipes (supporting poles )are marked. For clamping the spreaders I used 1 inch galvanized heavy duty conduit pipe c clamps available at any electrical shop. Use two clamps per spreader.
- For mounting top central feed 1 inch pipe and bottom 1 inch mast I used 1 inch threaded ms galvanized four hole flanges. These flanges are available at plumbers shop. Use at least 6 mm thick collar flange normally used for steam line or heavy fittings. Both are mounted at the center and on opposite side of the base plate.
- For spreader the best material is fiber glass pipes. Do not use PVC conduit or water pipes, they don’t last!! Each spreader is 140 inches long. You require SIX of them. The construction recommended by Leo is given below. HOWEVER you may not get these sizes easily. As such I procured the standard available sizes in India as
- Six pcs of 21 mm by 17mm fiber glass pipes 2 meter long each.
- Six pcs of 16 mm by 10 mm fiber glass pipe 2 meters long each. The 16 mm OD pipe is inserted in to 21 mm OD pipe and clamped to make total length of 140 inches for each spreader.
- The central feed support 25 mm OD by 19 mm fiber glass pipe 2 meter long one pc.
- This is the only costly material of the antenna. About 3 k. You can get these pipes specially ordered from engineering material supply store. They are being manufactured in India at several places.
- Another specific requirement is the cavler cord which is used for supporting the structure. This cord should be non stretchable under tension. You can get good quality 3/16 inch Dacron rope and pre stress it before using. Do not use cotton or pvc cord.
- The dimensions and other construction details are detailed in the links given above
- Tuning is straight forward If you have kept the spacing between elements and sizes correctly, you will have correct SWR.
- It is recommended that this antenna performs best with the height. But a height of 40 to 45 feet above GROUND level gives quite good results.
- So friends try it and let me hear your loud signals.
73s and all the best.