The TZ-RD-2w is a rotary dipole antenna designed to permit operation on the 12/17m WARC 79 amateur bands. As standard the antenna is designed for the 2 main HF WARC bands. If you're new to the HF bands and want to try a bit of DX why not experiment with this antenna first. The big saving in time, effort and money to put up a full size HF antenna may be justified by getting onto the HF bands a lot faster.
The antenna is full size on 12m and therefore has effectively 0 dBd gain on that band. Since trap loading is significantly along each element losses are minimised on 17m and approximately 0.25 - 0.35dB reduction in gain over a full size 17m dipole can be anticipated. During real DX and local QSO conditions, the difference between this antenna and a full size mono-band antenna is almost negligible on 15m and would likely be materially no different on 20m expect under the most trying QSO conditions.
Given the antenna is significantly lighter and smaller than a beam or full sized 20m antenna, it is possible that the antenna can be mounted higher than otherwise might be the case and as such may result in better performance than what might have been achieved with a full sized antenna at a lower height.
BLOCK SIZE & MOUNTING CONSIDERATIONS
This antenna is ideal for the amateur without much room, or dollars, or who has an XYL not keen on a big antenna and tower in the back yard. The antenna is easily accommodated by typical "scaffolding tube" aluminum or water pipe (galvanised steel tubing). If a small concentric mast is constructed and attached to the house or dwelling a simple "pipe" mast can have your TZ-RD-2w up and in the clear for under a few hundred dollars. These types of masts can usually be extended to 10 or 12m if only a small antenna is mounted at the top, giving very good DX performance. This can be a huge saving on a tower worth upwards of $5000.00, rotator, permits, town planning, etc. You'll be surprised at how well such a simple antenna can work, if mounted in the clear at height.
Many amateurs without much room consider vertical antennas as their only alternative, however with a turning radius of only 3.25m the TZ-RD-2w offers significant performance improvements over a 10/15/20m vertical when installed at heights of no more than 8m. This antenna will provide excellent DX performance to cost ratio and can be installed in all but the smallest of inner city blocks.
The TZ-RD-2w should be mounted at least 8m above the ground. Most regulations in Australia permit a mast to be erected 3m above the tallest point of the building (primarily intended for TV antennas) but this ruling can effectively be used to get your ham antenna up at least 8m.
PORTABLE OR FIELD OPERATIONS AND DX-PEDITIONS
The TZ-RD-2w is also a fantastic antenna for portable operation. A simple aluminum mast with 3m long sleeving sections can easily be erected with some small tent pegs, half size star pickets and nylon rope guys. This will get you quickly onto the bands with a good signal. Great for a mini dxpedition to an IOTA island. A version of this antenna can be ordered with components no more than 1.0m long for easy shipment via air or vehicle.
ANTENNA DESIGN AND COMPONENTS
The TZ-RD-2w uses 2 coaxial traps which are not affected by rain since the traps are sealed. Acetal plastic insulating sections are used for mechanical strength and stiffness so that the antenna is subject to minimal sag. The centre sections of the antenna are 32mm O.D, tapering down to 12mm O.D. at the tips.
Stainless steel fasteners are used throughout as well as aluminium rivets for reduced corrosion. Three (3) stainless steel hose clamps are used to permit adjustment of the antenna on each band. Assembly is simple and straightforward, and if by chance something does go wrong most parts can be obtained from your local hardware store, e.g. nuts, crews, rivets, U bolts etc.
The Rippletech TZ-1840 balun is recommended for feeding the antenna with low loss across the bands.
The TZ-RD-2w is supplied with all stainless steel hardware except for the boom/pole mount U bolts (optionally S/S).