The HW-42HP is an Off Centre Fed Dipole with a difference. Designed to operate on all bands from 40m (7MHz) - 6m (50MHz). It will operate on 40, 30, 20, 17, 15, 12 and 10m without an ATU (SWR <3) plus 6m with an ATU. It is also possible to operate on both 80m (3.5MHz) and 60m (5MHz) via a good ATU. This will handle 400W key down or 500W PEP.
Having a feedpoint 1/3 of the way along gives a feedpoint impedance of 200ohms. This is not ideal for modern day transceivers requiring an antenna with a 50ohm impedance. Therefore, a 4:1 balun is added at the feedpoint to alter the impedance to something closer to the 50ohms required. This then allows the antenna to be fed using standard 50ohm coaxial cable such as RG8 or RG213.
The overall length of the antenna is 20.28m or 66ft. It may be mounted horizontally, as a sloper or as an inverted vee. If space is at a premium it may also be 'bent' to fit in with no loss in performance.
This is now Mk. VI following recent updates to the original.
See the excellent review by Steve Nicholls, G0KYA in the July 2014 issue of Radcom.