new HF antenna HB9ABX RoomCap Pagina 1 NEW HF ANTENNA (HB9ABX) RoomCap Antenna Felix Meyer 26th July 2005 (translation 7th.Aug 05) / update: June 14, 2009 There are the last updates available for the construction guide. Date of update = August 8th, 2008 >>> Read details here c A new, revolutionary idea allows the construction of small HF antennas, which provide the same efficiency as large antennas. Example: tested by Military + SUPER DX results on 80m + 160m DX Antenna > Information to order the construction guide: HERE
When I built the antenna myself and deployed for the first time, it was mounted only 7m above the ground. At that height, the antenna on the 20 meter band performed just as well in terms of transmission as my 13m long full-size 5/8 vertical. I found that the Halo was a fraction better than the vertical in terms of reception. Later I raised the Halo to 12m. At that height it outperformed the vertical by at least one to two S-points. The bandwidth of the Halo is a little better than the Cobweb(b). On the 20 meter band, the SWR over 250 kHz remains below 2:1. At 10 meters I measured the bandwidth over 400 kHz.
The Square Halo antenna for 10 and 20 meters is not available in any store. You have the option to purchase a Cobwebb, levae out 12, 15 and 17 meter band and adjust the radiators to the Halo principle. But building (partly) yourself is actually quite easy, costs half of a new Cobwebb and is also fun to do.
The feed point should be mounted approximately 100cm from the point where the spreaders intersect. The aluminum tube with which the antenna is attached to the mast is made for this. You can attach the dipole center or box containing the common mode choke at the very end of that tube with two sturdy cable ties.
The special thing about this antenna is that it is easy to expand to more bands. That is especially useful if you are restricted to certain HF bands due to your license. Once your upgrade your licence, you can add 12, 15 and 17 meter band dipoles. I have expanded my Square Halo with these three additional bands. The tuning takes the utmost of your patience, but once it is done, you have an easy to use five band antenna. Otherwise there is also a different approach to tuning it. 2b1af7f3a8