Online Today
and NO the Luftwaffe didn't think of this one, Hi Hi...
All of the designs were conceived in K6STI's YO7 Professional software and scrutinized in 4nec2. They stand up to examination in any software package so .ANT and .nec files are included for this purpose. You can use for example AO (K6STI's Antenna Optimiser) or 4nec2 or Nec2Go which open the .ANT files directly. Thanks to Arie Voors and Pat W0OPW for making this possible.
A simple split dipole is all that is required as the driven element. Use a balun if you so wish or better still a suitable ferrite slipped over the feeder close up to the feedpoint, see KB8RQ direct feed arrangement. However, the G4CQM 50Ω coaxial dipole provides an alternative and effective solution!
ALL DIMENSIONS ARE FREE-SPACE SO ELEMENTS NEED TO BE INSULATED FROM AND RAISED SUFFICIENTLY HIGH ABOVE THE BOOM TO AVOID BOOM CORRECTION!
December 2011... I've had this idea in my head for some time of using unconventional parasitic element spacing as a means of manipulating a yagis characteristics. The problem is that software optimisers tend to move elements into conventional positions. However, after several attempts I've managed to overcome the obstacles and deliver amazing performance as seen in the 2M Band (144MHz) CQM12UX, CQM8UC2 and 6M Band (50MHz) 6CQM12UX yagi beam antenna designs and with exceptional F/R (Front to Rear power ratio) in the H-Plane. This plane is usually the most difficult to clean up so all of my development work is done in the H-Plane alone, if you do this the E-Plane comes right anyway as I discovered! I've called this new innovation the FLAT LINE OWA or FLOWA as all the characteristics (F/R, GAIN, VSWR and Z) are virtually flat lines when plotted or can be altered as required.
The CQM8UC2 covers 144 - 146MHz with a VSWR below 1.1:1 across the entire range!
30-12-2011... I soon realised I'm on to something VERY BIG with the FLOWA concept, here is further proof, the CQM12UX and 6CQM12UX pattern is incredible and holds over the entire operational bandwidth, better than anything seen before, period!!!
Compare a well known competitors conventional OWA beam (red line) which is 661mm longer than the CQM8UC. Vertical and Horizontal planes seen below. Forward facing 1st sidelobes are irrelevant particularly for EME contacts, it's the rear bubble that counts and the CQM8UC actually has the better F/B figure note! Not much difference in forward gain about 0.4dB...
Run your pointer over the VSWR plot below and compare the well known competitors conventional OWA beam which is 661mm longer than the CQM8UC, note that the VSWR worsens with the competitors beam...
Run your pointer over the elements table below and compare the well known competitors conventional OWA beam which is 661mm longer than the CQM8UC. Analysis of both antennas is in the H-Plane. Note that to achieve a better F/R the competitor beam has had to sacrifice gain hence the Gain Figure-of-Merit is way down at -0.6dB NEC-2 :-(
REMEMBER TO DOUBLE (X2) ELEMENT LENGTHS SHOWN ABOVE AS YO7 ONLY SHOWS HALF LENGTH!
G4CQM's PowAbeam Professional Yagis by Derek Hilleard G4CQM - This website and contents are protected by international copyright law: Copyright © Derek Hilleard G4CQM 2011 All Rights Reserved
Email: derek.hilleard(at)g4cqm.co.uk
These yagi antenna designs are intended for commercial application and as such require a licence to be granted prior to commencement of production. Private experimenters are free to use these designs for their own personal enlightenment. However, no guarantee or warranty is offered or implied.