USING THE 3 ELE STEPPIR ON 70 MHZ....

I used my own 3 ele (at GW3YDX) for a few contacts around the UK, from a poor VHF site, and it is capable of over 100 miles QSO's as it comes out of the box, with the driven element simply being shortened until a reasonable SWR on 4m is indicated. I did not trim the parasitic elements as I believe they are too far away from the driven element to have any significant effect.

Jim Thomas at the factory has done some modelling and he suggests optimisation by the use of additional alloy tubing parasitic elements.

Suggested element lengths follow. This makes it into a 5 el on 70 MHz. I have fitted the additional elements Jim suggests to my 3 el and they give a much better match and sharper pattern. The 6m passive element is still retained, and I have also had some contacts on 2m FM out to about 50 miles away. This makes the 3 el SteppIR a very nice 8-band beam! With the addition of the 30/40m dipole, I would have a 10-band beam with one single feedline - wow!!!

Antenna 1 -  Good gain/good F/R

Gain 10.66 dbi, F/R 24 db

                      Spacing     Length

                      from ref   (1/2 ele)

New Ref            80.1"    41.6"

SteppIR Driven 102.5" 38.03"

New D1           112.4" 37.24"

New D2            151.6" 38.13"

SteppIR Director D3 192" 37.85"

Antenna 2  - High gain/low F/R

Gain 10.98 dbi element element, F/R 9.5 db

                      Spacing     Length

                     from ref    (1/2 ele)

New Ref                80.1" 41.41"

SteppIR Driven    102.5" 37.32"

New D1              110.92" 38.62"

New D2              147.52" 38.31"

SteppIR Director D3 192" 38.83"

All of the aluminum element lengths are correct if 3/8" tubing is

used. The SteppIR elements need to be shortened by 2.2% from the listed

values shown above. After mounting the aluminum elements and setting the

SteppIR elements to the right length adjust the driven element, only for

best match. It should be very close to 1:1 or something is wrong