![]() |
The K6STI Receiving Loop![]() This relatively unknown antenna does an amazing job pulling weak low band signals out of man-made noise backgrounds |
![]() |
![]() Low band operators who have already used Beverage antennas are nearly always disappointed with the K6STI loop. Beverages will 'spoil' you for any other low noise receive antennas, but many hams do not have room for them. If you want to reduce atmospheric noise and you do have some room for Beverages or phased verticals, both of which are directive, then those antennas would be a much better choice. Likewise, the WA2WVL cardoid loop array provides good directivity over a narrow bandwidth if you have the room- about 80 feet on 80 meters. (QST, August 1993, p.31) The Ewe, K9AY, and Flag and Pennant antennas also provide good directivity in a fairly small space, but with lower receive signal levels. They might benefit from the use of a receive preamp, and so might the STI loop, to a lesser degree. (I do not use a preamp with mine, however). It is a good idea to add a highly selective tuning network ahead of any preamp to avoid receiver front-end overload. This loop has an omnidirectional pattern and, in theory, it should provide no improvement in S/N for atmospheric noise. K6STI and W6KUT, who built the first loop, noticed an apparent improvement of 1 to 2 S-units even when there was no detectable power line noise present. I have also seen this behavior in my antenna. STI reasons that in populated areas the noise background may consist of many individual man-made noise sources which, in composite, are characterless. Anyone interested in this antenna is encouraged to get hold of the QST article and carefully read and reread it for full understanding. Topband operators might want to consider building a double size loop around 50 feet (15m) on a side if it will be used only on 160m. Matching network component values would have to be adjusted accordingly. Because I do not have room for low band Beverages, the K6STI loop has proven to be a most valuable low noise receive antenna for me. (Revised and updated 8 Apr 2000) (Second update 13 Feb 2002) W7LR tried a 50ft version of this antenna on 160m. He used a "pre-war" Terman handbook (p. 52) to determine that the loop inductance on 160m is about 110uH. He calculated the resonating capacitance at 1830KHz to be 60pF. His transformer was 4 turns, antenna side, and 20 turns for 50 ohm impedance coax. The core was an FB77-1024 ferrite bead. He said it "tuned nicely" (actual resonating capacitance was close to the predicted value). There were no comments as to the actual antenna performance, only that he has tried a lot more receiving antennas since this September 1995 design. |
Send Comments to K3KY | The Low Bands | PREV |
HOME | K3KY's DX Toolbar | NEXT |
|