Tällainen viesti oli Flag- ja Pennant-listalla. Onko KAZilla kokeiltu syöttöä keskeltä ja releellä vaihdettavaa vastusta?
I wondered what the K6SE delta pennant would look like if it were fed at the center of the bottom leg instead of at one corner. The idea was to see whether it would be possible to put a resistor in both bottom corners and short one or the other with relays to switch receive directions. It turns out that, at least according to EZNEC, this should be possible. I had to increase the resistor(s) to about 1600 ohms from the 950 ohms specified by K6SE, and the "gain" suffers by about 3db (-38 dbi versus -35 dbi). Otherwise this modified version would seem to give results very similar to the K6SE design except with the ability to easily switch directions. EZNEC says both should have roughly 32db front-to-back. The feedpoint impedance for the switched version was about 1200 ohms per the model. As several topbanders have pointed out, the pennant basically gives a cardioid pattern with a decent null in one direction but without very much front-to-side rejection. It won't stack up well against a beverage or two, but if anyone with space limitations wants to try this out I'd be willing to pass along the EZNEC plots. My apologies if this is an old idea already described elsewhere David Gilbert<[EMAIL PROTECTED]> ___________________________________________________________________________________ Ennakkotilaa WRTH 2006 nyt: http://www.amazon.com/exec/obidos/ASIN/0823059367/hardcoredxcom/ ----------------------------------------------------------------- DX mailing list [email protected] http://arizona.hard-core-dx.com/mailman/listinfo/dx _______________________________________________ THE INFORMATION IN THIS ARTICLE IS FREE. It may be copied, distributed and/or modified under the conditions set down in the Design Science License published by Michael Stutz at http://dsl.org/copyleft/dsl.txt
