The antenna driven element also has to be capacitive. The ideal Z for a hairpin match is 25 - j25. A good tutorial is given starting on page 26-11 of the 20th edition of the ARRL Antenna Handbook. Hardy N7RT
----- Original Message ----- From: "John Tait" <[email protected]> To: "Kenneth Silverman" <[email protected]> Cc: <[email protected]>; <[email protected]>; <[email protected]> Sent: Thursday, August 11, 2011 4:17 AM Subject: Re: Topband: MA160V SWR/match > On 10/08/2011 21:04, Kenneth Silverman wrote: >> <SNIP> You could also try 10 or 12 turns of #12 or 14 gauge wire, 2" >> diam >> across the feed point and ground. >> Spread/compress the turns to get the lowest SWR/best match. >> >> Just to be specific: this "hairpin" match only works if the antenna >> feedpoint impedance is lower than 50 ohms, The hairpin is an >> up-tranformer >> of impedance (low to high transformation) and thus works for typical >> short >> verticals which often have very low impedances. > > If it improves your match, you also gain the advantage of having the > vertical grounded..thus giving you less static and noise to contend with > on receive. > Good luck, es vy 73 > John EI7BA > > >> If the ground system is >> poor and the feedpoint happens to be above 50 ohms (indicating a lot of >> ground loss), the hairpin will further increase the impedance and make >> the >> SWR worse. >> >> Kenny K2KW > > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
