Guy--(and others who may contribute) I have been following your posts, and have some questions, brought on by a view at the W0UCE diagrams, at: http://www.w0uce.net/K2AVantennas.html The top figure seems to match what I understood from your post, but the figure that includes the Inv "L" confuses me, particularly with regard to the connections. I need a more simplistic description, including the connections to the transformer Thanks- Bill--W4BSG
----- Original Message ----- From: "Guy Olinger K2AV" <[email protected]> To: "Jim Miller Waco Texas WB5OXQ" <[email protected]> Cc: <[email protected]> Sent: Wednesday, December 07, 2011 7:57 PM Subject: Re: Topband: Best small space antennas > Note: the following is not a theoretical or untested antenna. There > are working antennas in the field using the folded counterpoise > described below, scoring well in contests**, in use up to a year and > more. Contest scores of the sort attained are not made using antennas > with significant deficiencies or fundamental flaws. > > A miscellaneous end-fed inverted L or end-fed inverted U over an > elevated 5/16 wave single wire folded counterpoise (FCP) will have > good radiation from a small lot, with the ability to put out a strong > signal not usually associated with small lots. In the simple > implementation of this antenna (160 only), the length of the L or U is > adjusted for zero reactance, usually resulting in a 50-60 ohm feed Z > at resonance. > > There are NO radials. The main design point of the antenna is to > minimize lossy currents induced in the dirt and confine TX signal > current to the FCP and the radiating wire. This is a real, and lossy > issue for a few short or miscellaneous radials. Enough of an issue to > kill 15 dB. > > The radiating wire first goes up as much vertical as you can manage, > then out as far as manageable, and then down if length is still needed > to prune to resonance. The main point is to pick a feed point on the > property that has your best vertical rise and then get the rest of the > length for resonance however you can. For some properties this has > meant putting extra angles in the up+over+down radiator. Some > properties will not need the "down" part. > > The antenna uses a REQUIRED isolation transformer at the feed point > because the counterpoise is NOT resonant, and the feed would really > rather use the much lower Z but hugely lossy coax shield current as a > counterpoise. The folds in the FCP are designed to maximally reduce > counterpoise fields at the ground, reducing lossy currents in the > dirt. > > The isolation transformer's leftover inductive reactance, a > disadvantage in many applications, in this case helps to tune out the > capacitive reactance of the FCP and reduces the length of the > radiating wire needed to achieve simple resonance for the antenna. > > The counterpoise extends plus and minus 33 feet from the feed point, > 167 feet folded into 66 linear feet occupied on the property. The > middle 20 feet of the 66 should be straight, but either end can be > bent away from the straight line to accommodate the property. Up 8 > feet or higher is recommended. Lowering the counterpoise increases > the coupling to dirt, increasing losses. > > The isolation transformer uses the same physical components as a > balun, but the unlike the balun there is NO connection of any kind > between the primary and secondary windings. This is accomplished with > twenty bifilar turns of double polyimide insulated #14 with teflon > sleeving wound on an Amidon T300A-2 #2 material powdered iron toroid. > One wire is the primary, and the other is the secondary. The low MU > powdered iron toroid was picked over time to avoid heating, still > provide required coupling, with other choices sometimes failing in > spectacular fashion. We have no information of our currently-used > winding method on the Amidon T300A-2 ever failing for any cause, > though we would not expect it to survive a direct lightning strike. > > With the isolation transformer, the antenna and FCP is entirely above > ground and not connected to anything else. We use a 5 megohm resistor, > in parallel with a non-resistor lawn mower spark plug, from the FCP to > ground as a static drain. The gap drains lightning induced voltage to > protect the resistor, the resistor drains wind, snow, rain static. > The resistor and gap protect the winding from a voltage puncture that > will grow into a carbon track to ground. > > 73, Guy. > > ** As reported in Dec 2011 CQ, Jan 2011 CW160CW contest, USA low > power unassisted, the 29 scores over 100K out of 335 scored logs in > class: > > Station, state, score, QSO, ST+PROV, DX > > K9AY WI 259,346 991 58 36 > W0UO TX 250,716 882 58 44 > K1EP MA 232,750 909 56 39 > K2AV NC 223,908 907 57 37 << No radials, 5/16 FCP > K8BL OH 203,328 819 58 38 > > KU1CW KS 197,885 795 58 37 > N2WN TN 191,090 640 55 42 > WB8JUI OH 190,372 852 58 38 > N7IR AZ 183,855 856 58 27 > W2TZ NY 178,633 723 56 35 > > > NA8V MI 177,030 793 59 31 > W4AA FL 173,619 494 56 45 > K1HTV VA 172,956 733 55 32 > W1WBB RI 161,550 654 55 35 > KU8E GA 152,613 615 58 35 > > W7RH AZ 135,369 500 55 34 > K4WI AL 128,520 509 55 30 > N9NCK WI 126,162 516 55 31 > KV8Q OH 125,741 674 57 20 > N9AUG OH 125,330 608 55 28 > > > W2TX FL 121,800 504 52 35 > K9QVB IL 120,120 641 56 21 > WW3S PA 119,848 706 55 16 > K2UF NY 119,392 541 53 29 > K0PK MN 118,400 678 58 16 > > WF4U UT 114,239 664 56 15 > W1BYH MA 106,444 404 54 35 > W5WMU LA 106,020 574 54 22 > N4JF AL 101,920 493 54 26 > > ** 3830 claimed scores listing of Dec 2011 ARRL 160 contest, North > America low power unassisted, top 20 of 119 listed as of this writing: > > Station, state, score, QSO, ST/PROV, DX > 2011 ARRL 160 - 3830 Claimed Scores 06Dec2011 > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > Call QSOs Sec Cntry hr Score Club > NA Single Op LP > K8FH 920 74 18 27 175,076 Medina 2 Meter Group > NE9U 978 75 14 172,927 MWA > K4FT 976 75 9 28 166,236 KCG > WB8JUI 940 71 9 21.32 152,560 > K0TI 920 76 5 21 150,255 MWA > K0DI 875 75 8 28 146,495 Lincoln ARC > K2AV 788 65 9 21.5 119,066 PVRC << No > radials, 5/16 FCP > W0DLE 725 74 3 21 112,343 Grand Mesa > K9MMS 653 74 10 16 112,224 SMC > K0PK 657 72 6 19 104,130 MWA > > K3PA 618 74 7 101,817 Kansas City DX Club > WA1FCN 645 68 7 99,864 ACG > K2ZR 695 64 4 20.0 90,112 Western NY DX Associ > K0AD 584 75 6 10 88,500 MWA > W0UO 519 71 9 14 85,680 NTCC > K0CN 478 73 11 83,076 MWA > N1IX 516 60 10 13 78,540 YCCC > VE3OSZ 442 68 15 77,854 CCO > W9ZRX 492 69 8 20.5 77,616 SMC > W7RH 437 72 8 76,869 Arizona Outlaws Cont > > > > On Sun, Dec 4, 2011 at 8:18 PM, Jim Miller Waco Texas WB5OXQ > <[email protected]> wrote: >> With limited space what is the best antenna for 160? The only room >> available is a 130X50' area. Ground radials will be nearly impossable to >> put in large enough to be of much value. 1/4 wave antenna tried, very >> narrowband and interfeared with every receiving device in a block. I may >> just be out of luck. wb5oxq >> _______________________________________________ >> UR RST IS ... ... ..9 QSB QSB - hw? BK > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
