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## Re: Topband: T-antenna dimensions?

 To: mrscience65704@yahoo.com, topband@contesting.com Re: Topband: T-antenna dimensions? wd8dsb@aol.com Mon, 18 Jan 2010 12:48:57 EST mailto:topband@contesting.com>
 Hello Mike, EZNEC model of a T configuration using a 50 foot vertical section indicates each leg of the T needs to be 61 feet long (total length of the top of the T would be 61 x 2 = 122 feet), and this is based on resonant frequency of 1.82 mhz. Input impedance will greatly depend on the number of ground radials you use. With perfect ground you should expect an input impedance of approximately 12.2 ohms. With an average ground (no radials), you should expect an input impedance of around 66 ohms. With ground radials you will have something in between, and as you add ground radials you will start approaching the 12.2 ohm value at resonance. A good way to match the T to your transmission line with very low loss in the matching network would be through the use of a simple L network. 73's Don Kirk (wd8dsb) In a message dated 1/17/2010 10:44:57 P.M. Eastern Standard Time, mrscience65704@yahoo.com writes: Now that I can hear very well (Two 2-wire bi-directional Beverages), it's time for a transmitting antenna. I want to play in the contest during January 29-31, and time is running out to put up a transmitting antenna. I don't have a tower at this time. I have some trees picked out for a T antenna, between a section of pasture where it's easy to lay down a lot of radials. I can have a 50' vertical section. But I'm having trouble finding what the approx. dimension of the horizontal portion at the top should be. Any advice would be appreciated! 73, Mike Waters W0BTU _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
 Current Thread Topband: T-antenna dimensions?, Mike Waters W0BTU Re: Topband: T-antenna dimensions?, Herbert Schoenbohm Re: Topband: T-antenna dimensions?, Richard L. King Re: Topband: T-antenna dimensions?, wd8dsb <= Re: Topband: T-antenna dimensions?, Mike Waters W0BTU Re: Topband: T-antenna dimensions?, Herbert Schoenbohm Re: Topband: T-antenna dimensions?, Mike Waters W0BTU