A very important caution about the performance of T-verticals vs. Inverted-L verticals.
If the performance of your 40 meter antennas is important to you and your T-vertical is within 300 feet of your 40 meter antenna, its important that the top of your T should be less than 55 feet long or more than 80 feet long. Why? If the T-top is 55-66 feet long it will act as a 40 meter director. If its 66-80 feet long it will behave as a 40 meter reflector. Don't ask me how I discovered this... If the top of a T-vertical needs to be 55-80 feet long and within 300 feet of a 40 meter antenna that you don't want to degrade, its better to use an inverted-L vertical, which has little or no affect on nearby higher frequency antennas. 73 Frank W3LPL ----- Original Message ----- From: "Guy Olinger K2AV" <[email protected]> To: "Jerry Keller" <[email protected]> Cc: "REFLECTOR: Topband" <[email protected]> Sent: Tuesday, December 6, 2016 5:05:37 AM Subject: Re: Topband: Inv L Config The horizontal section also radiates, more or less than the vertical depends on the specifics. Easy to see in a very simple NEC model. If you are opposed to radiation from the horizontal on principle, then put up a T. But the radiation from an L's horizontal fills in the doughnut hole in the pattern, essentially getting the energy for that by taking it away from ground losses. Assuming that on 160 one has RX antennas because TX antennas are notoriously noisy, then you only care about what happens to TX. Filling in the doughnut hole helps to minimize or eliminate skip zones, and help keep a run frequency running low power. The effect of a particular change to wires applies more to where the current is more. Given that, doubling the vertical wire is what you do. But I would model that and see what it buys you. Do the change both in free space and over ugly dirt. 73, Guy K2AV On Mon, Dec 5, 2016 at 11:37 PM, Jerry Keller <[email protected]> wrote: > Is it advantageous to make both the vertical and the horizontal sections > "fat" (for improved bandwidth), or is it enough to "fatten" the vertical > (radiating) section ? How much BW will 3" diameter spacers give me? > > 73, K3BZ > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband > _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
