John, IMX any product that uses "Miracle" in its name isn't, Hi!, especially when transmitting. You can get away with a much reduced antenna when only receiving more easily than if you want to transmit.
The efficiency of any antenna drops as it is made shorter than 1/2 wavelength (130' on 80 meters, 66' on 40 meters, 33' on 20 meters, etc.) An antenna only 1/4 wavelength long can be pretty nearly as efficient if you pay close attention to minimizing losses in the ground system if end fed. Below that the efficiency literally plummets. The drop in efficiency is not linear but accelerates as the antenna is made shorter. In large measure that is due to the resistive losses in the antenna and matching network conductors. We know how to avoid those losses. Use a super-conductor for the radiator and in the matching network. Unfortunately, I don't know where to buy room-temperature superconductors. Until we can, we're stuck with those losses. We're not talking about the resistance your DMM might show. RF flows over the surface of a conductor, not through it. Currents flow only in the very outer layers of atoms in a conductor so the resistance at RF is far greater than your DMM indicates. We can minimize those losses by plating all the conductors with silver or gold. But that costs money and only partly helps. Even so, it's what high-quality RF circuits use. Another critical point is in the sliding contacts used in switches, variable capacitors and telescoping antennas. Under the best of conditions they are lossy. Sometimes we must put up with them, but we're paying a big penalty in efficiency. The issue with the "Miracle Whip" is that it does not address any of the loss issues very well. It uses a telescoping whip and inexpensive components in the matching network. And then there's the height above ground and distance from surrounding objects. The closer you are to the ground or other objects the more RF current is induced in them. That RF is simply lost. You'll hear Hams referring to it sarcastically as "warming the worms" Hi! Sometimes we simply must accept the losses to get the portability we need, but there is no "magic" solution, no new technology, no newly discovered principles, that will help. It rather sounds like one can't get out of their own back yard with a tiny antenna, but it happens every day. Under the right conditions even a few thousandths of a watt (milliwatts) getting radiated can be heard over a long distance. But a larger antenna, at least up to one at least 1/2 wavelength long and well clear of the ground and other objects, will do much, much better every time. Good luck getting your license! It's a fun hobby. 73, Ron AC7AC -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of John Stears Sent: Monday, March 05, 2012 12:02 PM To: [email protected] Subject: [Elecraft] Why did I purchase this antenna for the KX3? Good afternoon, I am a very new (receive only/studying for license) enthusiast caught up in the excitement here and for the loaded KX3 that I have on order. Could the group please give me some kind of idea as to whether this purchase http://www.universal-radio.com/catalog/hamantht/5046.html was a wise one for this unit given that I now see it has an antenna already attached to it (doh!).or is this 'improved'(?) antenna as good as any other (in 2012/regardless of cost) for increasing performance while still keeping the whole package compact and portable? Thanks for any help as I'll stick with the stock whip if this product isn't a good match and concentrate my funds on whatever fixed base setup you guys agree on that is still portable and most importantly the best on the market as of this year. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
