![]() This was the demise of Performance and Immunity. Three-legged fuses had impedances that matched it new problems arose which were further compounded by broadband front-ends. In their haste to exhibit their understanding of co-ax and the Three-Legged Fuses, ignoring the basic antenna theory they ought to have learned at their mother's knee, engineers used it everywhere.Īntennas were designed for it. So what else was new?Ĭo-ax was almost new. The Three-Legged Fuseīut then Three-legged Fuses came along to replace warmly glowing, EMP-immune glass bottles they called them Transistors. Low loss? Virtually no loss in practice.īy understandable means to us old-timers, including the use of warmly glowing, EMP-immune valves filled with excited electrons, the flow of which was deflected somewhat by the energy from the antenna, this lot used to be converted into an intelligible signal, the translation of which would be transcribed by the Operator in the soft, comforting light emanating from the dial of the receiver. The end-fed antenna was simply brought in directly to the receiver terminals via a healthy piece of copper tubing through a hole drilled in a plate-glass window. In the good old days, when receivers had real front-ends and the price of copper was reasonable, this was of little consequence. In fact they are almost universal and because of this they receive no more than a passing glance in the grand scheme of things. They are also found on military radios and the slower aircraft being used for communications and for receiving Electronic Navaids. Single-ended antennas, whether they be a short whip, an end-fed wire or an MF TEE, will only approximate a resistive match at odd multiples of the frequency at which the antenna achieves Quarter Wave Resonance and then only if the termination is with respect to a common ground, both for the feedline and the antenna itself.Īt all other frequencies such an antenna looks like an impedance in series with a resistance.Ĭoast Stations used them. In our corner, we still believe radio is fun as long as you follow the ground rules - puns being a cheap form of journalism - the most important being the efficient transfer of energy from aerial site to radio set. In one corner, the radio hams talk of antennas as religion. Co-ax Antenna Feeders - Low Loss Or Dead Loss?Ĭoax-fed antennas have become law during the development of the latest generation of radio sets. ![]() In short, if you are serious about SWL, get an ATU. Our picture show the simplest pi-tank but they come in all sorts of configurations. Use the preselection of an ATU to narrow the band and the radio stands a better chance. The ratio between them can be a million to one or greater, the quiet stuff getting lost in the shadow of the loud. ![]() ![]() In that band, signals large and small appear. This can improve signal-to-noise ratio, so improving your perception of the signal you want to hear.Ī modern radio passes a band of frequencies (band pass tuning or filtering) for processing. In fact, an ATU will pre-select the range of frequencies you want to hear and by default reject the rest. ![]() For us listeners, all we want to do is get whatever signal the passing wave has deposited on our aerial element, wire, beam or rod at whatever impedance transferred to an impedance our radio will like.ĭo that and losses are less, reception is better and with an ATU, you get a bit of free gain and a little less background noise.Īnd they are passive, no electronic gain to add noise and get overloaded by the local AM station. Whether receiving or transmitting, it's all about energy transfer. Make the antenna connection to your radio a match made in heaven. ![]()
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