at the transmitter end of feedline will stop RF from entering your equipment and reduce receiver noise caused by common mode currents. The yagi plays the role of a ground plane, while the tower plays the double role of reflector and grounding "rod". Resources listed under End-Fed Antenna category belongs to Antennas main collection, and get reviewed and rated by amateur radio operators. One advantage of the end fed half wave antenna over an end fed "random" wire antenna is that it can be used on bands harmonically related to the band it is cut for without a tuner. The need for expanding an End-Fed with such a "counterpoise" wire was already recognized well over a century ago! One other note. The classic sloper antenna is a top-fed 1/4 wave vertical antenna sloping down and away from a tower. The End Fed Antenna: Killer or Compromise? By design, ununs are wound is such a manner that they provide little or no RF choking. Figure 5 - Ideal End Fed Half Wave Length Antenna. So, one cut for 40 meters for example, can be used on 20, 15 and 10 meters without a tuner.To use it on 30, 12 and 24 meters does require a tuner. This article is of a "homebrew" nature which includes a "review" of my experience using a 10-40m HEARC (Honolulu Emergency ARC) end fed matchbox antenna installed in a unique way from an RV park. This antenna is a half wavelength at the lowest frequency of operation, and then as the other bands on which t can be used are harmonically related, it provides a multiple number of half wavelengths. The exact impedance of an end fed half wave length antenna has been debated but if you design a coupler to match close to the impedance range in figure 3 a good match can be obtained. 12), just like all antenna radiators. End fed / long wire antenna Multiple wavelength long wire End fed half wave antenna W3EDP antenna The end fed half wave antenna is an attractive option for many radio hams as it is able to provide multiband operation without the use of traps or stubs whilst occupying a minimum amount of space and not presenting a very ugly visual impact. This antenna has been made popular by the Emergency Amateur Radio Club of Hawaii (EARCHI). Obviously the end-fed radiator does need something to "push against" (ref. T his program models a wide range of end-fed antennas used with a ground system of radial wires. In the search for the “Wonder Antenna” that is small, portable and easy to setup, I’ve decided to build an Endfed antenna using a 9:1 match. End fed half wave antenna: One method of providing a multi-band antenna for the amateur radio or ham bands is to use an end fed half wave antenna. Although not necessary, a 1:1 isolation/choke balun (models, 1110, 1113, 1115 etc.) It consists of 30ft of wire fed into a 9:1 UnUn (Unbalanced to Unbalanced). It might seem that an "end-fed" is a monopole antenna: there is no explicit "counterpoise" in most end-fed designs. The sloper's feed point is anchored high above ground near the top of the tower on which sits a grounded HF yagi beam antenna. … Continue reading "Portable Antennas: The EARCHI End Fed" Problems With End Fed Half Wave Antennas •#1 Problem: Common mode currents on feedline •RF in shack •High noise levels on receive •Feedline and grounding can affect SWR and tuning •Isolating the feedling from the antenna can be difficult, even with a common mode choke •High voltages, even at low power •FCC RF exposure limits can be exceeded at low power levels For each model the inductance and capacitance values of three alternative impedance matching networks are computed to match to a 50-ohm line.
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