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discusses some of the more important aspects of the End Fed Half Wave (EFHW) dipole antenna. The frequency band is HF (40 meters), and the intended power is 100 watts. Interest in the EFHW antenna has increased significantly over the last few years. Perhaps the main reasons being: It is inexpensive and easy to build,
At end fed antennas a certain current flows into the antenna, but according to “Kirchhoff’s current law” a proportional amount of current must flow somewhere else. Without counterpoise this will be the outside of the coax cable.
End-fed half wave antennas are best for temporary antennas using low power and batteries, far from power mains and noise sources. They are more prone for problems near noise sources or consumer gear, and can easily exceed FCC RF exposure limits with surprising low power levels.
28 lip 2022 · There are lots of voltage – or end-fed antennas. The classic Zepp (named after the Zeppelin airship on which it was used) is a half-wave dipole fed at one end. The popular J-pole is also an end-fed antenna—a Zepp with the half-wave radiating element sticking straight up instead of being horizontal.
4 lut 2019 · A NEC model that includes the transformer helix helps demystify the end-fed half-wave (EFHW) dipole antenna using the autotransformer as impedance converter.
To help new hams prepare for the exciting world of HF opening up during Cycle 25, ARRL has partnered with HF Kits to bring you this easy-to-build four-band antenna kit: an end-fed half-wave (EFHW) antenna.
Center-fed dipoles require two supports for each end of the antenna. A monopole antenna is like a center-fed dipole, with one-half of the antenna being the reflected image of the radiating wire inside the ground. For the Zeppelin which does not have a ground, it was more convenient to be able to support the antenna from one point only. To do ...
