End fed vs ocf dipole. This antenna is often called a center-fed Zepp, although any similarity to a true Zepp antenna is purely visual. The picture on the right above shows an OCF Dipole with the feedpoint positioned at the same feedpint of the classical WINDOM antenna, fed with 50 Ohm coax through a 4:1 or 6:1 balun at a point 1/3 of the distance from one end. Up is 0°. I have some tall trees nearby I can hang it in, semi-permanently. 7 MHz instead of the expected 21. But the reason end-fed antennas are so popular with portable outdoor operators, such as POTA and SOTA etc, is that end-fed antennas are easier to erect in the field. These designs can operate on multiple bands. They are typically half-wave antennas and are the simplest and most widely used type of antenna. Jul 4, 2021 · Michael: And then finally Robert asks, what’s a better choice for multi-band antenna. Off-Center Fed Dipole Long / Random / End-fed Antennas An end-fed wire often seems like the simplest type of antenna, but getting it to work well is actually rather complex. The BULLET-4006 uses the same dimensions but the wire section is 55 feet as in the OCF and the coax outer braid is used for the “other” part of the OCF dipole. This is the length of a standard dipole but instead of dividing the result in half, use a 36/64% offset to determine the feedpoint. The 2-λ end-fed wire has 8 lobes. Sketch of the Off-Center Fed Dipole What I’m going to do is move the feed point from the center of the dipole (50%) to four other positions: 65% from the left end, 70% from the left end, 75% from the left end and 80% from the left end. The included angle between the arms is 120°. I always do an end-fed wire first thing, as long as possible with a 1:9 unun and a tuner. Jan 7, 2024 · Date 1 - 11 of 11EFHW vs OCF The horizontal wires of the folded dipole were 128 feet, 2 inches long and the vertical end wires were one foot in length. co. Center support is a fiberglass mast. Then folding the ends back part way or into triangles. Hence, a 1⁄2-λ end-fed wire has two lobes (that are virtually identical to those of a 1⁄2-λ center-fed dipole), but at 1 λ, we find 4 lobes. Design Goals and Objective: Construct a multi-band off-center-fed (OCF) dipole covering the 40, 20, 15, and 10 meters amateur radio bands, and possibly the 6 meter band (but that is considered a bonus band, outside the main project objective. 7) is of actual measured data of an end fed half wavelength antenna with an isolated coupler using an 8:1 turns ratio. Being I have never used one, I am looking for opinions, advice, pros, cons or any other pertinent information relating to this type of antenna. When trimming wire on an OCF it is necessary to trim a proportionate amount off each side, not just equally off both ends as you would a center-fed dipole. An end-fed half wave is a dipole it's just fed at the end instead of the center. I am seriously thinking about an end fed as it gives me more options on location. This fact has a further consequence. 3' long) has a maximum gain of about 7. The direction of radiation is the Blue trace on the polar graphs. Here is what you need to know. We would like to show you a description here but the site won’t allow us. The shield of a coax feed line to an off-center fed dipole usually (always?) can't be centered in the dipole's EM field, thus is an off-center parasitic element. A dipole does NOT have 2. The OCF follows the general end-fed pattern of lobe development. For example, a center-fed dipole tuned to 7. The End Fed Half Wave Antenna is very popular at this time. Jan 11, 2010 — fed Windom, but rather an off-center-fed or "OCF" two wire feed dipole. In extreme cases, the short ends are so small that they are physically Jul 7, 2020 · I have never used an end fed antenna before, always used a Windom. My man-portable antenna requirements The following data are for the far field radiation patterns and 3D color views of a sloping End Fed Half Wave antenna with the feed point near ground and curving upward to 40 feet at the far end. Test shows field strengths are identical. In other words an 80-meter Windom 137 feet long would have one leg 45. The primary issues are: The impedance varies over a very wide range, depending on the length in wavelengths. Jun 15, 2021 · Does an end fed half wave have any better performance over a dipole? I have a 40 meter Hamstick dipole. Click on the link to connect to the product you need. 80m and 40m resonance is low, and 20m and 10m resonance is high placing the low SWR points at the band edges. END FED This is often called an EFHW (end fed half wave) that is, like the Windom and OCFD, approximately a half wave at the lowest operating frequency and which is intended to operate on the harmonics as well. Thought it’d be down from the wind overnight but I’ve been using it for months now. ayl tmt bkvr kma iawxf emmop gjieny7 ynquj 2qt2ke ogn