Vee-Beams
- skylarkcolo
- Nov 1, 2024
- 5 min read
Updated: 22 hours ago
The Vee Beam (V-Beam) is just one half of a Rhombic.
I am using, two 1200 foot per leg Vee-Beams, to fill in a few directions where I could not add four poles as required for the rhombic. I don't see much real day to day difference form the rhombics, However these are very long Vs, even a 300 foot would provide good gain on the higher HF bands and work on 40 meters.
A great V beam 40 -10 meter setup would be two or three, 400 to 600 footers on a rotary switch, using just one tall support. A Vee Beam is a good and very low cost way to go, if you have a large lot. Which has the same gain as a 3 or 4 element mono-band beam, however providing that gain all those bands.
V-Beam Basics
The terminated V array forms a Vee-beam, that is, a directional terminated V array. The technique seems simple enough. We simply place a non-inductive terminating resistor at the end of each leg. However, the resistor cannot simply float at the terminating end of the wire. One option is to bring the terminated end of the leg wire to ground. Alternatively, we may run a wire between the two terminated wires end and place the non-inductive resistor at the center.Optimize for Frequency and Design
Tailor the Vee beam antenna's dimensions (length and angle) to the specific operating frequency for maximum radiation efficiency
Use simulation tools to refine the antenna design and predict its performance before construction
Reduce Side Lobes
Adjust the V angle and element lengths to concentrate more energy in the main lobe and reduce side lobes, which can waste power and pick up noise
Ensure proper impedance matching between the antenna and the feedline to reduce signal reflection and maximize power transfer. Use only highest quality balun. The Proper impedance matching between an antenna and its transmission line is crucial in maximizing signal efficiency and reducing unwanted reflections, that can cause major losses in RF power going to the antenna. Impedance matching keeps the impedance of the antenna and the transmission line the same in order to see the least amount of signal per watt lost. Remember there is no SWR on a traveling wave antenna. It's only the mismatching between the 600 to 800 ohm of the antenna, and the 50 ohm transmission line, that creates it.
Resistors at the ends of a traveling wave antenna, like a Rhombic or V beam, serve to absorb the radio-frequency energy that reaches the end of each leg, preventing it from reflecting back along the wire. This absorption ensures that the current remains a traveling wave rather than forming standing waves, which would otherwise reduce directionality and bandwidth. By matching the resistor value to the characteristic impedance of the antenna leg, reflections are minimized, maintaining the unidirectional, broadband performance of the antenna
Resistors help sustain a stable traveling wave in antennas by absorbing the energy that reaches the ends of the antenna, preventing it from reflecting back and forming standing waves. This absorption ensures that the current maintains a progressive phase along the antenna, supporting unidirectional wave travel and stable radiation patterns. By matching the resistor value to the antenna’s characteristic impedance, reflections are minimized, resulting in consistent traveling wave behavior and improved directionality and bandwidth
Operation: Rhombic and V beam antennas are true traveling wave antennas, meaning the current propagates along the wire and radiates as it goes, with little reflection at the ends. In contrast, the Yagi antenna uses a combination of driven and parasitic elements to shape and direct the radiation pattern, and its current distribution is a mix of forward and backward waves due to mutual coupling.
Directivity and Gain: Both can achieve high directivity,
Bandwidth: V beams and Rhombics have broader bandwidth, while Yagis are more frequency-specific
An easy low cost high gain array: Just add more Vee Beams on a tall support, and run them out in multiple directions, they can even slope back towards the ground. Install them as high as you can, from a tree, pole or tower.
The above, is a switch box using 10 amp relays to switch the open wire feeders.
The terminated Vee array forms a Vee- beam, that is, a directional terminated V array. The technique seems simple enough. We simply place a non-inductive terminating resistor at the end of each leg. However, the resistor cannot simply float at the terminating end of the wire. One option is to bring the terminated end of the leg wire to ground. Alternatively, we may run a wire between the two terminated wires end and place the non-inductive resistor at the center.Fig. 6 shows 4 classic implementations of the terminated V-beam. Model A places the feed=point close to ground and slopes the legs upward to their normal (1 wavelength) height. (The opposite slope for the array is also possible. See model A1.) The terminated ends run vertically to the ground, with the terminating resistors at ground level. The model will use the same ground-rod technique used in constructing models of single terminated long-wire directional antennas. However, none of the models will use a vertical wire at the feed=point end. The single long-wire beams could use the vertical feed=point end with the actual feed-point close to ground. If we apply that same technique to the V-beam, we end up with the 2 legs in parallel, which does not yield much gain or directivity.
The source-ends of the legs must have the feedline across them in a series connection to yield the correct addition of peak lobes from each leg.
Selecting the correct values of the 2 terminating resistors is not so simple as it was with the single long-wire beam. As the following trial table shows, the value is not exceptionally critical, although we may have reasons for choosing one value over another. For design purposes, the reasons may involve the best compromise among gain, front-to-back ratio, and impedance. In practical installations, the reasons generally focus on what non-inductive resistors may be available. The test table (and others to follow) uses NEC-4 models with 5 wavelength legs 1-wavelegnth above an average SN ground.
Terminating or not see below
So where to find large non-inductive resistors are used to terminate the antennas
W7YRV/SK used a 200 foot tower and spaced 9 sets (18 wires) of V beams, 360D around the tower. Then he used two sets each to form his "W7YRV X- Rhombic", such a great antenna that he used on 80 meters and up. When in QSO with him on 40 meters he would just start rotating it, and the S numbers at my QTH in KS, would change by one to two S units on each switch, running a 1000 mile day time path. 40 over 9 with a KW, to S2 or 3 in the noise. He gave me his switch control unit. I will write more on this system later, also see his blog which is still up. http://w7yrv.blogspot.com/2013/
Feed System info
See
TO SEE the complete Blog list check @ https://www.k0uo.com/k0uo
Easy to build a High Gain directional antenna system at very low cost. 300ft V beams
Good info