Dipoles are often a go-to Antenna for many. But how much of a compromise is it if we have to squeeze in an inverted-V? Connect with my channel by subscribing and commenting.
Hi Tim, I've a mosly 5 band yagi, with one element on 17M, little or no gain..It's 10M above the ground and I've worked JA a few times on 17M with 100w. 17M is an underrated band, great for exotic stations...
Some of your viewers might not know that antenna gain is the product of antenna efficiency and directivity. It’s helpful to consider those two contributors separately when comparing the two configurations. If we ignore the presence of the ground, both the straight dipole and inverted V will have very similar broadside directivity. But the bend should broaden the elevation pattern, reducing the directivity straight up and spreading that power over a wider angle. Their radiation efficiency should be identical. Now consider the ground. Assuming both antennas have the same maximum height, the inverted V will obviously have a lower average height. Near broadside we have horizontal polarization and the ground reflection pushes the peak of the lobe to a higher elevation angles. The lower the antenna the more that lobe moves. That can be an advantage or disadvantage, depending on the distance you are trying to reach. Up to here I’m ignoring ground losses. They will have an effect on radiation efficiency as the antenna height decreases, but at typical heights I suspect that’s a relatively small contributor to gain compared to the effect on directivity. You mentioned that the inverted V provides a closer match to a 50 ohm feed. That’s true, but I don’t think a mismatch to a 70 ohm feed of a high dipole is much of a hit to radiation efficiency or SWR loss in a typical feedline, so it’s not a deciding factor. The above observations are based on general knowledge not calculations, so if someone finds a misstatement feel free to point it out.
In photography, we call a certain group of people "pixel peepers". This group of people look for pixels or specific details no one else "in the main" would ever see in a photograph. Well, I've noticed in ham radio, we also have a group of folks called "radiation pattern peepers". This group of people look for different radiation patterns, like between the inverted V and Flat top. Bottom line is, no one would be able to tell on the receiving end what antenna being used between the 2 antenna's. However, having said that, I feel this information is very useful from an academic perspective in learning how different things change as changes are made to the antenna. So, really good information. However, I can't stress enough the diagrams/FF plots etc. look larger than they actually are. Meaning many of these changes in signal strength are minor, but the graph makes it look like a huge change. Hope that is constructive in my best opinion :) Best Regards and 73
Thank you so much for your explanation about these kind of antenna. 😊 but some reason i still choosing inverted vee antenna:🙏🏻👍🏻 in the Bonsai type model😁
(copying to a main comment from my reply) One of the huge benefits of an inverted-V, or in my case a double inverted-V (in our club we call is a cross-V) is that it can be self supporting with a single mast. I setup mine for about 120 deg included angle with legs for 20 and 40 meters and can easily work 15 on the 40m legs since it's the 3rd harmonic. More bands "work" with most radio's built in 3:1 tuner. Perfect for EMCOMM where most of your work would be
Good analysis Tim 😀 I think in practice it would be hard to notice the sometimes subtle differences between the two 🤔 However, having two options gives you variations to get as much wire into the garden as possible and as high as you can , as these two factors will probably be more influential? I think the different mounting options of flat versus V is also a positive when it comes to what’s possible in the given space 👍🏻 Thanks 😀
I remember being a kid with not much money and having to make an inverted V and taped it to my bedroom wall lol. It was a bit directional but it worked.
These models are great, and show, I think, that they are basically equivalent because the point to point path and signal reliability will depend much more on conditions, which change unpredictably in both time and space, than the differences in these two configurations. That is, 1-2dB here or there, or a few percent here or there, on the antenna, is
If the radiation pattern of a center-fed dipole is circular around its axis, can't it be turned to the vertical orientation to be an omnidirectional antenna? If so, how high off the ground would it need to be mounted? 1/2-wave (so the "top" would be 3/2-waves of the ground) or is it more important to have the upper element 1/2 wave off the ground( which would essentially have the "ground" side near the ground). In my case for a CB (11M) antenna. Another question about the "Inverted V" dipole: when the "V" is 90 degrees, doesn't that tend to make it an inverted ground plane antenna?
For the vertical Halfwave dipole as with the horizontal version, the max current is in the centre part of the antenna so enabling this to be as high as possible is good. However, you do have an omni directional pattern and the key is to try and get the lower leg as far above ground as you can (and away from the reach of people as voltages will be high at the ends).
As an Antenna can't have a power gain it's all swings and roundabouts. Affective gain just means that the power you have is being funnelled in a particular direction. So if it's omnidirectional then the gain will be zero or less due to losses. hence to get high affective power gain you need to be able to rotate the antenna as the beam width will be reduced to a narrow angle. My G5RV with the centre at about 12m is great to some places and C**P to others. I've gained on the swings but lost on the roundabout. Just waiting for the 17m 4ele at 20m to fit within the bank balance. ;-)
Comparing inverted-V (downward pointing) with a flat dipole made me want to see what would happen if the angle continued upward into an upward-pointing V. I don't expect that it would make an effective antenna since I've never seen anyone use such a thing, but I would love to know what happens to the feedpoint impedance and radiation pattern.
@@alzeNL Exactly. One of the huge benefits of an inverted-V, or in my case a double inverted-V (in our club we call is a cross-V) is that it can be self supporting with a single mast. I setup mine for about 120 deg included angle with legs for 20 and 40 meters and can easily work 15 on the 40m legs since it's the 3rd harmonic. More bands "work" with most radio's built in 3:1 tuner. Perfect for EMCOMM where most of your work would be
