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6

From some research, beam antennas only seem to come as monoband antennas. Not true — actually 20/15/10m tri-band beams are very popular. Multi-band yagis come in two basic flavors. Trapped. Works on the same principle as a trap vertical to alter the effective electrical length of the elements at different frequencies, except there are way more elements to ...


6

The elements of a Yagi are dipoles. If you look at a dipole at any instant, the voltage at one tip will be some value, and the voltage at the other tip has the same magnitude, but opposite polarity. So let's say at some instant, the left side is at +50V and the right side is at -50V. Consider these relative to the soil at the base of the mast, if you like. ...


5

I suspect your results are an artifact of your optimization methodology. I simulated the design described in the link with NEC2 using the EZNEC front-end. For reference, EZNEC calculates the gain as 13.03-dBi in free space with 2-mm diameter elements (the link doesn't specify element diameter). I believe this is close enough to your model's gain of 13.6-dBi ...


4

Some general hints from my experience: Use wires not printed metal. You could stop the print for a while to drop in the wires, then finish it, or push them in later. For sanity's sake, design your yagi to use identical directors, and make or buy a wire cutting machine to produce lots of wires of the same length. Plastic will have an effect on tuning - the ...


4

Engineer999. The driven element of a yagi antenna is normally a half wave dipole, and it's true that a dipole antenna is resonant on multiple harmonically related frequencies. An ideal 10 m long dipole for example is resonant on 15 MHz, 30 MHz, 60 MHz, 120 MHz etc. However the distances between the elements along the boom of a yagi required to provide ...


3

There are many properties of an antenna that could be optimized: Maximum gain Beam width Front-to-back ratio Feedpoint impedance SWR bandwidth Robustness to manufacturing variation Typical designs aim for "pretty good" in all of these parameters. Optimizing for one parameter exclusively will typically come at the detriment of others, and result ...


2

Not likely. To the best of my knowledge, any "metal filament" that's printable with a home 3D printer is PLA with 10%-50% of metal powder. This is good enough to make prints that look and feel metallic, but it's not enough for good electrical conductivity. Most likely it won't work as an antenna at all; definitely it won't have positive gain in any ...


2

The ARRL Antenna book has an article on stacked yagis that covers this. It states that colinear yagis have the elements end to end, not the booms. This could be horizontally polarized antennas horizontally stacked or vertically polarized antennas vertically stacked. Alternately, they can be stacked side by side, with horizontally polarized yagis being ...


2

You are using a high enough frequency to be considering patch antennas as a practical solution. You may try to calculate the size with this site : https://www.pasternack.com/t-calculator-microstrip-ant.aspx With a standard 4.4 FR4 PCB it gives you a size of 38mm x 29mm. If you print yours on JLCPCB for example you may even be able to put two patches on a PCB ...


1

A resonant 20 meter monoband Yagi will not work on 10 meters. Have you considered a 3-band 10-15-20 Tri-bander? It is a beam, and definitely not a monobander. There are also smaller tri-band directional beams, such as the Hexbeam.


1

It's is my understanding, from my days taking the advanced radio license, is that as RF travels along the surface of the driven elements, and that the reflectors and directors should be the same diameter as the driven elements, coupled with the fact, again to my understanding, that the greater the diameter of the elements increases the bandwidth of the ...


1

Bandwidth of a yagi is largely controlled by the diameter of the elements. Generally, the larger the diameter, the larger the bandwidth. However, the yagi is also helped by very slightly tapered elements. The impedance matching network may also affect the SWR bandwidth. The boom conductivity does not affect bandwidth, as well explained by Phil.


1

The demo version of EZNEC software (free) would be able to do that, with a fairly short learning curve: https://www.eznec.com/demoinfo.htm


1

The driven element length is chosen to give the right impedance for your matching network. There's no rule about it being longer or shorter than anything. The directors(s) are always shorter than the reflector(s) because their self impedance, combined with their spacing, is important in establishing the correct currents on each element. (of course I mean ...


1

It doesn't makes sense that a 6 element yagi doesn't work a good as a half wave dipole. Even a 6 element yagi with the worst design should still work better than a half wave dipole. I don't think the antenna is the problem. It sounds to me like one side of the feed line is open circuit at the antenna, if you are using coax the shield might not be connected. ...


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