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9

The cheapest antenna you can set up is a speaker wire dipole. A spool of speaker wire long enough to split the conductors and make a center fed half wave dipole ought to cost around ten dollars US (or less). You can get useful radiation with supports made from cheap stud lumber from the home improvement store (8-10 dollars per support to get 5 meters off ...


4

Does this mean this antenna can't be tuned to the 160M band, or does this just mean that the impedance is so different from 300 ohms that the SWR is useless? A little bit of both. If you get an off-the-shelf matchbox, which is usually advertised as being good for a 10:1 range or even less, then you can expect that it won't be able to make this antenna do ...


4

The most general answer to this question is that you neither include nor exclude the gap between the elements. Rather, whatever is going on there is part of the antenna design. Physics doesn't care which things we call “antenna elements” and which things we call “wiring” — the shape of all conducting elements matter. To match theory and reality thoroughly, ...


3

Hello and welcome to the hobby! Generally speaking, it depends on your conditions and area available. Assuming it's not a problem (e.g. you live in a suburb area and have a backyard or are willing to travel to the nearest forest) the simplest, cheapest and quite efficient antenna you can build is a dipole / inverted-V. There are a few ways to build one. I ...


3

In this context, loading is used to make an electrically short antenna resonant. In an electrically short vertical, moving the loading higher is almost always an improvement because it raises the point of maximum current, where the majority of the radiation takes place. Center is better than base loading and top loading is superior to center loading. Top ...


3

Wire antenna are usually the easiest for beginners. The standard is a dipole with 1/4 wavelengths on each side connected in the center to your coax. Another easy antenna is a end fed half wave. It requires a bit more equipment as you need a transformer to match the high impedance. You can buy or make your antennas. Home brew antennas are a popular way to ...


2

Read it off this chart: Interferometrist [CC BY-SA 4.0], via Wikimedia Commons A folded dipole with equal-sized conductors has 4x the impedance of an ordinary dipole. The impedance repeats every wavelength, so for example if you're interested in the impedance at 2.5 wavelengths (off the chart) it won't be far off from the impedance at 1.5 wavelengths. ...


2

Your question does not have enough information to give a specific answer, so here are some general guidelines. The type and size of wire needed is unrelated to the antenna. The factors that are important here needed to answer your question are: the maximum power you will transmit with the amount of loss you can tolerate (greater distance has more loss) the ...


2

I used EZNEC (NEC2) to model a λ/2 dipole in free space. The program reports the voltage very close to the end of the dipole as 3910 volts with 100 watts of driving power. The resonant frequency of this dipole was 14.27MHz. Moving to 14MHz resulted in 5392 volts at the end for the same 100W power input to the feedpoint. Moving to 14.54MHz resulted in 4536 ...


2

Eventually I managed to make the antenna work on more than one band. I used a modeller (CocoaNEC) to approximately determine the impedance on each band of interest for my antenna configuration (inverted-V on a 10m long fishing rod). The impedance was about 2450 Ohm. Thus I rewinded the transformer to 1:49. Also I used a 1:1 balun (8 turns of RG58 on FT240-31 ...


1

Using a closed loop whose circumference is only about $\lambda$/4 puts it in the regime of a "small" transmitting loop. This online Small Transmitting Loop Antenna Calculator gives remarkably similar results to NEC simulation using only formulae from the ARRL Antenna Book. It's particularly interesting to observe the effects of increasing conductor diameter: ...


1

There are at least two ways. Firstly, you can use the antenna modeller (I prefer cocoaNEC) to estimate an impedance of the antenna at given frequency. From personal experience it doesn't work that well though. The real antenna will differ quite a bit from the model because of unknown ground properties, various metal object near antenna, etc. This method may ...


1

The antenna in the left foreground is probably a conical monopole, as described by E.W. Pappenfus, WB6LOH, in QST for November 1966. Antennas of the size order shown in the OP are probably for use from 4MHz and higher in the medium-wave band.


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