Everything you apperceive about dipole (calculators) is amiss …
The added day I did an experiment. I searched for “dipole calculator” and application the aboriginal 20 after-effects I affected the breadth of a dipole acceptable for 7.130 MHz. I chose the abundance for no added acumen that there is a 7130 DX net every Monday, Wednesday and Friday and for the longest time I’ve been clumsy to participate due to the abridgement of a HF antenna in my new shack.
So here’s some things I learnt from accomplishing this experiment.
Depending on which calculator I use, the breadth of my dipole can alter by over a beat from longest to beeline result.
Depending on my admiration to use metric or administrative measurements, my dipole will be a altered length, because of advance electrons move at a altered acceleration if you’re not application the metric system.
In case you’re wondering, 1 inch is authentic as actuality absolutely 2.54 cm, so there’s affluence of befalling to alter that.
Speaking of standards, we all accede that the acceleration of ablaze is a constant, right? Turns out that for some calculators, you can change the acceleration of light.
I’ll skip over the angle that none of the calculators absolutely appearance what they’re application as the acceleration of ablaze and move on to added absorbing discoveries.
Apparently you can actuate the breadth of a dipole bottomward to the sub-atomic length, with one calculator activity bottomward to the admeasurement of an electron to announce how abundant wire you should cut from a spool.
There are forms that accomplish accomplishing the adding absolutely easy, distinct box to blazon in the frequency, so the acknowledgment charge be right.
There are some that use accidental accepted numbers, alike a argument book archetype that uses some number, but no adumbration area it comes from. For example, the cardinal 486 appearance regularly, but so does 150 and 5905.
There are forms that accommodate you with several boxes, but no adumbration which box needs what value, so your acknowledgment may or may not announce the cardinal of eggs per craven per parsec.
One dipole calculator aftereffect is absolutely for a vertical, so your chase agent allowance you ability not absolutely accord you the calculator you expect.
There are allotment alteration factors. 5% seems to be a favourite number, but no adumbration as to what the agent of that cardinal is.
There’s a calculator that allows you to specify the augment point impedance, not abiding how that works, but it’s a nice affection to accept back you’re artful the breadth of your dipole. Not.
One approved apprenticeship is to cut long, that is, admeasurement your wire and cut it best than the calculator states. How abundant best is larboard as an exercise to the reader. Should it be 1 mm longer, 1 cm longer, or should it be 1 m best and how abundant should that change if the abundance changes?
Let’s move on. The chat arena appearance heavily in these calculators. The byword “average ground” does too. No adumbration as to what makes an boilerplate ground, or how to go about chargeless what changes if your arena isn’t average.
We all accede that the dipole should be bisected a wave-length aloft the ground, right?
How abundant is that?
The aforementioned beachcomber breadth as the breadth of the dipole we’ve aloof calculated, or a altered one?
How does the breadth of the dipole alter if the acme varies? While we’re attractive at variation, how abundant aberration is there depending on how blubbery the wire you’re application is and what about insulation? None of those things are alike mentioned in any of these calculators.
Dipole calculators, admirable invention, abashment about the implementation.
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