a very good day now in the last couple of videos we've done we've done a vertical we've done a
dipole today what we're going to do is we're going to model a basic square loop which will take about
five minutes in the next one what we're going to do is we're going to turn it into a triangle and
we're going to make it two three four wavelengths bigger see what happens it's quite interesting
so the loop antenna now i've got one thing to tell you before we formally start
is that in under setup language a lot of people have discovered
that when it downloads at the moment in deutsch which is actually quite difficult to understand
so that's how you change it back right gonna make this a wee bit bigger so you can see it
nicely do we maximize it maybe yeah we'll do it like that you'll remember the geometry tab
the view tab the calculate tab and everything we're going straight in today to the wire edit
button and i'll maximize this as well i'll go to the x y will draw a square loop on the ground
which is probably going to be a wee bit too big we're able to find out how big is that 20 meters
we can shrink it in a minute there we are one square loop nice thing about this software is
you've got this little drawing tool because otherwise some of the professional
end of the modeling market you've got to know you've got to start working all this stuff out
okay so let me just view that and work out where we want to put our i'm looking at the x over there
let's put the feed point on this one here which it says it wire two so right click move add
source to the center of the wire now this is quite a big antenna so let's reduce it by a
factor of two by hitting the calculate button or scale button and multiply by 0.5 it should exactly
if the math has been right changed it all from tens to fives now let's make this for about the 40
meter band so if we're going gonna do that let's put 7.2 megahertz in i'm going to show you a new
toy a new tool today this isn't going to be 20 meters high if you're considering putting a flat
loop in the garden the backyard that is chances are it's going to be fairly low i mean let's just
put it at seven meters off the ground and we'll make it out of copper wire um something's going
wrong seven add height uh very often i'm in the it says perfect this is real world
okay we could go into ground setup not today i'm going to show you the swr calculator in a minute
we also know if it's a loop it would be 200 ohms so i'll be using a four to one impedance so we
go through these steps we go optimize advanced we go to the environment tab and we just put in 200
that's all we do by the way this won't change the far field plot it'll just make your swr look a
bit better on the chart it will not change the far field plot i'm just going to hit start now
and see what happens okay my swr it says here is 4.77 so if you were considering making this
a wee bit better at seven meters height what we can do is hit the now we're going to go into the
swr get the best swr out of it so let's find exactly where is its best swr so swr sorry
let's give me a 400 so just under 400 kilohertz just under half a megahertz and give me a detailed
plot please between 7.0 and 7.4 you can click that button detailed oh and you can see it's actually
gone off the scale it's too big so we can actually make that bigger or we could just click resonance
ah to help with all that where's it resonant okay best resonance i've got is 7.689 so in other words
it's a wee bit too small so let's just take a note of that seven six eight nine seven six eight nine
so we need to go here seven seven point six eight nine and that's now where it believes
this antenna should be so when i hit this button the scale button it'll go oh well you're at 7689
i know about speed of light and wavelengths and everything where's your target frequency
7.2 that's a multiplier of 1.0679 something and now you'll see all these numbers change a wee bit
right so now we can go back down to 7.2 and we will have an antenna under 2 to 1.
there we are 1.99 it might not be exactly right because relative to the earth the wavelength
has changed a few other things whatever where are you resident now that'll do
whatever i'm not worried about it says here it's got 100 ohms of beatens uh and a few other things
my swr i would expect that to be slightly higher but yeah if let just please don't worry about the
swr right now it doesn't actually matter and i can prove it to you because we went up a touch higher
all the numbers would start to work all right it's just that we're proportionally very low to
the ground for the maths 10 meters 30 feet i've got an s top 1.3 to 1 because the impedance has
gone up to 154 so that's why i say do not worry about this well we'll leave it at 10 meters
that's fine i can live with 1.3 to 1 and so can you so however long that is i think probably
about six minutes but anyway i've done that roughly in five so that's how you draw a loop
right we can go to the far field plot and just have a couple of look at the looks of things
you've got the currents on and off i'm currently driving on the right hand side 10 meters off the
ground where is most of our rf going that's quite interesting a lot of it's going oh there's x and
y uh there we are so x is over here and y's up here if we do elevation just ah daytime 40 meters
say 30 degrees over here we've got 1.9 bananas up there we've got minus 2.8 just over 3 db
difference and behind us so coax if you like going forward 1.9 2.3 worst case scenario so there's
nearly 6 db between one side and the back of the antenna i said the back because that's
where the feed point is and roughly that's where it is you can look at that as a far field plot
just see what it can do i'm sure it should be working in a minute oh i've got the new version
oh gosh five degrees i haven't seen this one before it's all in color how do we change this to
english i don't know oh there it is set up english hey done it ah there we are so that's how to model
a loop next time what we'll do is a much bigger plot we'll go to multiple wavelengths make it
triangular because some really cool things happen there as well in the meantime next
video is coming up here but jolly good day thanks very much for for joining me today bye for now