what happens if you're putting an antenna on sloping ground and there's plenty of reasons why
you would field a um you know you've got property line with a bit of a slope you know what happens
you can actually do a bit of a thought experiment of where are the gains where are the losses
why it's good and why it's bad and why it's indifferent so um let's do a thought experiment
okay this is the easy one this is so easy it's untrue let me just put an imaginary
gravity line there so that is the real real ground can we build an antenna on that ground
uh yeah out of blue let's say doesn't matter what antenna okay i'll model this in a minute actually
and just show you what happens with the sloping ground so great so far however how would you do
a thought experiment if the ground was sloping so we'll put our black line there again roughly
hopefully i'll get it fairly equal but this time we're going to move it around let's say about 15
degrees ah i don't know 15 degrees is probably about that much and we'll put our antenna uh
well i'll put antenna in red this time straight off off the ground which is a bit like building
an antenna that looks like that because all we've done is just shifted it around 15 degrees
so is the signal going to be better going down the hill or not so as part of this thought experiment
what we could do is go into our software and i'm just building a quick vertical for the 40 meter
band we can see on the right hand side here looks like this if you're interested in a 3d far field
plot that's our vertical and uh normally if my mouse will keep working if we go to five degrees
let's say just some random number five degrees could be ten but i choose five all my models
and then i know if one antenna is better the other because our the long tall shortwave stuff
is coming to us between about three and eight degrees it can be as high as 20 but the most of it
most of the bigger dx like the sort of double hop stuff two three four five thousand mile plus we're
between three be between three uh three and eight degrees so five degrees of horizon it's quite good
you know like a bass line but it's telling me here at the top middle if i hit that button there
that that is 5 minus 5.3 dbi just a number all right don't worry it says minus
minus 5.3 bananas minus 5.3 something all right so this model here is minus 5.3 right
okay what happens then if we take this antenna and make it red in other words we'll tilt our antenna
over to the right 15 degrees well actually we can do that on i think this one here
uh i don't know x axe let's do the y it would tilt the y it will tilt the x axis
15. i haven't tried this i'm hoping it's still going to be on the ground yeah it is it's over
15 degrees so now when we do a calculate and have a look at the plot it'll be slightly different
not much different uh i just need to check which way it's actually gone
let me just rotate it hang on z axis that's it i wanted to rotate it on the x axis
left right okay so if i now calculate it we should see a very slight difference settle
there we are we can see now if i do my elevation at five degrees off horizon that opposite the lean
so the lean is over to our right opposite to the lean we've got it now says at five degrees
uh we've gone from minus five point three to minus four point eight that way and we've gone
from minus five point three to minus six the other way so in other words you would hardly notice it
this is exactly the same as doing this taking that blue line and make it into a red line
now with the magic of post-production and adobe premiere i'm going to take this uh five degrees
and we are sloping which way right so we need to rotate this plot around 15 degrees to the
left which will be the same as raising that dot to there okay so let's just move it to the left now
it now says here that we've got 1.6 dbi and we start off at 5.3 so that's getting on i don't
know seven d that's a lot a 15 degree slope will give you double the power double again and a bit
more in the direction of the slope so i mean if you're trying to get a you've got a property with
a bit of a slope needs to be multiple wavelengths not just it slopes down goes back up and there's
a blooming mountain there i'm talking a long term slope you know for a couple of miles
then you will have a better signal going in the direction of the slope and i've kind of proved it
to you i hope next video is coming up here i will see you on the next one all the best bye for now
huh all right i think we're done there lovely stop recording