Think about it this way If you are in the dark in your back yard
and you shine a high powerful flashlight at the forest you will
light up the forest, but if you shine a little penlight at the
same forest you won't see much, and with that said if you stand
on a ladder and shine the penlight down you can then go just
a little farther because of height and then you can concentrate
the beam on objects and yes get out farther, but still only so far.
This is exactly what we are doing here, so think about a 5-watt CB
it travels to the next town because of the line of site,
because it has just enough wattage to make it by the line of sight...
Most cb'ers want tall towers and never would put their antennas on the ground use a milliwatt and say yep that's a great idea... (SAID NO ONE EVER).
Now let's use a milliwatt CB and try to talk to the same town
and they will not hear you
because that milliwatt transmitter will not bounce off the atmosphere
it won't get to the next town and its restricted so much only
line of site and height allow it to reach farther until diminishing
returns like the penlight on top the latter
it can only go so far...
You can build a reflector for your antenna or a radial field etc
but in the end, height always makes might and using milliwatts
you want to be up in the air free of trees buildings and objects
that absorb your milliwatt and waste it, Try 30-40-50ft and see if
your not twice as far as you were at ground or at 10ft etc.
The key is to stay away from objects esp houses, roofs, buildings,
trees, and get up into free space and don't ground it rather instead
use the audio line and the voltage lines to the transmitter as your safety
ground here's a device I use which each line + - Audio in etc has a
terminal grounded so if static or God forbid you take a nearby strike
etc this will dissipate before it enters the studio.
AS-8SP - Eight terminal 65 V Surge suppressor for control lines and rotators
- Brand: Array Solutions
- Product Code: AS-8SP
- Availability: In Stock
-
$89.00
safety ground for data utility cables for lightning protection...
All i am saying is we have been doing it wrong for a long time and need to rethink this whole idea. we are not mega stations using mega efficient antennas we are microwatt peanut whistles and our only true friend is the line of sight... Let me know your thoughts.
Joe the radio dood
lol
I see no one has responded to my theory of line of sight is all we are really doing here. unless you feel ground radials can help a 100 milliwatt walkie talkie I must have made my point serve game and match for the win...
Well, you are comparing apples to oranges. Wavelength has a lot to do with line of sight propagation and 27 mHz is a much shorter wavelength than the AM broadcast band.
As for radials, yes at BCB frequencies radials will make a big difference. A CB walkie or 2 meter walkie needs very little again due to shorter wavelength.
Seems our MW Part 15 range increases with height but when analysed it's generally due to some form of long wire becoming part of the anenna system either by design or accident.
I think the resident expert engineers will chime in on this.
The line-of-sight behavior of radio waves is dependent on the frequency (wavelength). Higher frequencies are more affected by the line-of-sight phenomena.
An example of this is reception of Siruis/XM radio vs. FM radio. Sirius/XM broadcasts at 2.3 GHz (13 cm wavelength). FM radio broadcasts at 88 to 108 MHz (about 3 meter wavelength). This means that Sirius/XM frequencies and reception are more affected by smaller objects (leaves, trees, etc). If you are traveling through a densly wooded area, your Sirius/XM reception may be lost but your FM reception is fine (even though the Siruis/XM transmitter and antenna is higher up).
The AM broadcast signals at a wavelength of 600 meters to 200 meters are affected only by very large objects (e.g. mountains). Trees and houses are essentially invisible at those AM frequencies. Antenna height is irrelevent.
My correction here's the ground wave link.. a lot like a line of sight but lower freq involved.
Non-line-of-sight (NLOS) and near-line-of-sight are radio transmissions across a path that is partially obstructed, usually by a physical object in the innermost Fresnel zone. Many types of radio transmissions depend, to varying degrees, on line of sight(LOS) between the transmitter and receiver.
http://www.rfwireless-world.com/Terminology/wireless-propagation-modes.html
We are using 100mw not 5 watts, not 50 not 500 5000 or 50000 so using 100mw you have a basic walkie-talkie at 1.6mhz. A perfect example is, I have the Hamilton mounted on a 12ft pole I could get out roughly 3/4 of my town now I have it up at 30 feet and it covers the entire town now.
So by your theory, you are taking into account that skywave would be involved at 1.6mhz at 100 MW there's not enough signal like a walkie talkie basically also cannot reach the town next door. With our 9' 8" antennas and 100 MW line of sight is all we have... A good example of this are the silos north of this location as soon as we drive in front of them the radio signal is being routed around them using ground wave and nothing else...