New answers tagged propagation
5
Rather than just answer your question, I'll show you how to answer it yourself.
VOACAP is a good tool for all kinds of HF propagation questions. Entering your location and the location of the beacon into the point-to-point predictions tool, with parameters set to CW, 100 W, dipoles at 33 feet, and "Residential" noise, clicking on "Prop Charts&...
6
140 miles is too far away on 20m for groundwave propagation and the "skip" zone or first hop distance, given 20m's general DX capabilities, is much longer than 140 miles. So, I wouldn't expect to hear it "without issue". However, when you're tuned to 14.100, you should be able to copy other beacons in the rotation, if your antenna works.
0
In my situation, do I have to use the second formula to find near-field reactive region boundary?
The choice between the two equations you provide is determined by if the antenna is "electromagnetically short", so it isn't about if it is "very short" from a human's perspective of short, but rather how its length compares to the ...
1
Question 1 : Do the EM waves travel by creating disturbances in the air particles such as compression and rarefaction?
The answer is no. Electromagnetic propagation is not dependent on air, unlike sound waves. It can travel in free space. That being said, electrically or magnetically charged air particles, and Earth's magnetosphere can alter the trajectory (...
3
Question 2 & 3 not fully answered...
You probably actually are within line of sight of the FM transmitter. Broadcast transmitter antennas are typically placed on high towers specifically so that more people will be within line of sight of the tower. Of course, you may not actually be able to "see" the tower because of atmospheric attenuation ...
1
This problem is very easy to model with any MOM tool, like EZNEC. E and H fields can be calculated using Near Field grid. Even better, exact power transfer from Tx to Rx antenna can be modeled. Modeling should include both Tx and Rx antenna, including Rx antenna termination resistance. Ratio of transmitted power and dissipation on Rx termination resistor ...
4
Radio waves (such as broadcast AM and FM) can travel through a vacuum (thus do not require air). They are electro-magnetic (or EM) waves, the same as light waves (from the sun and stars, etc.), that can travel through space, but at a vastly lower frequency.
The radius these EM waves can travel (unless blocked or absorbed) is the radius of the universe; but ...
Top 50 recent answers are included
