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RF and the ionosphere
Several months ago we had a thread about RF going through the
ionosphre if the angle was accute enough. IE 90 degrees. I wrote the fine people at www.spacew.com/proplab. This is my original question to them and their response. I would suggest that anyone who is interested in this subject download and read thier manual, it is educational. Now if I just had a spare $150 kicking about...... Terry -------------------------------- This may be a silly question, but does any RF penetrate the ionosphere even at the MUF? Can you suggest any online links for info on thsi subject? Sorry for not responding earlier on this. Assuming we are speaking strictly of RF that has a known trajectory (elevation angle with respect to the ionospheric layer), and we aren't including effects of reflected/scattered RF energy that may reach the ionosphere at an angle different from the primary RF energy, then the answer is no - no RF energy penetrates the ionosphere, even at the MUF - provided all the RF energy is below the critical reflection frequency of the ionospheric layer in question. If a 20 MHz signal is omnidirectionally transmitted, there WILL be RF energy penetration at near vertical incidence because that frequency will exceed the critical plasma frequency of the F-layer (even during the day). We don't have any specific links to sites on the Internet for this particular subject. Our Proplab-Pro manual is available online (a link under www.spacew.com/proplab) that includes a fairly comprehensive discussion concerning ray reflection and may help (it's a PDF document). -------------------------- |
Screw the 150$ !!!
Download it here for FREE! http://solar.spacew.com/solar/skyman.html wrote in message oups.com... Several months ago we had a thread about RF going through the ionosphre if the angle was accute enough. IE 90 degrees. I wrote the fine people at www.spacew.com/proplab. This is my original question to them and their response. I would suggest that anyone who is interested in this subject download and read thier manual, it is educational. Now if I just had a spare $150 kicking about...... Terry -------------------------------- This may be a silly question, but does any RF penetrate the ionosphere even at the MUF? Can you suggest any online links for info on thsi subject? Sorry for not responding earlier on this. Assuming we are speaking strictly of RF that has a known trajectory (elevation angle with respect to the ionospheric layer), and we aren't including effects of reflected/scattered RF energy that may reach the ionosphere at an angle different from the primary RF energy, then the answer is no - no RF energy penetrates the ionosphere, even at the MUF - provided all the RF energy is below the critical reflection frequency of the ionospheric layer in question. If a 20 MHz signal is omnidirectionally transmitted, there WILL be RF energy penetration at near vertical incidence because that frequency will exceed the critical plasma frequency of the F-layer (even during the day). We don't have any specific links to sites on the Internet for this particular subject. Our Proplab-Pro manual is available online (a link under www.spacew.com/proplab) that includes a fairly comprehensive discussion concerning ray reflection and may help (it's a PDF document). -------------------------- |
Jack wrote:
Screw the 150$ !!! Download it here for FREE! http://solar.spacew.com/solar/ skyman.html ------------------------------ I meant that I wish I had 150$ for the actual program. It looks interesting. Terry |
Gimme a day or so and I may have it for you??
Jack wrote in message oups.com... Jack wrote: Screw the 150$ !!! Download it here for FREE! http://solar.spacew.com/solar/ skyman.html ------------------------------ I meant that I wish I had 150$ for the actual program. It looks interesting. Terry |
HEDAASH wrote:
Gentlemen, It all depends on: the time of day; the critical angle; and the frequency of interest. The best thing is to get one of the free propagation programs, and play with it to fully understand the implications of the three variables working together. In reality, unless you are in the business of SIGINT, or going for all DX awards, it is of little use to most SWL or operators. Joe ------------------------- In the orignal thread we we wondering/debating what, if any, RF penetrated the ionosphere. Not all that practical a musing as none of us are likely to be on the far side of the ionosphere. I had mentioned that I remembered reading that at all frequencies some RF made it through to free space. I was attempting to correct me error. A good understanding of propagation does help snag the rare ones. Terry |
" wrote: wrote: Several months ago we had a thread about RF going through the ionosphre if the angle was accute enough. IE 90 degrees. I wrote the fine people at www.spacew.com/proplab. This is my original question to them and their response. I would suggest that anyone who is interested in this subject download and read thier manual, it is educational. Now if I just had a spare $150 kicking about...... Terry -------------------------------- This may be a silly question, but does any RF penetrate the ionosphere even at the MUF? Can you suggest any online links for info on thsi subject? Sorry for not responding earlier on this. Assuming we are speaking strictly of RF that has a known trajectory (elevation angle with respect to the ionospheric layer), and we aren't including effects of reflected/scattered RF energy that may reach the ionosphere at an angle different from the primary RF energy, then the answer is no - no RF energy penetrates the ionosphere, even at the MUF - provided all the RF energy is below the critical reflection frequency of the ionospheric layer in question. If a 20 MHz signal is omnidirectionally transmitted, there WILL be RF energy penetration at near vertical incidence because that frequency will exceed the critical plasma frequency of the F-layer (even during the day). We don't have any specific links to sites on the Internet for this particular subject. Our Proplab-Pro manual is available online (a link under www.spacew.com/proplab) that includes a fairly comprehensive discussion concerning ray reflection and may help (it's a PDF document). -------------------------- Gentlemen, It all depends on: the time of day; the critical angle; and the frequency of interest. The best thing is to get one of the free propagation programs, and play with it to fully understand the implications of the three variables working together. In reality, unless you are in the business of SIGINT, or going for all DX awards, it is of little use to most SWL or operators. Easier just to use your receiver and ears and perhaps check a forecast or two. http://www.n3kl.org/ dxAce Michigan USA |
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