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N9OGL: Exceeding the Part 15 EM limitation for fun and profit
Stagger Lee wrote:
[snip] 2. The power density is related to the electric field and the impedance of free space (120*Pi) by the formula Pd = e^2 / (120*Pi). [snip] Thanks for the reminder on the calculations. Funny but a couple of my younger colleagues who think themselves quite the electronics men still do not think 'space' has an impedance. There is nothing there, after all.. That is what too much PCB layout/CAD work wioll do to one. hehe PJ |
N9OGL: Exceeding the Part 15 EM limitation for fun and profit
Stagger Lee wrote: On 15 Aug 2006 19:40:07 -0700, N9OGL wrote: The power in wattage and the electrical field are not related because a power output in wattage can produce different fields depending on lengh of coax, antenna, antenna height...and your friends in the Office of You can't get around physics, Todd. The power density is directly related to the electric field through an Ohm's law type of relationship, expressed as the square of the r.m.s value of e, divided by the impedance of free space. Once you know the power density, it is a matter of summing that power density over the radiation pattern of the antenna to figure out the total radiated power. Therefore, there *is* a relationship between radiated power and field strength. In the case of an isotropic radiator, the relationship between radiated power and field strength is easy to calculate, and it provides one with a limiting case which can act as a guideline. engineering and technology at the FCC will tell you that. The antenna I'm using is a very imefficient antenna, in fact the signal is acually I'm not interested in your rationalizations, Todd, because I'm not the one who is at risk. In this real world, your power output is about five orders of magnitude larger than the power theoretically needed to produce the maximum allowed electric field. To me, that would be a cause for great concern. If you want to risk an FCC enforcement action against you, be my guest. ==================== God said, "div D = rho, div B = 0, curl E = -@B/@t, curl H = J + @D/@t," and then there was light. I would really suggest you read the FCC Office of Engineering and technology bulletin on PART 15, it OET Bulletin 63 http://www.fcc.gov/Bureaus/Engineeri...3/oet63rev.pdf expecially page 29 which states: What is the relationship between "microvolts per meter" and Watts? Watts are the units used to describe the amount of power generated by a transmitter. Microvolts per meter (µV/m) are the units used to describe the strength of an electric field created by the operation of a transmitter. A particular transmitter that generates a constant level of power (Watts) can produce electric fields of different strengths (µV/m) depending on, among other things, the type of transmission line and antenna connected to it. Because it is the electric field that causes interference to authorized radio communications, and since a particular electric field strength does not directly correspond to a particular level of transmitter power, most of the Part 15 emission limits are specified in field strength. So logically if you use a ineffecient antenna and ****ty coax then you can create a low enough field....I'm tell you right now, I Have a field strength meter that reads microvolts, and I check the field ever morning, at it's not at no 30 meters either, it's around 17.5 meters and the electrical field is 1,0000 uV ...So believe what the hell you want I check it every morning and it's 1,000 uV @17.5 meters and at 30 meters it's 0. I would also point out I come from a long line of electricians (my father, my grandfather and my great grandfather) and THEY will back me up. |
N9OGL: Exceeding the Part 15 EM limitation for fun and profit
In article ,
patrick jankowiak wrote: Stagger Lee wrote: [snip] 2. The power density is related to the electric field and the impedance of free space (120*Pi) by the formula Pd = e^2 / (120*Pi). [snip] Thanks for the reminder on the calculations. Funny but a couple of my younger colleagues who think themselves quite the electronics men still do not think 'space' has an impedance. There is nothing there, after all.. That is what too much PCB layout/CAD work wioll do to one. hehe No this is what our educational system does to EE's. PCB layout and CAD work will bring them back to reality. -- Telamon Ventura, California |
N9OGL: Exceeding the Part 15 EM limitation for fun and profit
No such thing as empty Space in Space,the Universe.Every nook and cranny
in Space is full of things,even Dark Matter.Dark Matter (invisible to the eye Matter) is mostly what Space is made of. cuhulin |
N9OGL: Exceeding the Part 15 EM limitation for fun and profit
patrick jankowiak wrote: Stagger Lee wrote: [snip] 2. The power density is related to the electric field and the impedance of free space (120*Pi) by the formula Pd = e^2 / (120*Pi). [snip] Thanks for the reminder on the calculations. Funny but a couple of my younger colleagues who think themselves quite the electronics men still do not think 'space' has an impedance. There is nothing there, after all.. That is what too much PCB layout/CAD work wioll do to one. hehe Too Bad Saggytits had to cut and paste the "calculations", he didn't know them himself. The only space Saggytits knows about is the one between his dumbo ears. |
N9OGL: Exceeding the Part 15 EM limitation for fun and profit
"Not Cocksucker Lloyd" wrote in message ups.com... patrick jankowiak wrote: Stagger Lee wrote: [snip] 2. The power density is related to the electric field and the impedance of free space (120*Pi) by the formula Pd = e^2 / (120*Pi). [snip] Thanks for the reminder on the calculations. Funny but a couple of my younger colleagues who think themselves quite the electronics men still do not think 'space' has an impedance. There is nothing there, after all.. That is what too much PCB layout/CAD work wioll do to one. hehe Too Bad Saggytits had to cut and paste the "calculations", he didn't know them himself. The only space Saggytits knows about is the one between his dumbo ears. That is why we always register for Pwofessow Woger's classes on negative VSWR and especially his classes on RMS voltage. Pwofessow Woger has perfect attendance at ARES meetings in his area. Herb |
N9OGL: Exceeding the Part 15 EM limitation for fun and profit
Herb wrote: "Not Cocksucker Lloyd" wrote in message ups.com... patrick jankowiak wrote: Stagger Lee wrote: [snip] 2. The power density is related to the electric field and the impedance of free space (120*Pi) by the formula Pd = e^2 / (120*Pi). [snip] Thanks for the reminder on the calculations. Funny but a couple of my younger colleagues who think themselves quite the electronics men still do not think 'space' has an impedance. There is nothing there, after all.. That is what too much PCB layout/CAD work wioll do to one. hehe Too Bad Saggytits had to cut and paste the "calculations", he didn't know them himself. The only space Saggytits knows about is the one between his dumbo ears. That is why we always register for Pwofessow Woger's classes on negative VSWR and especially his classes on RMS voltage. Yet he didn't have to cut and paste from another website and add a few comments so it looks like he wrote the whole thing like you did. Tell us again how Eric Clapton wrote "Layla" for your ex streetwalker wife instead of George Harrison's wife, stupid. Pwofessow Woger has perfect attendance at ARES meetings in his area. So do you hiding behind your hideous ex streetwalker wife, lisping Davey. |
N9OGL: Exceeding the Part 15 EM limitation for fun and profit
On 16 Aug 2006 19:40:03 -0700, N9OGL wrote:
: : I would really suggest you read the FCC Office of Engineering and : technology bulletin on PART 15, it OET Bulletin 63 : http://www.fcc.gov/Bureaus/Engineeri...3/oet63rev.pdf : expecially page 29 which states: : : : What is the relationship between "microvolts per meter" and Watts? : : Watts are the units used to describe the amount of power generated by a : transmitter. Microvolts per meter (µV/m) are the units used to : describe the strength of an electric field created by the operation of : a transmitter. A particular transmitter that generates a constant level : of power (Watts) can produce electric fields of different strengths : (µV/m) depending on, among other things, the type of transmission line : and antenna [snip] Todd, there isn't a law you can quote which governs physics. You can't repeal the law of gravity, and you can't logically state that transmitter power and electric field strength are independent of one another. Think about it: That idea doesn't even make sense. : So logically if you use a ineffecient antenna and ****ty coax then you : can create a low enough field....I'm tell you right now, I Have a field : strength meter that reads microvolts, and I check the field ever : morning, at it's not at no 30 meters either, it's around 17.5 meters Do you know the difference between the far and near fields? Are you aware that an ordinary field strength meter can give you wildly incorrect results when it is placed in the near field of an antenna? Most engineers would tell you that you have to be at least five wavelengths away from the antenna (and preferably ten) before you are out of the influence of the near field. At 33 MHz, the wavelength is roughly nine meters; therefore, your meter is in the near field of the antenna, and all bets are off. : and the electrical field is 1,0000 uV ...So believe what the hell you : want I check it every morning and it's 1,000 uV @17.5 meters and at 30 : meters it's 0. I would also point out I come from a long line of : electricians (my father, my grandfather and my great grandfather) and : THEY will back me up. Sigh. That's what we need: Electricians who never even heard of free space impedance. ==================== God said, "div D = rho, div B = 0, curl E = -@B/@t, curl H = J + @D/@t," and then there was light. |
Cease desist and grow up
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