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#11
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On Wed, 06 Apr 2005 10:51:44 -0700, Wes Stewart
wrote: I'm really surprised that "The 'ole Metrologist", Richard Clark, didn't already jump in with this. Is this dance a "mixer?" |
#12
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Wes Stewart wrote:
wrote: That's interesting! That part regarding change of "density" How does one determine the density changes in various parts of a radiation pattern? Jeeze. You use an rf densiometer of course. To be fair, Art did have a smiley face farther down. The units of the Poynting Vector are e.g. joules/sec/meter^2. That's a power density and is the same as "irradiance" in the field of optics. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#13
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Wes Stewart wrote:
Roy Lewallen wrote: An alternate method is to put some of the RF into a water-tight and RF-tight box -- a great application for one of those ammo boxes left over from survivalist exercises or just plinkin'. Drop the box into a tub of water and see how much the water level rises. Then open the box and let the RF out. (Be sure to wear safety glasses. A shielded cod piece isn't a bad idea either.) Repeat the measurement. You can then calculate the power density from the difference between the amounts the water level rises. A takeoff on this method would be to leave the rf in the box and measure the temperature rise of the water. This eliminates the need for the cod piece. I'm really surprised that "The 'ole Metrologist", Richard Clark, didn't already jump in with this. Yes, but the question from quantum physics is: Is the RF dead or alive before you open the box? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#14
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"corse, what do you do when your Isotropic antenna exibits gain over
your antenna? Does this mean if you stack 2 Isotropics, you have a gain array ?? ![]() Roy Lewallen wrote: Wes Stewart wrote: On Wed, 06 Apr 2005 00:37:34 GMT, " wrote: That's interesting! That part regarding change of "density" How does one determine the density changes in various parts of a radiation pattern? Jeeze. You use an rf densiometer of course. An alternate method is to put some of the RF into a water-tight and RF-tight box -- a great application for one of those ammo boxes left over from survivalist exercises or just plinkin'. Drop the box into a tub of water and see how much the water level rises. Then open the box and let the RF out. (Be sure to wear safety glasses. A shielded cod piece isn't a bad idea either.) Repeat the measurement. You can then calculate the power density from the difference between the amounts the water level rises. Roy Lewallen, W7EL (a little late this year, but hey, better late than never) |
#15
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Jik, NN7K wrote:
"Does this mean if you stack 2 isotropics, you have a gain array?" This thread has provided many laughs. I`m sorry to to insert a serious, on my part, posting, but it may bring a chuckle too. Terman writes on page 874 of his 1955 edition: "The spacing of the individual antennas in a broadside array has only a secondary effect upon the directional characteristics of the array provided the spacing is not too great. Thus, when the individual antennas are isotropic radiators, vbarying the spacing from very small values up to 3 lambda/4 affects only the minor lobe structure, as shown in Fig. 23-11 b." Best regards, Richard Harrison, KB5WZI |
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