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Asimov wrote:
This is a hypothetical question, if one needs to send more power down a line than its capacity can 2 or more lines be paralleled? Is the equivalent characteristic impedance of the combined lines the same as that of a single individual line? Let's say we parallel two pieces of lossless 50 ohm coax such that the voltages at the load (V1 and V2) are equal magnitude and phase. The currents at the load (I1 and I2) will be equal magnitude and phase. For matched line operation, V1/I1 = V2/I2 = 50 ohms. Pload = (V1*I1)+(V2*I2) = 2*(V1*I1) Vload = V1 = V2 Iload = I1 + I2 Rload *for matched line operation* = V1/(I1+I2) = V1/(2*I1). Rload = 1/2(V1/I1) = 50/2 = 25 ohms. So 25 ohms is the equivalent Z0 of two pieces of 50 ohm coax in *parallel*. Conversely, if you use one piece of 50 ohm coax going to the load and one piece of 50 ohm coax coming back from the load to achieve a shielded balanced feedline, the Z0 of that feedline is 2*Z0 = 100 ohms and the two lines are in *series*. -- 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 =---- |
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