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#1
October 14th 14, 07:09 PM
posted to rec.radio.amateur.antenna
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Short antenna = reduced power
rickman wrote:
On 10/14/2014 12:58 PM, wrote: rickman wrote: On 10/14/2014 1:21 AM, wrote: rickman wrote: On 10/13/2014 11:45 PM, wrote: snip 9.87 nothing; the expression is unitless, i.e. a pure number without units. In the expression you have a length divided by a length, which cancels into a unitles number. As my old physics professor used to say, always check the units of your answer; the arithmatic may be correct but it is meaningless unless the units are correct. Sample problem: You drove 100 miles and used 5 gallons of gas. What was your mileage? 5 gallons * 100 miles = 500 gallon-miles --- wrong units. 5 gallons / 100 miles = .05 gal/mile --- wrong units. 100 miles / 5 gallons = 20 miles/gal --- correct units and correct answer. I have no idea what you are going on about. Ok, 9.87 is a unitless number. So is 33.043. Now what? Exactly. Since it is a unitless number, it can not be power as claimed. Nor can it be a rule of thumb for power versus antenna length as a full wave antenna does not radiate 4 (39.48/9.87) more power than a 1/2 wave antenna. It is just nonsense. Did you read the OP? He says: "Has in the equation for radiated power the term" He is just giving us a portion of the equation to show the dependence on wavelength vs antenna length. But without the full equation we can't know if there are mitigating factors. And it is utter nonsense. There is NOTHING about a 1 wavelength antenna that is 4 times that of a 1/2 wave antenna, or 16 times than of a 1/4 wave antenna, which is what the expression evaluates to. The part L/LAMBDA is the fractional size of the antenna, and the rest just numbers and I assume you have a calculator of some kind. It has already been shown by others that, neglecting loss, all power is radiated by an antenna no matter what the size. -- Jim Pennino |
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