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Curious about the I.R.E. Standard Dummy Antenna
"H. P. Friedrichs" wrote in message news:1YOdna1FqcOin2DZnZ2dnUVZ_tCdnZ2d@velocitywest .com... I am interested in the origins and purpose of the "IRE (Institute of Radio Engineers) Standard Dummy Antenna," as used during the alignment of radio receivers. I first came across this circuit in some old Hallicrafter's documentation, which described the alignment of a particular radio. The "IRE Standard Dummy Antenna" consists of four components--- a 200pf cap in series with a 20 uH inductor, which links the signal generator to the receiver's antenna input. A 400 pF cap in series with a 400 ohm resistor is connected in parallel with (shunts)the inductor. I gather that this circuit models a wire antenna of some type. Is this true? What is the import of the component values and how were they arrived at? I modeled the circuit in Spice and graphed the transfer and impedance curves but it is not entirely clear to me what benefit there is to using this circuit. I've also Googled this and found some references here and there, but nothing explains the "why" of it. Is there anyone who can shed light on this? 73 Pete AC7ZL Yes, the dummy antenna models a wire resonant at 2.something Mc. I suppose that was taken to be more or less typical of the receiver antennas of the 30s. The dummy antenna's most important use is as a standardized load for measuring receiver sensitivity. Terman's Radio Engineer's Handbook has a few paragraphs on this. If you're just adjusting the RF coils, peaking them up on the antenna normally used would be as good or better. Any sort of loose coupling between the generator and RF coils will get you in the ballpark with most radios. Frank Dresser |
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