Kirt's Cogitations™ #137
Mnemonic for VSWR and Return Loss
These original Kirt's Cogitations™ may be reproduced (no more than
5, please) provided proper credit is given to me, Kirt Blattenberger.
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Cog·i·ta·tion [koj-i-tey'-shun] – noun: Concerted thought or
reflection; meditation; contemplation.
Kirt [kert] – proper noun: RF Cafe webmaster.
At 11.44 dB, both "Pi" and "T" attenuators use
equal value resistors for all three branches when source and load terminations are equal. For 50 Ω, the three
resistors are all 28.9 Ω in the "Pi" configuration and 86.6 Ω in the "T." For 75 Ω, the three resistors are all
43.3 Ω in the "Pi" configuration and 127.9 Ω in the "T."
Head Sport aG has a new "smart" tennis racket that you'll get a charge out of - literally. Its yoke (the
y-shaped area between the handle and the head) is constructed with piezoelectric fibers that generate a voltage
when the racket is swung. The converted energy is conditioned and fed to an analog microcircuit and then
retransmitted to fibers along the yoke to stiffen it in select locations to counter vibrations. More control over
and power to the ball is the result. Professional players are testing the racket now. The International Tennis
Federation prohibits the use of batteries in rackets, and this is the ingenuous workaround. Head is also testing a
smart snow ski that modulates the torsional stability of the ski along its length to adapt to snow conditions.