Decrement Measurements Pees 
DECREMENT MEASUREMENTS. 
R. R. Ramsey 
In wireless work one of the important measurements is the logarithmic 
decrement of the aerial or decrement, as it is called in wireless. Decrement 
is an indication of the sharpness of the radiating wave. ‘To Jiken radiation 
from a wireless station to the radiation from a light source: a station with a 
low decrement gives a line spectrum of a definite wave length while a large 
decrement means a band spectrum covering a large range of wave lengths. 
It is hard, or next to impossible to tune out a station with a large decrement. 
On this account the U. 8. Government has outlawed stations with decrement 
greater than .2. Another advantage of small decrement is that all the radiated 
energy of the sending station is concentrated on one wave length, while the 
energy is scattered over a broad band when the decrement is large. 
The solution of the differential equation of an oscillating circuit con- 
taining resistance, inductance, and capacity may be put into the form 
I Sipe “sin wt where I, is the initial or maximum value of the current, I is 
the value of the current at any time, t; w, is the angular velocity or 2zn, n 
being the frequency and, «=R/2L, R being the resistance and L the induc- 
tance of the circuit. 
The equation can be represented by the curve of figure 1. 
The amplitudes are: 
Late oe tiga 8 
—— 
Bie mee. dee cor 
Ie=Te7 272 T. Ie — «27 aT 
etc. le Tee 
In aT 
=e 
