WAVEGUIDE TRANSMISSION 315 



ing on its return journey. This time, the resultant electric intensity would 

 oscillate between limits of plus or minus 2E, and the resultant magnetic 

 intensity would be zero at all times. To this observer then, this quarter-wave 

 point on the Une would have many of the characteristics of the interior of 

 a condenser charged by an alternating voltage. 



If our observer were to move another one-eighth wave farther along the 

 line, he would note that the resultant electric and magnetic forces would 

 again be equal. Proceeding on to a point one-half wavelength from the metal 

 reflector, he would observe that, at the time crests (maximum positive in- 

 tensity) were passing on their way toward the reflector, hollows would be 

 returning, and accordingly upon examining the resultant electric intensity 

 he would find it to be zero at all times, whereas the corresponding magnetic 

 intensity would be oscillating between limits of plus or minus 2H. At this 

 point along the line, he would be unable to distinguish his electrical environ- 

 ment from that prevailing at the metal boundary. The half-wave line, there- 

 fore, has had the effect of translating the metal barrier to another point in 

 space a half wave removed. 



If the observer were to continue still farther along the line, he would 

 pass, alternately, points where the resultant electric force is zero and other 

 points where the resultant magnetic force is zero. It is important to note 

 that at points in a standing wave where the magnetic force is a maximum, 

 the electric force is a minimum and at points where the electric force is a 

 maximum, the corresponding magnetic force is a minimum. It is customary 

 to call the points of minimum E (or H) "mins," though the term node is 

 sometimes substituted. Points of maximum E (or H) are known as "maxs" 

 with the term loop as its alternative. If the observer were to measure current 

 and voltage along the line, he would find that points of maximum voltage 

 correspond to maximum E and that points of maximum current correspond 

 to maximum H. 



An examination of the energy associated with the incident and reflected 

 waves shows that, except for minor losses not to be considered here, there 

 is as much energy led away from the reflector as is led up to the reflector, 

 and that there is associated with the standing wave a stored or resident 

 energy. The regular arrangement of nodes and loops along a standing wave 

 with minima at half-wave intervals is a very important characteristic, for 

 such points may be located very accurately experimentally, and accordingly 

 wavelength may be measured with considerable precision. 



If, instead of terminating the wire line in a large conducting plane as- 

 sumed previously, it is terminated in a relatively thin cross bar as shown in 

 Fig. 6.2-6, the reflection will assume a somewhat more complicated form. 

 First of all, the thhi cross bar will intercept, initially at least, only a portion 

 of the total wave front. The i)articular lines of force arriving along a plane 



