250 PIERCE. 



PART V. 

 Field Intensities and Summary. 



26. The Electric and Magnetic Intensities at a Distant Point 

 in the Horizontal Plane. — Equation (19) gives the values of the 

 electric and magnetic intensities at a distant point due to the vertical 

 portion of the antenna. If we replace I of that equation by its value 

 in terms of lo from equation (6), and make cos 6 = 0, we have the 

 intensities in the horizontal plane in terms of lo, which is the amplitude 

 of the current at the base of the antenna. This gives 



Ee = Hfi = — cos — (ct — To) 

 cro X 



cos B — cos G 



. ttXo 

 ^^"2X 



- (Ill) 



The quantities outside the square brackets are constant for a given 

 distance Tq and a given amplitude of transmitting current Iq. The 

 relative iniefisities are therefore determined by the factor in the square 

 brackets, which we may designate by 



„ _ cos B — cos G 



~ 7^ ■ (112) 



^^"2X 



Using the values oiB, G, given in equation (20) and the value of 7 in 

 (110), this equation (112) becomes 



/ttXoX ttXo 



cos7(;^r )-cos — 



• X= ^^^^ ?^- (113) 



. TTAo 



^^^2x: 



This quantity X we shall call "The Intensity Factor in the Hori- 

 zontal Plane." It is to be noted that the electric and magnetic 

 intensities in the horizon plane are not effected by radiation from the 

 flat-top; for, by equation (55), the field intensities from the flat-top 

 are zero for z = 0; that is, all over the horizontal plane through the 

 origin. 



