A 60-FOOT PARABOLIC ANTENNA FOR PROPAGATION STUDIES 1205 



The standard method of measuring the gain of a microwave antenna 

 is to compare the signal received from the antenna to that from another 

 antenna whose gain is accurately known. A pyramidal horn of about 20 

 db gain is usually used as the standard. Such horns are readily available 

 at 4 kmc and 9.4 kmc, and, in principle, also at 460 inc. Under the 

 present set up, however, the physical dimensions of the standard horn 

 were limited by the necessity of raising the horn on a carriage attached 

 to the 64-foot tower. The largest horn that could be so mounted had an 

 aperture of 4 feet X 4 feet, or 1.8X on a side at 460 mc. Since the gain of 

 a horn of this small aperture size cannot be accurately calculated by the 

 usual formulas a scale model was made and tested at 4 kmc. The result 

 of this test showed that the actual horn gain was 15.05 db, which is 

 about 0.4 db more than the calculated gain. 



A typical gain measurement on the 60-foot paraboloid was thus made 

 as follows: 



1. The feed position and antenna orientation were adjusted to obtain 

 maximum received signal level. 



Fig. 8 — Position of height run tower during gain measurements. 



