A high-resolution rapid-scan antenna

Abstract

An electronically scanned antenna array is described . It consists of a broadside array of seven Yagi elements spaced 1.4 wavelengths apart. Each element antenn a is connected to a preamplifier-converter. Each conver ter is connected to a local oscillator differing by 20 cis from that connected to the converter for the adj acent clement. All oscillators are locked in phase. The converter outputs are co nnected to a common IF amplifi er. This arrangement produces a 5.8-degree-wide beam swept over a 41. 8-degree azimuth sector at a rate of 20 scans per second. The system operates at 40.92 Mc/s. The output of the system is displayed on an oscill oscope, and data on the direction of arrival and character of a distant VHF signal are presented vis ually.Sample reco rds of signal compone nts propagated by ionospheric scatter , meteor trail r efl ections, and sporadic-E layer are cited .

Measurement of elevation angles of h.f. waves

“…If we may assume that the mode-elevation angles remain constant, or nearly constant, over several frames, but that the relative amplitudes and phases of the modes vary from frame to frame, a very simple mathematical technique may be used to find the angles. Suppose that a linear combination of the aerial signals can be found, such that, for each frame, and a,S, cos </ >, • = 0 a,Sj sin <f>; = 0 (9) (10) Physically, the a, represent amplitude taper, and the linear combination of signals represents the output of an array network combining the six aerials with appropriate taper. Comparison of eqns.…”