Scanning characteristics of microwave aplanatic lenses

The imaging properties of two types of solid dielectric, circularly symmetric lenses were studied at a wavelength of 1.25 cm. One of these was a wide-angle aplanat proposed some time ago by Martin; the other was a modification of the two-point corrected lens recently discussed by Sternberg. The work was carried out for the purpose of finding their scanning characteristics and to compare their ability to produce good pencil beams of radiation. Measurements disclosed that in these lenses (having focal number of 1.5), a beam, of half-power width , could be scanned up to about of arc from the optical axis by displacement of the source. The presence of astigmatism prevented either lens from being employed for wider scanning angles. In view of this fact, there appears to be little advantage in this case in using the two-point corrected lens over the simple aplanat which can be more easily designed.