The notch aerial and some applications to aircraft radio installations

The results of a theoretical analysis, supported by experimental measurements, show that very efficient aerials having interesting radiation patterns and useful impedance characteristics can be obtained by exciting metallic sheets with notches cut perpendicularly to an edge. If the notch is about ¿/4 deep, wide-bandwidth aerials can be obtained; but the detail of the polar diagram may be quite sensitive to frequency, depending on the shape and size of the sheet. If the notch is small compared with the wavelength, it may still be tuned over a wide frequency band and used as an efficient aerial. Examples are given of the application of these small notches as aircraft aerials.