A field-strength meter and standard radiator for centimetre wavelengths

The paper describes the development of a field-strength meter and standard radiator for operation at a wavelength of about 9 cm. Details are given of a modified form of Wheatstone Bridge which can be calibrated to give direct readings of the power absorbed in a bolometer. The field-strength meter takes the form of an electromagnetic-horn receiver in which the received power is measured by means of a bolometer. It is shown how the gain of such an aerial may be determined experimentally, and how, knowing this gain, the field-strength existing at the aperture of the horn may be found. The range of power measurable by the bolometer used limits the field-strength range of the equipment to 0.1¿50 V/m. The standard radiator consists of the same type of horn as the field-strength meter but with small modifications. A description is given of the application of the two instruments to the determination of the power radiated by a transmitter, and to the estimation of the over-all sensitivity of a receiver.