Excitation of magnetostatic backward volume waves

This paper reports a theory for the electromagnetic transduction properties of magnetostatic backward volume waves (MSBVW's). The basic problem treated is that the MSBVW excitation by the most basic electromagnetic transducer, viz., a line-current source. The excitation characteristics of a practical extended transducer in the form of a microstrip are synthesized from the line-current source results. The frequency variation of the radiation resistance and reactance of these transducers is calculated over the entire magnetostatic volume wave (MSVW) spectrum. At the high-frequency end of the spectrum, MSBVW excitation by a microstrip is the strongest and comparable to magnetostatic forward volume wave (MSFVW) excitation obtaining at the opposite (or low-frequency) end of the spectrum. While the line-current source yields significant excitation of higher-order MSBVW's, with a microstrip, because of the array effects associated with the extended geometry of a microstrip in relation to the line-current source, the higher-order modes are strongly suppressed.