A videography technique to identify electromagnetic modes in oversize waveguides

It is well known that different modes of electromagnetic waves in a waveguide have different attenuation for a waveguide of fixed size. For example, a TE8.1(Transverse Electric in circular guide mode has decreasing attentuation with increasing frequency. This property is shared by all TE0.n modes, and because of this, property some waves have received a good deal of attention for possible long distance propagation of en9r4ykl) and for low ohmic losses in rsonators of microwave and millimeter wave power sources such as gyrotrons.2) One of the major problems in the use of TEOn in circular waveguides arises because it is not the mode of lowest cutoff frequency, and therefore must always be used in a guide capable of propagating a number of modes (known as oversize guides). For the TEo.1 mode in a circular waveguide there are at least four other modes propagating if the TE mode is above cutoff T1, 10.1, TE21). There are few ways to identify the mode of propagation 0.1 in an oversize waveguide, and even to measure the fractional power in each of them.