(under subclass 700) Subject matter wherein the active antenna is combined with an adjustable inductance or capacity, distinct and separate from the active antenna, the inductance or capacity providing a reactance which combines with the inherent reactance of the active antenna to establish a resonance in a circuit including the antenna, this resonance being at a frequency other than the natural electrical resonant frequency of the antenna, adjustment of the inductance or capacity changing this resonance.
(1) Note. The inherent reactance includes not only the distributed reactance of the active antenna but also the natural reactance of the antenna due to its location and surroundings, as for example, the capacity relation inherent in the position of the active antenna relative to ground.
(2) Note. Loading under subclass 749 is always combined with an active antenna of an appreciable electrical length, while such an appreciable length is not necessary for classification in this subclass (745). The reactance combined with the active antenna under loading (subclass 749) must be located within the active antenna, at its free end, or immediately contiguous the end of the active antenna closest to the leadin, whereas the adjustable reactance under this subclass (745) is located outside or external to the active antenna.
(3) Note. Adjustable reactance networks which do not tune
the inherent reactance of the antenna are not classified here, but will be found in subclasses 850+, especially subclass 861 where adjustable impedance matching networks are involved.
(4) Note. Antennas combined with tuning networks are classified herein, except where in addition significant transmitter or receiver structure is claimed. For classification of such latter combinations, see Class 455, appropriate subclasses.
(5) Note. Where an adjustable reactance is combined with an active antenna but the combination is for changing the width of the resonant band, classification is not herein but in subclasses 850+ below. For classification herein adjustment of the reactance in such combinations must be for tuning, that is, changing the resonant frequency of the active antenna circuit. (6) Note. The variable reactance may be located at the coupling end of the antenna, or at the end remote from the coupling end to connect the antenna to ground. In the latter case, if the reactance is not adjustable, classification is in subclass 845. See also subclass 750 below for antennas having adjustable reactance intermediate its ends for loading.
SEE OR SEARCH THIS CLASS, SUBCLASS:
722, for antenna having lumped reactance electrical filters between sections of the active antenna.
723, for single electrically long end-fed antennas which are adjustable in length for tuning.
731+, for traveling wave type antennas which may have phasing reactances within the active antenna.
739+, for active antennas having a terminating resistance at the open end.
744, for high frequency type loops having series reactance in the loop.
749+, for antennas having lumped reactance for loading. See also (2) Note above.
850+, for antennas in general with a coupling network or impedance in the leadin which may include adjustable reactances, and particularly subclass 861 for such antennas having an adjustable impedance matching network. See also (3) Note, above.
913, for reflectors or directors combined with an impedance which may have an adjustable reactance for tuning the reflector or director.
SEE OR SEARCH CLASS 333, Wave Transmission Lines and Networks, particularly
167+, for wave filters, and subclasses 219+ for resonators of the distributed parameter type.
334, Tuners, appropriate subclasses for tuned networks for use in radiant energy apparatus and comprising inductance and capacitance elements in circuit arrangement to form a resonant circuit and in which structure is provided for adjusting one or both of these elements for changing the mean resonant frequency of the circuit.
336, Inductor Devices, particularly
130+, and 137+ for variable inductor devices which may be used in adjustable reactance circuits for tuning active antennas.
361, Electricity: Electrical Systems and Devices,
287+, for variable capacitors which may be used in tuning circuits.
