Abstract A phase sensing device, indicating RF transmitter antenna resonance with a high degree of accuracy, for use with tuneable antennae operating in a frequency range of 2 - 30 MHz. The device operates by sampling a time varying (RF) voltage and current appearing at the antenna feed point. A sample of the voltage between the antenna terminal and ground is vectorially combined in two ways with the voltages proportional to the antenna input current. In the first combination, the voltage is derived from the current and leads the current by 90*, while in the second combination, it lags the current by 90*. The resultant RF voltages are rectified independently, and the two independent DC voltages obtained are combined or added with opposite polarity. The difference of the two DC voltages is then the output signal of the sensor and since proportional to the phase difference of voltage and current in the antenna is indicative of the resonant condition of a tuneable antenna. The sensing error signal of the present device may then be connected to amplifiers and a servo motor coupled to a tuning reactor attached to the antenna. The device includes a transformer, center tapped to ground substantially eliminating stray capacitive effects, while the overall circuit requires no balancing adjustment because of its inherent symmetry.
A device coupled to an RF antenna for providing a signal indicative of the resonance condition of the antenna comprising: an RF transformer including a toroidal core having a primary winding, and first and second secondary windings coupled thereto; each said first and second secondary windings including an insulated conductor, said conductors being twisted together symmetrically about each other from substantially one end to the other end of said secondary windings; said one end of said first and said other end of said second secondary windings being connected in common and to ground; matched rectifying means coupled to said other end of said first and said one end of said second secondary windings; capacitive voltage dividing means connected between one end of said primary winding and ground; the other end of said primary winding having means for feeding said antenna; means connecting said matched rectifying means to said capacitive voltage dividing means; and DC signal output means coupled to said rectifying means and said capacitance voltage dividing means for receiving a DC signal indicative of the antenna resonance condition.
Claim 2
Independent Claim
179 words
A device coupled to an RF antenna for providing a signal indicative of the resonance condition of the antenna comprising: an RF transformer including a toroidal core having a primary winding, and first and second secondary windings coupled thereto; each said first and second secondary windings including an insulated conductor, said conductors being twisted together symmetrically about each other from substantially one end to the other end of said secondary windings; said one end of said first and said other end of said second secondary windings being connected in common and to ground; matched rectifying means coupled to said other end of said first and said one end of said second secondary windings; capacitive voltage dividing means connected between one end of said primary winding and ground; the other end of said primary winding having means for feeding said antenna; means connecting said matched rectifying means to said capacitive voltage dividing means; and DC signal output means coupled to said rectifying means and said capacitance voltage dividing means for receiving a DC signal indicative of the antenna resonance condition.
Claim 3
Dependent Claim
50 words
A device, as in claim 1, wherein: said rectifying means includes a pair of matched diodes, the cathode of one said diode connected to said one end of said second secondary winding and the anode of the other said diode connected to said other end of said first secondary winding.
Claim 4
Dependent Claim
20 words
A device, as in claim 2, including: an RF choke connected between said matched diodes and said signal output means.