Abstract: A low profile slot antenna is provided which includes first and second oppositely disposed metallic plates with a dielectric layer disposed therebetween. An array of horizontal and vertical radiating elements are formed in the first metallic plate. An array of horizontal coupling slots and an array of vertical coupling slots are formed in the second metallic plate. The antenna further includes a planar feed network electrically coupled to the coupling slots. The feed network is connected to a conductive waveguide tube located at the central portion of the antenna. Orthogonal probes couple the waveguide tube to a transceiver. Accordingly, the slot antenna may operate to transmit and receive linearly polarized energy. The antenna may further include a polarization converter for converting between linear and circular polarization so as to allow for antenna operation with single or dual circular polarization energy.

Abstract: A track-seeking and track-following servo encodement and detection system employs a servo pattern using a reference signal and control signals, the control signals having an orthogonal phase relationship to each other by cyclically revolving in phase by 90.degree., 180.degree., 270.degree., and repeating this pattern every four tracks.

Abstract: Phenol or a phenol related compound is detected in an electrochemical cell comprising a cathodic compartment containing a cathode in an electrolyte solution containing ferrocyanide ion and an anodic compartment containing an anode formed by coating a gel containing a phenol or phenol related compound oxidizing enzyme onto the conductive substrate of said anode immersed into an electrolyte solution containing ferrocyanide ion into which pure oxygen is passed; means for maintaining a conductive relationship between anodic and cathodic compartments; and means connected to said anode and cathode for measuring the potential of the oxidation of said phenol or related compound.