Abstract: A bolus that communicates with an external transceiver by way of radio waves produced by an electrically small H-antenna is described. The electrically small H-antenna is connected to a conductive cylindrical antenna that houses a battery and chipset that includes a transceiver, identification information and at least one sensor. The H-antenna and the conductive cylindrical antenna are arranged so that electrical currents that produce the radio waves are essentially always aligned to work together. The bolus is essentially a hermetically sealed capsule containing the antennas that is meant to be ingested by a cow or other ruminant animal. The bolus is configured to transmit radio waves in essentially an omnidirectional pattern more efficiently when the boluses inside of a cow stomach than when the boluses outside of the cow.

Abstract: A bolus that communicates with an external transceiver by way of radio waves produced by an electrically small H-antenna is described. The electrically small H-antenna is connected to a conductive cylindrical antenna that houses a battery and chipset that includes a transceiver, identification information and at least one sensor. The H-antenna and the conductive cylindrical antenna are arranged so that electrical currents that produce the radio waves are essentially always aligned to work together. The bolus is essentially a hermetically sealed capsule containing the antennas that is meant to be ingested by a cow or other ruminant animal. The bolus is configured to transmit radio waves in essentially an omnidirectional pattern more efficiently when the boluses inside of a cow stomach than when the boluses outside of the cow.

Abstract: A microstrip antenna includes a ground plane element and a radiating element. An elongated trough is formed generally in the middle of the radiating element so as to divide the radiating element into two generally equally-sized portions, and in a manner to extend outward from a bottom surface of the radiating element. The trough includes a first side edge, a second side edge, and a bottom surface. A first radiating portion extends from the first side edge, and a second radiating portion extends from the second side edge. The trough provides an elongated microstrip-size element at the bottom surface of the trough. A relatively thin dielectric layer is provided between the bottom surface of the trough and a corresponding portion of the ground plane element, thereby providing that a microstrip transmission line is formed by the bottom surface of the trough, the thin dielectric layer, and the corresponding portion of the ground plane element.

Abstract: A transmit/receive antenna selectively operates to transmit or receive at one or more of a plurality of different frequencies in the MHz range. A planar transmission line diplexer or multiplexer that is selected from the group microstrip multiplexer diplexer/multiplexer and stripline diplexer/multiplexer connects an input/output port to a plurality of antenna ports that are physically spaced from each other and from the input/output port. One antenna element is connected to each of the antenna ports. The transmission line diplexer/multiplexer includes a plurality of individual microstrip/stripline elements that have a characteristic impedance and a length that are selected such that the transmission line diplexer/multiplexer automatically provides a matched impedance path between a given antenna element and the input/output port when an antenna-matching frequency is received by the given antenna element or when the antenna matching frequency is applied to the input/output port.

Abstract: An antenna is formed from a single sheet of generally planar metal that is cut to provide four geometric antenna shapes that comprise a ground plane element, a two-section shorting element that is defined by two generally parallel fold lines, a radiating element, and an arm that has one end fixed to a generally central portion of the radiating element and has a free end that extends toward a fold line. Folding the metal sheet on the two fold lines positions the radiating element above the ground plane element. A transmit/receive coaxial cable is aligned with a gap that is formed between the two sections of the shorting element. The cable's outer metal sheath is connected to a metal tab, and the metal tab is secured to a surface of the ground plane element. The cable's center conductor is secured to a surface of the radiating element. A radome and its mounting tab complete the antenna assembly.