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Tideland Signal Corporation

George Ploussios

An antenna comprising a pair of bent monopole elements (a doublet) that are fed in a manner that results in elevation coverage from the horizon to horizon and dual polarization. Two orthogonal bent monopole doublets provide hemispherical coverage with horizontal and vertical polarization. Combining the doublet terminals through a processing circuit will provide polarization diversity and/or angle diversity capability.

Crossed bent monopole doublets

A collinear electronically tunable helical antenna system includes at least one helical antenna coil; a center conductive tube disposed axially through the open center space of the coil, which may contain bias and control lines and feed lines. The antenna coil is short circuited to the center tube near the base of the coil, forming a tunable choke. Sections of the coil are shorted to electrically shorten the coil, thereby tuning the antenna and choke. Each antenna coil is powered via feed lines that emanate from the antenna base and which run through the conductive tube from below the antenna base. Sections of coil may be shorted by a pair of oppositely poled diodes forming a PIN diode switch connected across a section of antenna coil. A bias voltage that controls the switch is supplied to the switch, via bias lines which run within the antenna coil and exit the antenna coil at a point symmetrical between each pair of oppositely poled diodes. The bias voltage is adjusted to permit the PIN diode switch to provide a short circuit across the selected section of coil thus changing the operating frequency of the antenna and choke. No rf current is directly induced in the conductive tube beyond the choke (and open end) of the antenna coil. Additional independently controlled antennas and other devices may therefore be mounted, without mutual interference, along the conductive tube.

Electronically tuned helix radiator choke

A resonant helical antenna capable of being tuned electronically over a broad range of frequencies. The helical turns of the radiating portion of the antenna are formed of tubular material which may be in the form of a single length of tubing or may comprise a number of parallel coaxial cables with their outer conductors in electrical contact. The antenna is tuned by a series of oppositely poled pairs of diodes that are connected at spaced points to the radiating coils of the antenna. When the diodes are biased to be conducive, a section of the radiating helix is short-circuited. Bias voltages to control the diodes are provided by leads inside the radiating turns of the helix. Each lead for a pair of diodes emerges at a point electrically balanced between the two spaced points that are connected to the associated diodes. No r-f potential exists between the outer and inner conductor of the radiating runs at the point where the bias lead emerges, so no r-f current flows in the bias lead wires. The antenna may include spaced cpacitance elements and may be in the form of a monopole helical antenna or it may be in the form of a dipole antenna with two oppositely-disposed arms.

Electronically tunable antenna

A tunable helical antenna consists of a central support of dielectric material having a helical channel in the outer surface of the support. This channel, which may be square, rectangular or of other shape in cross-section, is plated with a conductive material such as copper. Biasing coaxial cables for controlling the tuning of the antenna are then placed within the channel and the channel sealed by a conductive cover. The plated surface becomes the helical radiating element of the antenna while the leads enclosed in the channel are isolated from r-f currents which are confined to the outer surface of the helix coating and conductive cover. The helical channel in the support may be formed by machining or the support may be molded with the helical channel as an integral part. Either way, precision control over the channel dimensions is readily attained. Pairs of oppositely-poled diodes are connected to spaced points on the radiating element. The conductivity of the diodes is controlled through the biasing cables to adjust the electrical length of the radiating element. The helical channel in the support may be formed by machining or the support may be molded with the helical channel as an integral part. Either way, precision control over the channel dimensions is readily attained.

Method and construction of helical antenna

An S-band antenna with a body having an inner circular tube and a coaxial outer circular tube in which the circumference of the outer tube is one wave length of S-band radar. A plurality of pairs of axially elongated slots are provided in the outer tube in which the slots of each pair are diametrically opposed to each other. Adjacent pairs of slots are axially displaced from each other a distance of one-half wave length. The pairs of slots are rotationally offset at an angle equal to 360/N where N is the number of pairs. A dielectric cover is provided around the outer tube.

S-band coaxial slot array antenna

The invention is embodied in a waveguide polarizer of the kind arranged to alter the propagation modes of an incident wave to produce elliptical or circular polarization. The phase shift is produced by the simultaneous use of dimensional perturbation and dielectric loading distributed along a waveguide section. Embodiments are illustrated using square, circular and crossed waveguide sections. The use of relatively light, symmetrical and continuous loading provides improved performance over that which can be attained by discrete element phase shifters or those that make use of only a single kind of loading.

Waveguide polarizer having conductive and dielectric loading slabs to

The invention comprises an antenna capable of effective operation at a number of different frequencies, not necessarily harmonically related, that may be separated in frequency by as little as twenty-five percent. The elements of the antenna are decoupled by loaded coaxial chokes that form part of the active portion of the antenna at the resonant frequency of the chokes. The chokes are loaded with a solid dielectric insert dimensioned so that the inner surface of the shell of the choke and the outer surface of the conductor extending through the choke form a quarter wave shorted transmission line to produce an infinite impedance at the open end of the choke. The chokes may be arranged in series, parallel or series-parallel configurations.

Multi-frequency antenna employing tuned sleeve chokes

An antenna for transmitting or receiving, for limited fine scan or wide angle scan, or for producing multiple beams has a plurality antenna radiators or receivers (apertures) in a linear array, coupled to a smaller plurality of antenna networks so that many of the antenna apertures are coupled to two of the networks and the networks are all coupled to a common transmission line. For a spatial scanning system, each network is coupled to the common transmission line through a variable phase shifter so that the radiation patterns of the apertures combine to define a beacon of predetermined fine pointing direction that can be used to spatially sweep a sector by varying the phase shifters according to a predetermined schedule. Furthermore, by shifting the point of feed to the networks, the pointing direction is caused to switch in relatively large steps, from one sector to another sector.

Growing community of inventors

Andover, MA, United States of America

George Ploussios