Abstract: A method of generating a warning signal for a walkie-talkie includes: providing a detector and a timer; using the timer to count time; using the detector to determine whether the strength of a radio frequency (RF) signal which includes a standard CTCSS tone received by the walkie-talkie is larger than a predetermined value; using the detector to determine whether the strength of a RF signal which includes a non-standard CTCSS tone received by the walkie-talkie is larger than the predetermined value; if so, resetting the timer; and issuing a warning signal when the time counted by timer reaches a predetermined time.

Abstract: A method of generating a warning signal for a walkie-talkie includes: providing a detector and a timer; using the timer to count time; using the detector to determine whether the strength of a radio frequency (RF) signal which includes a standard CTCSS tone received by the walkie-talkie is larger than a predetermined value; using the detector to determine whether the strength of a RF signal which includes a non-standard CTCSS tone received by the walkie-talkie is larger than the predetermined value; if so, resetting the timer; and issuing a warning signal when the time counted by timer reaches a predetermined time.

Abstract: A multi-channel feed network includes a common waveguide section (either square or circular) for connection to a satellite antenna for propagating two orthogonal polarizations. The feed network further includes a low pass section connected with the common waveguide, and a high pass section. The low pass section includes a band reject filter (BRF) formed from slots cut to reject higher frequency signals. The high pass section can be a rectangular waveguide functioning to filter low frequency signals. Orthogonal linear polarizations are provided for the high frequency bands by adding additional high pass sections connected by power dividers, and for the low frequency bands by adding a conventional OMT. By using two 90° degree hybrid couplers and two power dividers, a high pass network can be created to support dual circular or linear polarizations. The high pass network can be die cast as an integrated unit to simplify manufacturing.

Abstract: A dual band antenna feed is made with an embedded waveguide structure to enable combining of Ka and Ku band signals without the need for an additional cavity-type filter. The antenna feed includes a Ka and Ku band interface section (22) with two Ka band vertical polarization waveguide sections (31) and (32), and a single Ku band waveguide section (34) which carries both vertical and horizontal polarization Ku band signals. The opposing walls (36-37) of the Ku band waveguide (34) carrying the vertical polarization Ku band signals are transitioned to step down from an input section (40) to successively smaller dimensioned sections (41-44), and then to step back up in successively larger dimensioned sections (45-47) to an output section (48). The two Ka band sections (31-32) are fed into openings in Ku band section.(46), on opposite sides of the opening for the Ku band transition section (45). The output section (48) then provides a combined Ka band vertical and Ku band horizontal and vertical signals.

Abstract: A multi-channel feed network includes a main waveguide section (either square or circular) for connection to a satellite antenna for propagating two orthogonal polarizations. The feed network further includes a low pass section connected on axis with the main waveguide, the low pass section having the same cross section as the main waveguide, and a high pass section also connected perpendicular to the main waveguide. The low pass section includes a band reject filter (BRF) formed from slots cut to reject higher frequency signals. The high pass section can be a rectangular waveguide which functions to filter low frequency signals. The feed network can be configured to support a number of different polarizations. Orthogonal linear polarizations are provided for the high frequency bands by adding additional high pass sections connected by power dividers, and for the low frequency bands by adding a conventional OMT.

Abstract: A waveguide filter made a rectangular waveguide section 12 with cavities 14 forming resonators spaced along opposite walls of the waveguide is configured to reduce the harmonic passband amplitude noise due to higher order harmonics. The cavities 14 are modified from conventional cavities by having different lengths L1-L8 and widths A1-A8, as opposed to equal length and equal width values. Each cavity is designed to resonate at the desired principal frequency f1 according to the combination of the cavity width and length, but with cavities having different lengths and widths, synchronous resonances do not occur at higher order harmonic frequencies f2 and f3 normally occurring when the cavities all have equal widths and equal lengths.

Abstract: A windshield wiper arm of the motor vehicle is provided with a device including a first power interruption switch, a second power interruption switch, a relay, a motor, a gear set, a push red, and a protruded rod. When the push rod is driven to move in a vertical direction, the windshield wiper arm is pushed to move away from the windshield of the motor vehicle which is not in operation. As the motor vehicle is activated, the push rod is driven to return to a horizontal position thereof, thereby causing the windshield wiper arm to be retracted in place.

Abstract: A multi-channel feed network includes a main waveguide section (either square or circular) for connection to a satellite antenna for propagating two orthogonal polarizations. The feed network further includes a low pass section connected on axis with the main waveguide, the low pass section having the same cross section as the main waveguide, and a high pass section also connected perpendicular to the main waveguide. The low pass section includes a band reject filter (BRF) formed from slots cut to reject higher frequency signals. The high pass section can be a rectangular waveguide which functions to filter low frequency signals. The feed network can be configured to support a number of different polarizations. Orthogonal linear polarizations are provided for the high frequency bands by adding additional high pass sections connected by power dividers, and for the low frequency bands by adding a conventional OMT.

Abstract: An abdomen exercise device includes a bed body having a backrest and a seat pivotally connected with a joint to permit the backrest swing up and down to force the back of a user lying on the bed body bend the back up and down to exercise the user's abdomen. The backrest is swung up and down by a drive rod moved by a drive device consisting of a motor, a drive wheel, and a chain gear fixed with a lower end of the drive rod and a drive chain gear fixed eccentrically with the drive wheel rotated by the motor. With an endless chain extends around the drive chain gear and the chain gear to let two ends of the drive rod seesaw to swing up and down the backrest automatically.

Abstract: A waveguide antenna assembly includes a feedhorn having a cavity coupled to a waveguide polarizer. The waveguide polarizer includes a single aperture waveguide, septum-loaded waveguide, and a dual aperture waveguide coupled inline. The septum-loaded waveguide includes an internal septum and is formed from at least one internal wall having a varying thickness. The length of the circular feedhorn and the diameter of the feedhorn cavity can be adjusted with the length of the single aperture waveguide to maximize signal isolation between the orthogonal signal ports.

Abstract: A parabolic rectangular horn antenna includes a source aperture, a parabolic reflector, and an output aperture. The source aperture has a first port for receiving a planar wavefront signal and a second port for providing a substantially cylindrical wavefront signal. The parabolic reflector is positioned within the horn to receive the cylindrical wavefront signal, transforming it to a substantially planar wavefront signal at a predefined location. The output aperture is positioned at the predefined location and outputs the substantially planar wavefront signal. Corrugations are adjacently placed at both sides of the output aperture to optimize the antenna beam pattern.

Abstract: A wireless communication system that utilizes a circularly polarized transmitting antenna with dual orthogonal circularly polarized receiving antenna. According to some embodiments, the present invention provides a wireless communication system that includes a first transmitting antenna capable of transmitting first signals having a first type of circular polarization. The transmitting antenna is located at a first location. The system also includes a first receiving antenna capable of receiving second signals having a second type of circular polarization, where the second type of circular polarization is orthogonal to the first type of circular polarization. The system further includes a second receiving antenna capable of receiving third signals having the first type of circular polarization, and the first receiving antenna and the second receiving antenna are both located at a second location.

Abstract: Apparatus and related methods for an easily manufactured evanescent mode band reject filter that provides high performance with minimal dependence on critical dimensions. According to one embodiment, the present invention provides a band reject filter including a waveguide having an input, an output, a first wall between the input and the output, and a second wall opposite the first wall. The first wall is part of a substantially solid first block, and the second wall is part of a substantially solid second block. The waveguide is capable of transmitting an electromagnetic radiation signal from the input to the output, where the signal is at an operating frequency above a waveguide cutoff frequency. The band reject filter also includes at least one cavity coupled directly to the first wall of the waveguide, where the cavity is a substantially cylindrical cavity formed in the first block.

Abstract: An improved ultrasonic ranging device having a ultrasonic sensor unit provided for detecting the distance between a ground object and a rear end of a vehicle includes: a casing body composed of a front casing and a rear casing with a round opening formed in the opposing ends; a control unit with a plurality of microswitches and a control circuit installed at one end of the casing body and electrically connected to the ultrasonic sensor unit; a gear system with a motor and a reduction gear member disposed at another end of the casing body and electrically connected to the control circuit; and a protective cover with a transmission arrangement movably connected to the casing body with the transmission arrangement meshed with the reduction gear and the control unit; thereby, the protective cover can be automatically raised up and lowered down along with the backward and forward movements of a vehicle for protecting the ultrasonic ranging device against water, dust and mud.