Showing papers on "Return loss published in 1983"

Microwave transmission device having gyromagnetic materials having different saturation magnetizations

Abstract: A multi-port microwave device, such as an isolator or circulator, for transmission of electromagnetic energy in TEM mode non-reciprocally between ports. The device exhibits low insertion loss, high return loss (low VSWR) and high isolation and is operable over a 100 percent or more bandwidth. The microwave device includes a composite ferrite body between a circuit conductor and a ground plane. The composite ferrite body includes at least two different types of ferrite material where each one is selected to provide different frequency characteristics over the frequency pass band of the device.

A mixer for use in a microwave system

Abstract: The present invention relates to a mixer for use at high microwave frequencies (typically 21.8 x 23.2 GHz) in a low cost communications application. The invention utilizes low cost microwave components, including a low cost compartmented waveguide (27), shared by the signal and local oscillator and extensive microstrip circuitry (26). The provision of a pair of novel ¼ wave impedance transformers (31,32,33,34) coupled into the waveguide compartments provides efficient antenna and local oscillator input filtering, and efficient coupling from the waveguide sections to the microstrip circuitry. The mixer operation is carried out in the microstrip circuitry, which contains a hybrid coupler, a balanced diode detector, and the required mixer output filter. The arrangement is of low cost, and provides a low noise figure (7 db including the preamplifier), good band selectivity (15 db return loss over the communications band), and low local oscillator radiation.

A New Integrated Waveguide Transistor Mount

Abstract: A novel E-plane transistor mount for use up to the mm-wave range is presented The quasiplanar waveguide structure developed is made on thin, low dielectric substrate inserted in the E-plane of a rectangular wavequide and incorporates a microstrip, and a slotted, inhomogeneous finline partially coated with a dissipative layer Featuring excellent reproduciblity, low insertion and hiqh return loss in the waveguide band and appropriate broadband match below waveguide cutoff this design is shown to be well suited for precision measurement and amplifier applications Performance data of a realized X-band structure are reported

Public-address telephone set

Abstract: PURPOSE:To easily enter a reception state in a high-noise atmosphere and to easily enter a transmission state in a low-noise atmosphere by dividing a reception loss circuit and a transmission loss circuit respectively, and combining those loss circuits properly when a noise level exceeds a preset transmission threshold level. CONSTITUTION:When a voice is inputted to a microphone 1 in a no-noise state, the 1st and the 2nd transmission loss circuits 14 and 15 are controlled to the large amounts of loss and the 1st and the 2nd reception loss circuits 15 and 16 are controlled to the large amounts of loss, so that the circuit enters a transmission state. Then, if there is a noise exceeding the transmission threshold level and the device is in the transmission state while the amount of loss of the 1st transmission loss circuit 14 is large and the amount of loss of the 1st reception loss circuit is large, a loss amount control circuit 17 increases the amount of loss of the 2nd transmission loss circuit 13 and decreases the amount of loss of the 2nd reception loss circuit 16. At this time, the gain of areception detecting circuit 10 is increased with the control signal of a speech switch control circuit 11.

An improved conference circuit

Abstract: A conferencing scheme based on signal addition has been presented. Use of alternating inverting amplifier stages at the summing circuits considerably cancels out the effect of feedback voltages due to poor return loss of the hybrids. In the worst case, the net feedback voltage due to return loss at any subscriber line circuit is no more than twice than that encountered in one-to-one connection.

Transmission loss planning for digital networks

Abstract: This paper describes the transmission loss plan for a digital network on the basis of transmission quality evaluation data for telephone, modern and facsimile services. First, reference equivalent distribution of a subscriber loop and terminal return loss distribution at 2-wire/4-wire conversion circuit of digital local exchange subscriber circuit, which are network parameters for transmission loss planning, are estimated based on investigations of the actual conditions. Next, with respect to the telephone, the relation between transmission loss and opinion is clarified both for a short length of connection where degradation due to echo is negligible and for medium and long length of connections where the echo performance is taken into account. With respect to modem and facsimile, the relation between openloop loss and quality degradation is evaluated experimentally. As a result of total evaluation of network parameters and evaluation data with respect to telephone, modem and facsimile, it is revealed that the transmission loss in EO-EO all-digital network should be set at 4 dB for intra-office connecnection. Here, degradation due to echo is negligible and 8 dB for medium and long length of connections where echo performance is taken into account to maintain good telephone and modem-facsimile transmission quality. Finally, the transmission loss plan from existing analog network to EO-EO all digital network is shown.

Ka-band Y-circulators in integrated waveguide technology

Abstract: A simple Ka-band Y-circulator is presented, fabricated according to integrated waveguide technology (INWATE). The performance is as follows: 20 dB isolation bandwidth of 20%, and return loss and insertion loss about 20 dB and 0.5 dB, respectively. This type of circulator seems to be well suited to form part of future INWATE circuits.

Bragg Reflection Characteristics of Millimeter Waves in a Corrugated H-Guide

Abstract: The Bragg reflection characteristics of millimeter waves in a H-guide having a corrugated dielectric slab are investigated by the perturbation method of multiple scales. Brillouin diagrams in the vicinity of the Bragg frequency of the TM-TM-, TE-TE-, and TM-TE-mode couplings are shown. Validity of the theoretical predictions are confirmed by experiments carried out in the 40-50-GHz region. Typical frequency response at the stopband resulting from TM-TM-mode coupling is stop bandwidth about 380 MHz, with return loss about 2.1 dB at the Bragg frequency 47.3 GHz.

Gain varying circuit

Abstract: PURPOSE:To vary a gain by connecting a variable impedance element to the output side of an amplifier and an impedance element between its other terminal and the ground, and varying the variable impedance element. CONSTITUTION:An input signal supplied to a terminal 33 is amplified by an amplifier 34 and outputted from an output terminal 32 through a variable resistance 30. A resistance 31 is provided for adjusting output impedance; the output impedance of the amplifier is 0, the input impedance of a circuit connected to the output terminal 32 is 75OMEGA, and attenuation by resistances 30 and 31 when gain variation is 0 is 3dB. Output return loss is -20log¦(X-X0)/(X+X0)¦ (where X is the impedance of the circuit and X0 is the ideal impedance of the circuit) and shows the ratio of reflected electric power due to difference in impedance of both circuits at their connection point and ideal transmitting electric power, and the greater the value is, the better electric characteristics are. The variable resistance allows + or -2dB gain variation.

An Improved Method for RF- and Microwave-Cable Structural Return Loss Measurement for Type Testing

Abstract: A rf-cab1e structural return loss test set-up is described, which bases on a modified transmission measurement circuit. The measuring accuracy is, compared with conventional methods, much higher, because no cable connectors and no directive devices with their inherent errors are needed.

Mixer for microwave system

Abstract: The present invention relates to a mixer for use at high microwave frequencies (typically 21.8x23.2 GHz) in a low cost communications application. The invention utilizes low cost microwave components, including a low cost compartmented waveguide, shared by the signal and local oscillator and extensive microstrip circuitry. The provision of a pair of novel 1/4 wave impedance transformers coupled into the waveguide compartments provides efficient antenna and local oscillator input filtering, and efficient coupling from the waveguide sections to the microstrip circuitry. The mixer operation is carried out in the microstrip circuitry, which contains a hybrid coupler, a balanced diode detector, and the required mixer output filter. The arrangement is of low cost, and provides a low noise figure (7 db including the preamplifier), good band selectivity (15 db return loss over the communications band), and low local oscillator radiation.