Showing papers on "Return loss published in 1986"

Multioctave bandwidth log-periodic microstrip antenna array

Abstract: The application of the log-periodic technique to the series-fed electromagnetically coupled overlaidpatch array allows antennas with flat conformal characteristics and wide bandwidths to be obtained. A k-s analysis of this and other microstrip array types indicate that the microstrip patch is not an optimum element for log-periodic arrays and that direct connection will result in arrays having a limited bandwidth. The addition of series capacitance to the patch equivalent circuit, implemented by electromagnetic coupling, allows an optimum to be approached. Log-periodic overlaid patch array design and measured results for an array with a 4:1 bandwidth are presented. These, together with a transmission-line analysis, indicate the array-design trade offs available and that the ultimate bandwidth is limited primarily by changes in the input return loss and radiation pattern due to the use of uniform thickness substrates.

Low insertion-and high return-loss optical connectors with spherically convex-polished end

Abstract: PC connectors with spherically convex-polished ends, whose fibre ends make close contact, have recently been developed. This connector features extremely low insertion-and high return-loss characteristics, and is also easily produced with good environmental performance. For a single-mode PC connector, the average insertion loss is measured to be as small as 0.17 dB with a return loss of 28 dB. Detailed evaluation of this connector is now under way for use in a trial optical transmission system.

A High Performance 2-18.5 GHz Distributed Amplifier, Theory and Experiment

Abstract: A high-performance 2-18.5-GHz monolithic GaAs MESFET distributed amplifier has been designed and fabricated. The distributed amplifier is analyzed theoretically using a normalized transmission matrix approach, and a closed-form gain equation is presented for the MMIC m-derived drain-line case. Theoretical predictions are compared to measured results and more complicated CAD models. The measured small, signal gain is typically 8.0±0.40 dB from 2-18.5 GHz at standard bias. Typical input return loss is greater than 12 dB, and the output return loss is greater than 15 dB. The saturated output power is in excess of 23 dBm over most of the band, and the noise figure is less than 7.5 dB.

A 2 to 8 GHz Leveling Loop Using a GaAs MMIC Active Splitter and Attenuator

Abstract: A wide-band monolithic GaAs bridged-T variable attenuator has been used with a monolithic GaAs active power splitter to form a compact, 2 to 8 GHz leveling loop for RF sources having a minimum 12dB leveling range with buffered output. The attenuator internally optimizes input and output return loss over a 1 to 10 GHz bandwidth by the use of an on-chip GaAs op-amp. The active power splitter provides unity gain to each port over a 1 to 10 GHz bandwidth by the use of distributed amplification. The entire 4.5 cm by 42 cm subsystem was realized with surface mount packages on RT-Duroid®®.

Surface-Mounted GaAs Active Splitter and Attenuator MMIC's Used in a 1-10-GHz Leveling Loop

Abstract: A wide-band monolithic GaAs bridge-T variable attenuator has been used with a monolithic GaAs active power splitter to form a compact 1-10-GHz leveling loop having a minimum 9-dB leveling range with buffered output. The attenuator internally optimizes input and output return loss over a 1- 10-GHz bandwidth by the use of an on-chip GaAs op-amp. The active power splitter provides unity gain to each port over a 1-10-GHz bandwidth by the use of distributed amplification. The entire 4.5-cm by 4.2-cm subsystem was realized with surface mount packages on RT-Duroid®, demonstrating new construction techniques for GaAs MMIC assembly.

High return loss connector design without using fibre contact or index matching

Abstract: A noncontacting connector design which reduces the returned power from reflections is demonstrated. The design takes advantage of the poor coupling characteristics between tilted Gaussian beam modes of single-mode fibre. The connector's mean return loss is -38 dB and its mean insertion loss is 0.7 dB.

A W-Band Monolithic GaAs PIN Diode Switch

Abstract: A state-of-the-art performance has been achieved for a W-band monolithic single-pole-single-throw PIN diode switch. An insertion loss of less than 0.5 dB with return loss greater than 15 dB (transmission mode) and an isolation greater than 11 dB (isolation mode) have been measured over a 6 GHz bandwidth (80 to 86 GHz).

Mutual Interference Between the Guided Wave and the Leaky Wave Regions and its Effects on the Performance of Dielectric Grating Filters

Abstract: In an open periodic structure with finite length, a new interaction between the guided-wave and the leaky-wave regions in the omega - beta diagram does occur. The effect of such an interaction on the characteristics is investigated rigorously by using our network approach already proposed. Numerical calculations show that the finite length of periodic structures significantly affects the stopband characteristics of the first Bragg reflection region, especially in producing a complicated behavior of the return loss due to radiation. This paper also shows that such a return loss behavior can be easily estimated from the radiation characteristics of only the first step discontinuity of the periodic structure.

Microwave branching filter

Abstract: PURPOSE: To exactly separate a microwave signal by constituting a microwave branching filter of a coaxial filter formed by connecting in series a comb-line filter and plural coaxial resonators through a capacitor. CONSTITUTION: A comb-line filter is formed by electrodes 6, 8 and 9, 7 which have been provided on a dielectric 10, and used as a first BPF of a transmission frequency band of a low frequency band. Also, by electrodes 21∼35 which have been provided on dielectric block 16∼20, internal conductors 11∼15 are connected in series through a capacitor, and a coaxial filter is formed, and used as a second BPF of a reception frequency band of a high frequency band. This microwave branching filter is constituted of the comb-line filter whose high frequency skirt characteristic is steep and the coaxial filter whose low frequency skirt characteristic is steep, therefore, a microwave signal of a part where two frequency bands are adjacent to each other is separated exactly, no leakage generated mutually, and the return loss is also improved. COPYRIGHT: (C)1988,JPO&Japio

Compact bulk optical isolator with monomode fibre pigtails for use at 1.3 μm

Abstract: A compact optical isolator has been designed, with monomode optical fibre pigtails, for use at a wavelength of 1.3 μm. The device has an isolation of greater than 26 dB and a fibre-to-fibre insertion loss of 3.5 dB, and the return loss is better than 26 dB.

A compact horn antenna with low return loss

Abstract: A horn antenna that is designed as a match between a rectangular metal waveguide and free space is described. The antenna has a very low return loss and low sidelobes. The design is based on the taper described by Hecken.

Practical realization of a K-Band test-jig for MIC components

Abstract: A test-jig for microwave integrated circuit (MIC) components in the K-band is presented. A prototype with centre frequency at 19 GHz has been built and tested. Results over 1 GHz bandwidth show a return loss better than 20 dB, an insertion loss better than 1 dB, and the waveguide-to-waveguide isolation is 35 dB in the 18–20GHz band.

Polarization-Preserving Fiber-Optic 2X2 Directional Coupler

Abstract: A low loss, wideband, compact, polarization-preserving fiber-optic directional coupler (PPFDC) has been developed for use in future coherent optical fiber transmission systems or gyroscopes. The PPFDC is made of two 200-pm-diameter sapphire ball lenses, a 3dB beam splitter, and four conical alumina-ceramic ferrules with flat reference planes to preserve polarization at the connection of the fibers. Built-in thermal stress change in the fiber is minimized because the fiber is polished only for the short length within the straight ferrule. The optical and mechanical axes are tilted, so cross-talk light from the fiber endfaces or lens surfaces is avoided. The optical directivity of the PPFDC is more than 50 dB, and return loss is more than 40 dB in the 1.3 kim wavelength region. The excess loss is less than 1 dB in the 1.2 to 1.4 Am wavelength range. The extinction ratio is more than 25 dB. The length of the coupling region of the PPFDC is about 1 mm including the two ball lenses and beam splitter. Spectral linewidths of a fiber-interfaced distributed-feedback (DFB) laser diode are measured by a delayed self-homodyne detection scheme, using the PPFDC. Experimental results of a novel polarization-preserving fiber-optic gyroscope using a phase-modulating PPFDC showed reasonable sensitivity and stability. These experimental results verified the above-mentioned characteristics of the PPFDC.

Present Status of Mechanical Connectors for Optical Fiber

Abstract: Trunk transmission network systems connecting exchange offices were the first transmission systems using optical fiber cables. Subscriber network systems connecting the exchange office with each subscriber including local area networks or CATV network systems are under development at present. Two main techniques are newly required to be developed for making optical fiber mechanical connectors for optical fiber subscriber network system realization. The first is to realize a new connector with a high return loss and a low connecting loss. The second is to cut the joining cost of optical fibers. The newly developed "optical contact connector" realized a high return loss of more than 25 dB and a low connecting loss of 0.15 dB average value. A newly developed "multifiber connector" which can connect many optical fibers at the same time can save time and space for joining fiber cables, and also a "plastic molding technique" can save the cost of the connector. The performance of all these connectors is the same as that of the "optical contact connector." This paper describes the present status of the technique to obtain a high return loss connector, a multifiber connector, and a plastic molded connector for the subscriber network system.

Experimental and numerical investigation of stacked circular microstrip antennas

Abstract: The impedance bandwidth and radiation patterns of the stacked circular microstrip antennas are investigated. Both dominant TM11 and the higher TM21 modes of operation are considered and the effect of feed point location, the separation of the patches on the return loss and the radiation patterns are studied. Sample results are presented graphically.