Return loss

About: Return loss is a research topic. Over the lifetime, 11090 publications have been published within this topic receiving 97603 citations.

A low-loss, single-pole, four-throw RF MEMS switch driven by a double stop comb drive

Abstract: Our goal was to develop a single-pole four-throw (SP4T) radio frequency microelectromechanical system (RF MEMS) switch for band selection in a multi-band, multi-mode, front-end module of a wireless transceiver system. The SP4T RF MEMS switch was based on an arrangement of four single-pole single-throw (SPST) RF MEMS switches. The SP4T RF MEMS switch was driven by a double stop (DS) comb drive, with a lateral resistive contact, and composed of single crystalline silicon (SCS) on glass. A large contact force at a low-drive voltage was achieved by electrostatic actuation of the DS comb drive. Good RF characteristics were achieved by the large contact force and the lateral resistive Au-to-Au contact. Mechanical reliability was achieved by using SCS which has no residual stress as a structure material. The developed SP4T RF MEMS switch has a drive voltage of 15 V, an insertion loss below 0.31 dB at 6 GHz after more than one million cycles under a 10 mW signal, a return loss above 20 dB and an isolation value above 36 dB.

Compact double-mode cross-coupled microstrip bandpass filter with tunable transmission zeros

Abstract: A compact double-mode cross-coupled microstrip bandpass filter with an asymmetric frequency characteristic and three transmission zeros is presented. The bandpass filter consists of a cross-coupled gap and a double-mode resonator of a half-wavelength line with a shunt-stepped-impedance open stub. In comparison to the conventional square loop dual-mode resonator, the proposed double-mode resonator achieves a 59% size reduction. The parametric studies on the electrical length of the open stub and the capacitance of the cross-coupling are provided in order to gain a better insight into the transmission poles and zeros. Then, a bandpass filter is designed, fabricated and tested to validate the design concept. From 2.3 to 2.5 GHz, the return loss is better than 10 dB and the insertion loss is <1.5 dB. There are three transmission zeros in the upper stopband at 2.8, 3.4 and 4.9 GHz.

Traveling-wave microwave power divider composed of reflectionless dividing units

Abstract: We propose a new waveguide type traveling-wave microwave power divider that is adequate for high power applications. The divider is composed of multiple stages of reflectionless dividing units, each having two output ports. Design formulas for reflectionless equal-power dividing are first derived. Structural parameters for wideband design of two- to six-stage dividers are then obtained by means of numerical analyses based on an equivalent circuit. Comparison of experiments at X-band shows good qualitative agreement with the analyses. Typical measured bandwidth for relative divided powers deviation of less than /spl plusmn/0.5 dB was 2.7 GHz, and that for -20 dB return loss was more than 3.2 GHz for the four-stage (eight-way) divider. The divider presented here has excellent features; the bandwidth for equal-power dividing decreases very little and the bandwidth for low return loss increases with increasing number of the dividing stages. It also has advantages of low insertion loss and flexibility over the number of the dividing stages. >

Electromagnetic Waves Under Sea: Bow-Tie Antennas Design for Wi-Fi Underwater Communications

Abstract: In this paper the propagation of electromagnetic waves in a medium with non zero conductivity is discussed, analyzing the dielectric properties of the sea water, in order to accurately characterize a wireless communication channel. Mathematical models for sea water dielectric constant, wavelength, propagation speed and path loss when an electromagnetic wave at 2.4 GHz propagates through sea water are presented. A Bow-Tie microstrip antenna that is required to overcome the high path loss and bandwidth requirements in sea water is studied. A dual-band antenna, with arc- shaped circular slots, operating for IEEE802.11 b/g/n standards, at 2.4 GHz and 5.1 GHz for WLAN communications, with dimensions 1.4 cm 2 is implemented. Return loss, input impedance and gain have been extracted in order to characterize antennas' performance in a conductive medium.

Error-controlled high power linear amplifiers at VHF

Abstract: Two amplifiers, each covering a different band in the VHF range, were constructed for test set applications. These amplifiers were required to meet stringent specifications beyond the general scope of previous art. These specifications related to the simultaneous availability of relatively large output power, tight linearity, minimal delay distortion across a 40 per cent band, high input and output return loss, large dynamic range, and time stability. The performance problems were solved by using: (i) Quadrature couplers in a corporate structure array to provide a high multiplicity of “paralleled” transistors, yielding both the power and return loss capabilities. (ii) The emitter follower configuration as the basic amplifier element, providing broad band, high level performance owing to the large self degeneration of that configuration. (iii) A “feed-forward,” instead of a feedback, system for error control and noise cancellation.