Return loss

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

Thermally Actuated Latching RF MEMS Switch and Its Characteristics

Abstract: Here, a new thermally actuated latching wideband RF microelectromechanical systems (MEMS) switch is presented. The switch employs two thermal actuators connected to two thin metal arms which serve as signal lines of coplanar waveguide switch. The actuators pull the thin arms sequentially, and latch the switch. The switch can be actuated on and off by using either short voltage or current pulses. Using a dielectric bridge (nitride) as an interface between the actuators and the thin arms, the RF circuitry is separated from DC actuators, allowing wide-band operation. The switch demonstrates an excellent wideband RF performance with an insertion loss of better than 0.3 dB up to 20 GHz and better than 0.8 dB up to 40 GHz. The return loss and isolation of the switch is better than 20 dB for the entire frequency band. The switch also has a very satisfactory repeatability with better than 0.1-dB variation in insertion loss and less than 1-dB variation in return loss and isolation at 30-dB level up to 6000 times switching cycles. The switch has been also successfully tested for RF power handling capability up to 40 dBm. The proposed switch has very simple RF structure which makes it an ideal candidate to be integrated in the form of more complex circuitry. An application of the proposed switch for a band selection network which is used in multiband transceivers has been presented here.

A Fully Integrated Shark-Fin Antenna for MIMO-LTE, GPS, WLAN, and WAVE Applications

Abstract: In this study, a three-dimensional compact antenna solution for the automotive industry is proposed. The antenna solution is designed to fit in a shark-fin case and is easily fabricated from a printed circuit board and a metal sheet with low-cost process and materials. The antenna solution covers Long Term Evolution (LTE), GPS, WLAN, and Wireless Access in the Vehicular Environment (WAVE) bands (850 MHz, 1575 MHz, 2.4 GHz, and 5.9 GHz, respectively). The planar inverted-F antennas are used as multiple-input–multiple-output antennas for the LTE band due to their low-profile structure. Modified planar monopoles are used to obtain omnidirectional radiation patterns for WLAN and WAVE bands. Antenna characteristics such as return loss, isolation, and radiation pattern have been simulated and measured to confirm the possibility for use in automotive applications.

Wideband Four-Way Filtering Power Divider With Sharp Selectivity and Wide Stopband Using Looped Coupled-Line Structures

Abstract: A compact wideband four-way filtering PD is presented. The structure of the proposed device includes a pair of looped coupled-line structures to provide the needed power division to four output ports. Moreover, a pair of short-ended coupled-line stubs is used to introduce multiple transmission poles and transmission zeros for a sharp cut-off of the passband and high upper-stopband rejection. A detailed design procedure is shown to determine the initial design parameters. A prototype is designed, simulated and measured experimentally. The measured results show 56.5% bandwidth centered at 1.5 GHz with more than 15 dB upper-stopband rejection up to 4.15 GHz, more than 13 dB in-band isolation, and 15 dB return loss at all output ports.

Compact and Sharp Skirts Microstrip Dual-Mode Dual-Band Bandpass Filter Using a Single Quadruple-Mode Resonator (QMR)

Abstract: A new type of microstrip dual-mode dual-band bandpass filter (BPF) using a single quadruple-mode resonator (QMR) is proposed in this paper. The classical even-/odd-mode method is applied to analyze the characteristics of the proposed resonator, which shows that it has two pairs of symmetrical resonant modes. Owing to the inherent characteristic of a dual-mode resonator and source-load coupling, four transmission zeros can be produced and these four resonant modes can be divided in two groups, resulting in a dual-band BPF with two resonant modes in each passband. As examples, two dual-mode dual-band BPFs, Filter A with central frequencies (CFs) at 1.99/5.58 GHz and -3-dB fractional bandwidth (FBW) of 62.3%/19.7%, while Filter B with CFs at 1.64/5.26 GHz and -3-dB FBW of 32.9%/7.6%, are designed and fabricated. An aperture-backed compensation technique is employed in such two filters to enhance the coupling strength between the feeding lines and QMR. Furthermore, a meander coupled-line section is employed in the Filter A design, while a defected microstrip structure is introduced in Filter B design, so as to increase much more design freedoms for tuning filter performance. The fabricated two filters exhibit simple design procedures, low insertion losses, good return losses, sharp shirts, and compact sizes. Moreover, two BPFs do not need external input/output impedance transformation feeding lines.

Wide-slot antenna for UWB applications

Abstract: A wide-slot antenna with a fork-shaped microstrip line feed structure is investigated and optimized for UWB applications. The prototype shows good UWB behavior. The bandwidth for 10 dB return loss is more than 2 octaves (f/sub h//f/sub 1/=4.52, or (f/sub h/-f/sub 1/)/f/sub 0/=127%); it also shows a good gain flatness and phase linearity. The proposed antenna is easy to fabricate, low cost and presents stable characteristic over 3.1 GHz to 10.6 GHz, and it is suitable for future UWB applications.