Return loss

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

Compact Millimeter-Wave Bandpass Filters Using Quasi-Lumped Elements in 0.13- $\mu$ m (Bi)-CMOS Technology for 5G Wireless Systems

Abstract: A design methodology for a compact millimeter-wave on-chip bandpass filter (BPF) is presented in this paper. Unlike the previously published works in the literature, the presented method is based on quasi-lumped elements, which consists of a resonator with enhanced self-coupling and metal–insulator–metal capacitors. Thus, this approach provides inherently compact designs comparing with the conventional distributed elements-based ones. To fully understand the insight of the approach, simplified LC-equivalent circuit models are developed. To further demonstrate the feasibility of using this approach in practice, the resonator and two compact BPFs are designed using the presented models. All three designs are fabricated in a standard 0.13- $\mu \text{m}$ (Bi)-CMOS technology. The measured results show that the resonator can generate a notch at 47 GHz with the attenuation better than 28 dB due to the enhanced self-coupling. The chip size, excluding the pads, is only $0.096 \times 0.294$ mm2. In addition, using the resonator for BPF designs, the first BPF has one transmission zero at 58 GHz with a peak attenuation of 23 dB. The center frequency of this filter is 27 GHz with an insertion loss of 2.5 dB, while the return loss is better than 10 dB from 26 to 31 GHz. The second BPF has two transmission zeros, and a minimum insertion loss of 3.5 dB is found at 29 GHz, while the return loss is better than 10 dB from 26 GHz to 34 GHz. Also, more than 20-dB stopband attenuation is achieved from dc to 20.5 GHz and from 48 to 67 GHz. The chip sizes of these two BPFs, excluding the pads, are only $0.076\times 0.296$ mm2 and $0.096\times 0.296$ mm2, respectively.

Hybrid narrow-band tunable bandpass filter based on varactor loaded electromagnetic-bandgap coplanar waveguides

Abstract: A varactor-loaded resonator inserted between two Bragg reflectors has been implemented to design high-selectivity tunable bandpass filters. First, a mechanical tuning method is demonstrated. A varactor tunable bandpass filter is then implemented at 9 GHz, yielding good agreement between computational and experimental results. The tuning range reaches 3.5% with a loaded quality factor Q/sub L/=40, a maximum insertion loss of 4.75 dB, and a return loss exceeding 20 dB. The theory is carefully explained, showing the importance of the parameters of the Bragg reflectors and of the resonator, in particular, the effect of diode-case parasitics and varactor position with respect to the resonator. A large-signal experimental analysis is done, showing a maximum allowable input power of a few dBm. Finally, possible filter improvements are discussed, and simulations with a microelectromechanical systems varactor are shown.

Design and development of a CPW-based 5-bit switched-line phase shifter using inline metal contact MEMS series switches for 17.25 GHz transmit/receive module application

Abstract: A radio frequency micro-electro-mechanical system (RF-MEMS) phase shifter based on switchable delay line concept with maximum desirable phase shift and good reliability is presented in this paper. The phase shifter is based on the switchable reference and delay line configurations with inline metal contact series switches that employs MEMS systems based on electrostatic actuation and implemented using coplanar waveguide (CPW) configuration. Electromechanical behaviour of the MEMS switch has been extensively investigated using commercially available simulation tools and validated using system level simulation. A detailed design and performance analysis of the phase shifter has been carried out as a function of various structural parameters with reference to the gold-based surface micromachining process on alumina substrate. The mechanical, electrical, transient, intermodulation distortion (IMD) and loss performance of an MEMS switch have been experimentally investigated. The individual primary phase-bits (11.25°/22.5°/45°/90°/180°) that are fundamental building blocks of a complete 5-bit phase shifter have been designed, fabricated and experimentally characterized. Furthermore, two different 5-bit switched-line phase shifters, that lead to 25% size reduction and result in marked improvement in the reliability of the complete 5-bit phase shifter with 30 V actuation voltage, have been developed. The performance comparison between two different CPW-based switched-line phase shifters have been extensively investigated and validated. The complete 5-bit phase shifter demonstrates an average insertion loss of 5.4 dB with a return loss of better than 14 dB at 17.25 GHz. The maximum phase error of 1.3° has been obtained at 17.25 GHz from these 5-bit phase shifters.

Triple band-notched UWB antenna using meandered ground stubs

Abstract: In this paper, three pairs of meandered ground stubs are used to create a triple band-notched characteristic for a compact planar-monopole antenna used in the ultrawide band (UWB). The three band notches include the IEEE 802.16 (WiMax) band (3.3–3.6 GHz), the lower wireless area network (WLAN) band (5.15–5.35 GHz) and the higher WLAN band (5.725–5.825 GHz). The center frequencies and bandwidths of the notches can be adjusted using the dimensions of the meandered ground stubs. Prototype of the proposed antenna is designed and fabricated. The band-notched characteristics, return loss, radiation patterns, peak gains and efficiencies of the antenna are studied using both computer simulation and measurements.

An integrated active microstrip reflectarray element with an internal amplifier

Abstract: A new active microstrip reflectarray element (unit cell) with an internal microwave integrated circuit amplifier is introduced. The amplifier resides in a small slot within the footprint of the square patch antenna and is connected between the feed points for the patch's orthogonal polarizations. This element results in reduced array element spacing, reduced transmission line losses through elimination of long feed lines, and a simplified fabrication process compared to other active reflectarray unit cells. Patch geometries with several slot shapes are studied with simulations to arrive at an antenna configuration with good return loss and isolation characteristics. The stability and gain of the system are analyzed over frequency. Measured radiation pattern and gain data for a single element and a small array agree well with predictions and demonstrate the element's capabilities. Limitations of the active element, approaches to mitigate these limitations, and directions for future work are discussed.