摘要：Traditional multi-band frequency selective surface （FSS） approaches are hard to achieve a perfect resonance response in a wide band due to the limit of the onset grating lobe frequency determined by the array. To solve this problem, an approach of combining elements in different period to build a hybrid array is presented. The results of series of numerical simulation show that multi-periodicity combined element FSS, which are designed using this approach, usually have much weaker grating lobes than the traditional FSS. Furthermore, their frequency response can be well predicted through the properties of their member element FSS. A prediction method for estimating the degree of expected grating lobe energy loss in designing multi-band FSS using this approach is provided.

摘要：In this paper, a multi-band metasurface（MS） antenna array with low radar cross section（RCS） performance is proposed and measured. Firstly, a 44 antenna array is composed of four 22 Jerusalem cross structure antenna arrays working at different frequency bands, which is aimed at enhancing the bandwidth effectively. Then, each antenna can be seen as a unit of MS in spite of adding the feeding structure. Based on phase cancellation principle, the MS is arranged into a chessboard configuration in order to realize wideband RCS reduction. Thus, excellent radiation and scattering characteristics are obtained simultaneously. Simulated and measured results indicate that this work provides a novel method to achieve bandwidth expansion as well as wideband RCS reduction of the antenna array.

摘要：This paper presents the design and implementation of a fully integrated multi-band RF receiver frontend for GNSS applications on L-band.A single RF signal channel with a low-IF architecture is adopted for multi-band operation on the RF section,which mainly consists of a low noise amplifier（LNA）,a down-converter,polyphase filters and summing *** improved cascode source degenerated LNA with a multi-band shared off-chip matching network and band switches is implemented in the first amplifying ***,a re-designed wideband double balance mixer is implemented in the down conversion stage,which provides better gain,noise figure and linearity *** a TSMC 0.18μm 1P4M RF CMOS process,a compact 1.27 GHz/1.575 GHz dualband GNSS frontend is realized in the proposed low-IF *** measurements exhibit the gains of 45 dB and 43 dB,and noise figures are controlled at 3.35 dB and 3.9 dB of the two frequency bands,*** frontend model consumes about 11.8-13.5 mA current on a 1.8 V power *** core occupies 1.91×0.53 mm2 while the total die area with ESD is 2.45×2.36 mm^2.

摘要：A rally integrated receiver RF front-end that meets WCDMA/GSM system requirements is *** supports SAW-less operation for *** improve the linearity in terms of both IP3 and IP2,the RF front-end is comprised of multiple-gated LNAs with capacitive desensitization,current-mode passive mixers with the proposed IP2 calibration circuit and reconfigurable Tow-Thomas-like biquad TIAs.A new power-saving multi-mode divider with low phase noise is proposed to provide the 4-phase 25%-duty-cycle *** addition,a constant-g_m biasing with an on-chip resistor is adopted to make the conversion gain invulnerable to the process and temperature variations of the *** RF front-end is integrated in a receiver with an on-chip frequency synthesizer in 0.13μm *** measurement results show that owing to this high-linearity RF front-end,the receiver achieves -6 dBm IIP3 and better than ＋60 dBm IIP2 for all modes and bands.