http://ieeexplore.ieee.org TOC Alert for Publication# 7260 2013 May 21 23 5 C1 C4 135 23 5 C2 C2 154 . In effect, this enables local space refinement without necessitating a smaller time step. In particular, this is very useful for thin layers of highly conducting material or to treat complex media, such as plasma, allowing evanescent waves.]]> 23 5 225 227 575 23 5 228 230 968 23 5 231 233 625 23 5 234 236 462 ${- 20}~{rm dB}$ reflection over 90–100 GHz (except in two small regions), which is in good agreement with the numerical simulation presented in this letter.]]> 23 5 237 239 639 $({rm K} > 1)$ and the source-load coupling lines. By tuning the impedance ratio and length ratio $(alpha)$ of SIRs, the resonant modes can be easily determined so as to implement a two-order bandpass filter with very close dual-passbands. The source-load coupling lines are designed to correspond to the quarter-wavelength at the center frequency of first passband for each output port. The proposed quad-channel diplexer is showing a simple configuration, an effective design method and a small circuit size.]]> 23 5 240 242 843 ${rm TM}_{110}$-similar mode. Three asymmetric bandpass filters utilizing this resonator are designed and fabricated. The measured results are in good agreement with the simulation results.]]> 23 5 243 245 791 ${sim} 50hbox{%}$ increase in the cross-polarization peak frequency, changing it from 6 to 9 GHz, for a linear polarization incidence perpendicular to the helices. Tuning rotates the transmitted wave polarization ellipse by ${sim} 15^{circ}$.]]> 23 5 246 248 636 23 5 249 251 578 23 5 252 254 628 $Omega$ constant impedance BS and a heart-shaped slotline cavity. Unlike traditional slotline transitions, the proposed transition does not suffer from matching issues when losses are incurred by multi-section impedance transformers and this transition has a potential to operate from 530 MHz to over 20 GHz if a K-connector is used. This letter will illustrate the discovery of BS with constant impedance first and then its application in design of the 50-$Omega$ BS. The heart-shaped slotline cavity is proposed for bandwidth improvement. And the transition size is also reduced due to the absence of multi-section impedance transformers. A prototype is fabricated and measured to demonstrate this concept of the design, and it has a practical operating bandwidth from 0.53 to 12.23 GHz (about 23:1) with return loss better than 10 dB and insertion loss less than 3 dB.]]> 23 5 255 257 738 $lambda/4$ resonators. The first and third passbands are realized by coupling the two dual-band $lambda/4$ stepped impedance resonators (SIRs) with synthesized frequency response. Meanwhile, the second passband in the middle is achieved by introducing the two coupled $lambda/4$ uniform impedance resonators (UIRs). A non-uniform coupled-line with the U-folded shape on one line is then proposed to independently achieve the dissimilar external couplings as desired in the tri-passbands. In parallel, the quadruplet topology for each band is formulated by introducing an additional weak I/O cross coupling, thereby bringing one pair of transmission zeros at each side of all the triple passbands, In final, a tri-band BPF with the central frequencies of 1.8, 3.5, and 5.8 GHz, and respective fractional bandwidths of 7.0%, 5.0%, and 3.5% is designed and fabricated. The measured results show good consistence with the simulated ones.]]> 23 5 258 260 629 $mu{rm m}$ SiGe BiCMOS is proposed. A Q-enhanced cascode approach with a filter synthesis passband-forming technique was employed to achieve gain and selectivity improvement simultaneously. The amplifier achieved a gain of above 45 dB and a noise figure of 6–8.3 dB at 77–101 GHz with a power consumption of 19.2 mW. The LNA has high selectivity with a 3 dB-to-35 dB shape factor of 2.1, which is comparable with silicon-based passive millimeter-wave filters.]]> 23 5 261 263 856 $mu{rm m}$ CMOS process with a chip size of 1.04 ${rm mm}^{2}$, wherein the suspended MEMS structure is released through the post-CMOS micromachining. Three discrete phase states, including 0$^{circ}$, 89$^{circ}$, 144$^{circ}$ at 65 GHz, can be achieved by the bi-directional fishbone actuators under 46-V actuation voltage. The measured insertion loss is $2.2pm 1~{rm dB}$ and the return loss is better than 14 dB over the 55–65 GHz frequency range, demonstrating a great potential in many applications.]]> 23 5 264 266 940 $S$ -band power amplifier. The pHEMT modulator architecture and design tradeoffs affecting circuit size, speed, and reliability are discussed. Electrical performance is validated in the fast time domain, with detected rise and fall times of 6 and 4 ns, respectively, and achievable RF pulse widths as narrow as 25 ns. A novel all-phase mismatch test is used to evaluate modulator peak current handling over a matrix of operating conditions varying duty cycle from 5 to 45% and temperature from ${-}$ 55 to ${+}$ 85$^{circ}$ C; peak currents of up to 9 A are induced at a supply voltage of 28 V, with no observed degradation in electrical performance. Thermal measurements taken using high-resolution Raman scattering thermometry in conjunction with infrared imaging confirm that maximum channel temperatures in the modulator subcircuit are within safe operating limits.]]> 23 5 267 269 550 23 5 270 272 409 23 5 C3 C3 277