Wideband uniplanar 180° phase switch

A wideband 180° phase switch is developed at millimetre-wave frequencies (31 GHz centre frequency) using uniplanar technology. The circuit is designed using coplanar-to-slotline transitions and commercial pin diodes as switching devices. The implementation is straightforward, fast in terms of fabrication and low-cost. The circuits tested, made on an alumina substrate, show a phase difference between states of 180° ± 2°, providing 40% bandwidth with in-band insertion loss lower than 2.5 dB and a return loss better than 10 dB. The phase switch provides a ±5° phase error in a bandwidth of around 60%, from 18 to 38 GHz.     

0.18 μm 21-27 GHz CMOS UWB LNA with 9.3 ± 1.3 dB gain and 103.9 ± 8.1 ps group delay

A 21-27 GHz CMOS ultra-wideband low-noise amplifier (UWB LNA) with state-of-the-art phase linearity property (group delay variation is only ± 8.1 ps across the whole band) is reported for the first time. To achieve high and flat gain (S₂₁) and small group delay variation at the same time, the inductive series peaking technique was adopted in the output of each stage for bandwidth enhancement. The LNA dissipated 27 mW power and achieved input return loss (S₁₁) of 213 to 220.1 dB, output return loss (S₂₂) of 28.2 to 230.2 dB, flat S21 of 9.3 ± 1.3 dB, reverse isolation (S₁₂) of 252.7 to 273.3 dB, and noise figure of 4.9?6.1 dB over the 21-27 GHz band of interest. The measured 1 dB compression point (P_1dB) and input third-order intermodulation point (IIP3) were 214 and 24 dBm, respectively, at 24 GHz.     

Wide bandwidth and broad beamwidth microstrip patch antenna

A novel wideband and broad-beam microstrip antenna loaded with gaps and stubs is proposed. The antenna is based on a two-layer stacked electromagnetic coupling microstrip patch antenna (ECMSA). The upper patch of the antenna is loaded with two arc gaps and three stubs. The ECMSA is used to achieve wide impedance bandwidth, while the gaps and stubs-loaded patch is used to obtain broad-beam. The impedance bandwidth is up to 34.6%. In this impedance bandwidth, the pattern bandwidth is 13%. In this pattern bandwidth, the 3 dB beamwidth of E-plane and H-plane remain stable and are about ±60°. Simulation results agree well with measured results.     

Miniaturised artificial magnetic conductor design using lumped reactive components

A miniaturised artificial magnetic conductor (AMC) using lumped capacitors is introduced. Simulated reflection phase data is presented, which proposes a unit cell periodicity of α/49, with ±90° bandwidth of 10%. Simulated and measured return loss and radiation patterns are presented, which show that the miniaturised AMC provides < - 10 dB return loss at resonance and 10 dB of back radiation reduction.     

Passive broadband millimetre-wave uniplanar MMIC balun

A new uniplanar monolithic microwave integrated circuit (MMIC) balun using lumped circuits is presented. The proposed planar balun consists of a wideband Wilkinson power divider and a broadband 180° phase shifter using novel series and parallel LC reflective terminating circuits. To demonstrate the design methodology, a 24?44 GHz MMIC balun was realised as a 1.4 mm _{GaAs chip. The measured return losses for the unbalanced and balanced ports are better than 212, 210 and 27 dB, respectively. The measured amplitude and phase imbalance between the two output ports are less than 0.5 dB and 7°, respectively, and maximum insertion loss is 5 dB.}     

Dual Band Planar Spiral Feed Backed by a Stepped Ground Plane Cavity for Satellite Boresight Reference Antenna Applications

This paper presents development of a new planar spiral feed for a satellite boresight reference antenna, operating at two widely separated frequency bands (2200–2300 MHz and 8000–8400 MHz). A stepped ground plane cavity with different quarter wavelength distances is proposed to provide unidirectional patterns at these frequency bands. A back lobe suppression of around 12 dB in 2 GHz band and better than 15 dB in 8 GHz band with a measured on-axis axial ratio of less than 3 dB is achieved for the dual band planar spiral feed with stepped ground plane cavity configuration. A boresight reflector antenna employing this feed has measured beamwidths of 7 degrees and 1.8 degrees respectively and gain of 26 dBi and 36 dBi at 2250 MHz and 8200 MHz.      

Dual polarised microstrip patch antenna with high port isolation

A probe fed stacked microstrip patch antenna for operation in dual polarisation mode is proposed. A slot loaded lower patch is presented to improve isolation between the two polarisation ports. Simulations and measurements show two linear polarisations with an isolation of more than 30 dB within the band 2.5-2.7 GHz. A return loss of -10 dB is achieved within the above-mentioned bandwidth for the proposed antenna. The radiation pattern for the antenna is similar to that of a conventional microstrip antenna and the measured cross-polar level is 16.5 dB below the peak co-polar level within the band 2.5-2.7 GHz     

Broadband CPS-fed Yagi-Uda antenna

A broadband coplanar stripline-fed Yagi-Uda antenna is presented. The antenna has a feedline structure that is much simpler than other Yagi- Uda antennas, and provides more design flexibility in arranging the reflector owing to the absence of a large ground plane. To improve the impedance match, a taper is inserted between the wide-line/ small-gap and the narrow-line/large-gap CPS. The proposed antenna has a bandwidth of 3.9?5.9 GHz for a 210 dB reflection coefficient and a gain of 6.5?8.0 dBi. At the centre frequency of 4.9 GHz, the antenna has gain of 7.1 dBi, and a half-power beamwidth (HPBW) of 73° in the E-plane and 98° in the H-plane.     

Sigma?delta digital drive signals for switchmode power amplifiers

A novel all-digital approach to generate a pulse train to drive switchmode power amplifiers is proposed. Sigma?delta (ΣΔ) techniques are used to shape time quantisation noise away from the band of interest. The proposed architecture promises greater than 10 dB improvement in adjacent channel power over an existing scheme. The key contribution is to quantise in the polar domain while performing the ΣΔ filtering in the Cartesian domain.     

UWB Gilbert downconverter utilising a wideband LR-CR quadrature generator

An ultra-wideband (UWB) I/Q downconverter with an LR-CR quadrature generator is demonstrated using 0.35 μm SiGe HBT technology. The I/Q outputs of this generator are always in quadrature phase at any frequency while the BJT-type active mixer inherently tolerates much LO power difference for a flat gain response. Consequently, the amplitude imbalance and phase error of the I/Q outputs are less than 1 dB and 2° in the RF frequency range 3?11 GHz.     

一种双金属板加载的水平极化全向天线

设计了一种双金属板加载水平极化全向天线,包括顶端反射板、微带天线、支撑介质柱和底端反射板等4个部分。微带天线由4个弧形微带偶极子沿圆周排列组成;介质柱的法兰固定天线;顶端和底端金属板对称地放置于微带天线上下两侧,调整顶端和底端金属板的尺寸可以改变波瓣仰角。仿真结果表明,天线在10%的相对频带内端口驻波小于1.5;方位面内增益高于2.3 dB,增益起伏小于1 dB,交叉极化电平低于-30 dB。测试结果表明,在频带内端口驻波小于1.7;方位面波瓣起伏约2.1 dB。     

A 48–860 MHz CMOS Low-IF Direct-Conversion DTV Tuner

A CMOS low-IF direct-conversion digital TV (DTV) tuner needs no off-chip harmonic rejection and image filters to receive both terrestrial and cable TV channels in the 48 to 860 MHz frequency range. Complex in-phase and quadrature (I/Q) poly-phase mixing together with coarse active RF filtering suppresses the third-harmonic mixing by 72 dB, and a digital LMS image correlation algorithm reduces the image leakage by 61 dB. A global AGC scheme keeps the signal level in the down-conversion mixer constant, and warrants the RF front-end linearity with strong blockers. Anti-aliasing and digital channel filters are made digitally programmable so that DTV standards with 6–8 MHz channel bandwidths can be supported. The measured system noise figure is 4–7 dB over the whole TV band. When measured at 500 MHz, the sensitivity is $-$86 dBm with ATSC-T 8-VSB signal, and the MER is 31.5 dB with actual J.83/B 256-QAM signal from a commercial CATV source. The chip implemented in 0.18 $mu{hbox{m}}$ CMOS occupies 5$times {hbox{5 mm}}^{2}$, and consumes 750 mW at 1.8 V.      

宽带低交叉极化超材料漏波天线的设计

基于基片集成波导结构提出了一种新型双层电磁超材料单元，并验证了其左手特性。将超材料单元应用于漏波天线的设计，所设计的天线由15个双层电磁超材料单元组成。将设计好的天线进行加工测试，测试与仿真结果吻合较好，表明漏波天线的工作频带为7.20~12.70GHz，在工作频带内可实现从后向-78°到前向+80°的连续主波束扫描，天线在工作频带内的测试增益均大于10dBi，峰值增益为15.2dBi，3dB增益带宽达到50.2%。此外，该漏波天线具有很低的交叉极化电平，交叉极化始终比主极化低至少30dB。相比于新近文献报道的同类型超材料漏波天线，所设计的天线具有更加优越的电气性能。     

K波段低副瓣波导缝隙驻波阵设计

本文设计了一种 K 频段低副瓣波导缝隙驻波阵天线,给出了实现低副瓣的方法。设计副瓣电平为-27dB,缝隙幅度分布按-30dB 泰勒分布计算,结合高频仿真软件 Ansoft HFSS 对各缝隙归一化导纳进行计算,建立仿真模型并优化天线各参数。依据设计结果加工实物并测试其方向图及增益。测试结果表明,该天线在工作频带内波束宽度约 3°,副瓣电平小于-27dB,工作频带内增益大于 30.8dB,仿真结果与实测结果相符,设计满足指标要求。     

SOA-pumped erbium-doped ASE fibre source with flattened spectrum and high power density

A spectrum-flattened two-stage amplified spontaneous emission (ASE) fibre source is proposed and experimentally demonstrated. The source is structured by an erbium-doped fibre simultaneously pumped by a 980 nm laser and a semiconductor optical amplifier (SOA) source. In the wavelength range of 1526?1563 nm, a spectrum ripple of ±0.5 dB and an average power density of 214 dBm/0.1 nm are achieved.     

High TX-to-RX Isolation in UHF RFID Using Narrowband Leaking Carrier Canceller

Ultra-high frequency (UHF) radio frequency identification (RFID) system suffers from large leakage of the carrier due to insufficient TX-to-RX isolation. A narrowband leaking carrier canceller (LCC) for UHF RFID is proposed to enhance the isolation. Hardware realization is carried out based on simulation model in ADS (Advanced Design System). Measurement results indicate that the TX-to-RX isolation is improved from 20 dB to above 40 dB within UHF RFID frequency band of 920–925 MHz. Upper limit of increase in isolation versus amplitude and phase distortion are also presented and discussed.      

A 60–110 GHz Transmission-Line Integrated SPDT Switch in 90 nm CMOS Technology

This letter demonstrates a fully integrated transmit/receive single-pole-double-throw switch in standard bulk 90 nm CMOS process. This switch is based on the transmission-line integrated approach that reduces the effect of parasitic capacitance of transistors in the desired band, and this approach can achieve good isolation and return loss with fewer stages of transistors and broad bandwidth. The switch provides an insertion loss of 3–4 dB and a return loss better than 10 dB in 60–110 GHz. The measured isolation is better than 25 dB. The measured 1 dB compression point of input power is 10.5 dBm at 75 GHz. To the best of our knowledge, this is the first CMOS switch operating beyond 100 GHz.      

Ultra-low temperature sensitive deep-well quantum cascade lasers (λ - 4.8 μm) via uptapering conduction band edge of injector region

A new design feature for deep-well quantum cascade (QC) lasers, in which the conduction band edge of the injector region is uptapered, results in virtual suppression of carrier leakage out of the active regions of 4.8 mm emitting devices. For heatsink temperatures in the 20?90°C range the characteristic temperature coefficients for threshold, T₀, and slope efficiency, T₁, reach values as high as 278 and 285 K, respectively, which are nearly twice the values for conventional QC lasers. At 20°C, the threshold current density for uncoated, 30 period, 3 mm-long devices is only ~1.8 kA/cm².     

A low phase shift attenuator

A PIN diode attenuator with an average of 0.25°/dB phaseshift between 2.5 GHz and 5.3 GHz has been modelled and constructed. In particular the attenuator has similar phase at 0 dB and 12 dB of attenuation to within 0.5° over most of the band. The input match is better than 10 dB over the attenuation range of 0 to 10 dB     

End-to-end delay in wireless random networks

The focus of this letter is to derive a scaling law for the ene-to-end delay of wireless random networks under node mobility, where n nodes randomly move with the speed of v. To that end, we apply the cover time analysis and relate it to the delay scaling law. As a result, we derive that the mean delay per S-D pair as θ(n) or θ(√n÷v), and the worst case delay is θ(n log n) or θ(√log n÷v), corresponding to one slot time length that is either constant or 1÷v√n .