Showing papers on "Ka band published in 2003"

Development of substrate integrated waveguide power dividers

Abstract: Two classes of substrate integrated waveguide (SIW) power divider are presented, namely, Y- and T-types. Using arrays of via, the SIW power dividers and microstrip transitions are integrated on the same substrate. Design models are presented respectively for the Y- and T-junctions. Experimental results over the Ka band are given for both structures. The Y-junction shows a bandwidth of 25.2% at -18.5 dB while the T-junction shows a bandwidth of 10.2% at -19.0 dB.

Ka-band reflectarray using ring elements

Abstract: A simple ring structure to realise a Ka-band circularly polarised microstrip reflectarray is presented. With rotation techniques employed to focus the reflected wave at a focal point, a 0.5 m right-hand circularly polarised microstrip reflectarray is developed and tested at 31.75 GHz resulting in 50% aperture efficiency. The cross-polarisation levels measured are 40.7 dB down at broadside, showing the validity of the structure.

Modeling and design for electrical performance of wideband flip-chip transition

Abstract: A locally matching technique is proposed in this paper to improve the wideband performance of the flip-chip transition. The gap width of the coplanar waveguide (CPW) line in the bump pad region of both the chip and board is enlarged for achieving larger inductance to compensate the capacitance at the transition, making the approximate impedance close to 50 /spl Omega/. An equivalent circuit is derived from the frequency response of the transition simulated by Sonnet and is used to control the zero frequency of the structure. With a properly chosen value of the enlarged width, the zero frequency can be controlled to achieve an optimal transition performance over an as wide as possible bandwidth. A systematic design procedure is established and employed to design a transition over a band from dc to 60 GHz. The design and simulation results are also compared with the measured data of a scaled structure as well as a realization of an optimized flip-chip transition design ranging from dc to Ka band. The measured data show a good agreement with the simulation results, if under a careful calibration procedure. Both demonstrate that the present transition design can achieve better than 25 dB in return loss and 0.2 dB in insertion loss over dc to 35 GHz.

2 and 4 watt Ka-band GaAs PHEMT power amplifier MMICs

Abstract: The design and performance of power amplifiers for Ka-band applications is presented. A three-stage amplifier demonstrated 22 dB small signal gain from 26.5 GHz to 31.5 GHz and saturated output power of 4W with 28% power added efficiency from 28 GHz to 31 GHz. Record power density of 670 mW per mm of device output periphery was achieved. The amplifiers were fabricated on a selective double-recess 0.2 /spl mu/m GaAs power pHEMT process.

A compact and low-phase-noise Ka-band pHEMT-based VCO

Abstract: A low phase-noise Ka-band monolithic voltage-controlled oscillator (VCO) designed using the negative resistance concept is reported. A circuit fabricated using the three-dimensional monolithic microwave integrated circuit technology exhibits a high integration level; its size is a record at just 0.5 mm/sup 2/. On-wafer measurements demonstrate a low phase noise of -102 dBc/Hz at a 1-MHz offset. The VCO delivers an output power of 11.8 dBm at the center frequency of 28.3 GHz. The frequency tuning range is more than 3.8 GHz. Dependence of the circuit performance on the bias conditions is also reported and suggests that an optimum phase-noise characteristic can be achieved when biasing the transistor to optimize its transconductance and noise figure.

Modeling of apparent radar reflectivity due to convective clouds at attenuating wavelengths

Abstract: [1] Spaceborne precipitation radars are usually designed to operate at attenuating wavelengths, mostly at X, Ku and Ka band. At these frequencies and above, convective rainfall can cause severe attenuation. Moreover, raindrops and precipitating ice can give rise to appreciable multiple scattered radiation which apparently tends to enhance the nominal attenuated reflectivity. In order to properly describe radar observations in such conditions, apparent reflectivity has to be modeled taking into account both path attenuation and incoherent effects. To this aim, a general definition of volume radar reflectivity is introduced, and a Monte Carlo model of backscattered specific intensity is implemented. The numerical model is applied to synthetic profiles, extracted from a mesoscale cloud-resolving model simulation and representing intense and heavy convective precipitation at a developing and mature stage. Realistic appearance of these average profiles is argued by resorting to radar measurements available in literature. Spaceborne apparent reflectivity due to multiple scattering is shown to be significantly different from the attenuated one for the near-surface layers of mature convection at Ku band and even for growing convection at Ka band. A discussion about this discrepancy is carried out at Ku band showing its possible impact for estimated rain rate profiles. If precipitation incoherent effects are formally treated as perturbation factors of the specific attenuation model, constrained single-frequency inversion techniques are shown to be suitable to minimize rain rate retrieval errors due to multiple scattering phenomenon.

Modelling of nonlinear distortion in broadband fixed wireless access systems

Abstract: A new functional model is presented for the accurate modelling of Ka-band solid state power amplifier (SSPA) nonlinearities. The model is shown to describe the AM/AM characteristics of several 28 GHz SSPAs more accurately than existing models such as those of Saleh, Ghorbani and Rapp [1981 and 1991].

Global mapping of attenuation at Ku- and Ka-band

Abstract: The propagation of radio waves for Earth-space slant path at C-band and higher frequencies is dominated by precipitation in the atmosphere. At a given frequency, attenuation depends on the length of the radio path, the size distribution, and the phase state of the hydrometeor profile. Using the observations from the Tropical Rainfall Measuring Mission (TRMM) spaceborne Ku-band (13.8 GHz) radar at low Earth orbit of 350 km above Earth, global attenuation maps are produced at the Ku-band frequency. A simple microphysical model for precipitation developed using hydrometeor size distributions and thermodynamic phase state is used to estimate attenuation and reflectivity observations at Ka-band (35 GHz) where numerous high-bandwidth satellite applications are being planned including the next-generation space-based radar for the Global Precipitation Mission (GPM). Differences in the microphysical structure in convective and stratiform precipitation are also incorporated in the model. The results show substantial attenuation variation in a 12-month period at both Ku- and Ka-bands over the various regions of the globe, including the contrast between land and ocean. The estimates of attenuation made at Ku- and Ka-band will be useful in the design and development of spaceborne systems.

A dual-band reflectarray for X- and Ka-bands

Abstract: The main benefits of Ka-band communication systems are faster'data rates and smaller antennas (for a given directivity). The biggest disadvantage of communication at Ka-band, of course, is significantly higher loss. Inflatable structures offer a large, lightweight aperture that can be stowed in a small volume for launch. Reflectarray antennas offer a flat antenna geometry, which can be integrated more readily with inflatable deployment mechanisms than other curved surfaces. The combination of these two technologies would allow for smaller and lighter spacecraft designs, which would also reduce launch costs.

Circuit analysis of Ka-band extended interaction klystron

Abstract: In this article, we explained about the design of extended interaction klystron. On account of increased circuit losses at millimeter wavelength, extended interaction klystron, EIK, which consists of a slow wave structure in each single cavity, is motivated. In order to estimate the performance of an optimized circuit, Wessel-Berg's space charge wave theory (WBA) is employed. In this procedure HFSS are directly applied to WBA. A one-dimensional disk-model simulation code, JPNDISK is also employed.

All-planar dual-mode asymmetric filters at Ka-band

Abstract: All-planar dual-mode inductive asymmetric filters utilizing new planar microstrip to dielectric-loaded rectangular waveguide transitions at Ka-band were presented and built in this work. The conventional, three-dimensional metallic rectangular waveguide dual-mode filters can be implemented into mature PCB technology with a much easier and lower-cost fabrication process on the basis of the all-planar feature of the transition. This work demonstrates two Ka-band filter examples with center frequency at 31 GHz and bandwidth at 1 GHz and 2 GHz. The measured minimum insertion loss of each case was, respectively, 2.68 and 1.12 dB, with greater than 10 dB return loss in the passband. Moreover, the measured side-band attenuation (near passband) is larger than 30 dB due to the transmission zeros at each side of the passband.

New dielectric-covered waveguide-to-microstrip transitions for Ka-band transceivers

Abstract: New dielectric-covered waveguide-to-microstrip transitions at Ka-band have been developed. These transitions are probe-type, but the dielectric material completely covers the waveguide opening in order to provide a moisture barrier and robustness. These transitions are also designed to be less sensitive to fabrication tolerances. The transition structures have been comprehensively analyzed using a 3-D EM software. The resonance phenomena caused by the waveguide-wall discontinuity have been removed by placing vias around the waveguide aperture. These transitions have also been fabricated and measured. The measured insertion loss of the transition is less than 0.4 dB and the return loss is about 15 dB over the entire Ka-band.

A balanced 2 watt compact PHEMT power amplifier MMIC for Ka-band applications

Abstract: A balanced form, compact power amplifier MMIC operating at Ka-band was designed and developed using TriQuint's 3MI 0.25/spl mu/m gate length pHEMT technology. This balanced three-stage power amplifier, with chip size of 6.16mm/sup 2/ (2.8/spl times/2.2mm), on 100/spl mu/m GaAs substrate achieved 32.8dBm (1.9Watt) P/sub 1dB/ output power and saturated output power above 2 Watts with higher small signal gain than 18dB at 30GHz. This chip provides a high power and low cost benchmark solution for Ka-band radio market.

High dynamic range, triple gate-based compact DC-40 GHz variable attenuator MMIC for Ka-band variable gain amplifier ICs

Abstract: The design and performance of a compact DC-40 GHz variable attenuator MMIC are reported in this paper Using our standard 4-inch 025-/spl mu/m GaAs power PHEMT technology, this T-type attenuator exhibits more than 30-dB dynamic range, with a nominal insertion loss of 4 dB over the DC-40 GHz band By using triple-gate FETs, typical input power compression of more than 10 to 20 dBm is achieved with a die area of only 1 mm/sup 2/ (09/spl times/112 mm/sup 2/) and better overall performance This MMIC is 30% smaller than any previously reported analog attenuators operating in the DC-40 GHz frequency range This attenuator is used as well in a variable gain amplifier (VGA), specifically designed for Ka-band LMDS and VSAT radios From 24 to 32 GHz, the VGA MMIC demonstrates a maximum gain of 32 dB, with more than 35-dB dynamic range and 24-dBm output power at 1-dB gain compression

A Ka-band class F MMIC amplifier design utilizing adaptable knowledge-based neural network modeling techniques

Abstract: This paper describes the first implementation of an adaptable knowledge-based neural network (AKBNN) model in a high efficiency class F MMIC (monolithic microwave integrated circuit) amplifier design at Ka-band in a 0.25 /spl mu/m GaAs PHEMT technology. A single-stage amplifier based upon the AKBNN model employed shows comparable results to measured performance of a gain of 7.5 dB, a PAE of 35%, and an output power of 17 dBm.

Fully terminated Ka band high isolation, high power MMIC SPDT switch in GaAs PIN technology

Abstract: In this paper we present the design and performance of a millimeter wave MMIC SPDT switch. The switch is produced in a GaAs PIN process. The switch is fully terminated in all 3 ports due to an integrated resistor layer in the PIN process, and has an OFF state. The isolation is better than 40 db, return loss better than 20 db in all states. The power handling capability exceeds 5 watt. To our best knowledge, this is the first reported millimeter wave switch to possess all of the above properties.

Design of Ka band highly selective wideband band-pass filters using directly coupled resonant irises

Abstract: This paper presents the design of a class of high frequency wideband band-pass filters with high selectivity in waveguide technology. The structure of the band-pass filter is a directly coupled one, i.e., the electromagnetic energy propagates through only one path, so that each resonator is coupled to the previous resonator (or the input) and the following resonator (or the output), without cross couplings between them. The resonators of the filter are resonant irises, while the coupling between resonators is obtained through quarter-wavelength waveguide sections. The paper describes a systematic procedure for the design of such filters using the mode matching method. Results for Ka band satellite communication applications are shown and excellent performances are obtained.

Feasibility Study on Acquisition, Tracking, and Pointing Using Earth Thermal Images for Deep-Space Ka-Band and Optical Communications

Abstract: The feasibility of using long-wavelength Earth thermal (infrared) images for antenna/telescope tracking/pointing applications for both deep-space Ka-band (18 to 35 GHz) and free-space optical communications has been investigated and is reported on here. The advantage of this technology rests on using full Earth images in this band that yield more accurate estimates of geometric centroids than those of Earth images in the visible band. Furthermore, these images are nearly independent of Earth phase angle. The results of the study show that, at a Mars range with currently available sensors, a noise equivalent angle of 10 to 150 nrad and a bias error of better than 80 nrad can be obtained. This would enable precise pointing of both the optical and Ka-band communications beams.

Modified Slot-Loaded Multi-Band Microstrip Patch Antenna

Abstract: In this paper, a triple-band planar antenna is proposed for the application to miniaturized automobile safety devices operating at X band(10.5 GHz), K band(24.15 GHz), and Ka band(34.3 GHz). The frequency ratio between the resonant frequencies of this antenna can be adjusted from 1.99 to 2.23 for both X band and K band by varying its slit length. Parasitic elements are added on the modified slot loaded antenna to obtain the third resonance. From numerical as well as experimental results, it has been confirmed that this type of antenna is appropriate for planar multi-band antenna systems.

Design of Ka-band Satellite Ground Station Antenna/RF System

Abstract: This paper describes the design of the Ka-band Antenna/RF system, which was developed for the experiment of the high-speed satellite communications with geostationary satellite. The design issues described here are the ka-band characteristics for having an optimum performance. and the system characteristic for having a reliable and an extensional operation.

LTCC-Technology for Miniaturised Ka-Band Frontends

Abstract: A modern state-of-the-art radar frontend for use in Ka-band radar applications like small seekers for missiles or drones has stringenst requirements to electrical, mechanical and thermal aspects. It has surely also be taken care on economical and environmental demands. This vast array of seemingly contradictory conditions can be fulfilled by using a LTCC-multilayer (Low Temperature Cofired Ceramic). LTCC-technology is one of the most advanced approaches to the miniaturisation of RF circuits.

Small Relay Satellite(s) for Improving the Reactivity of Observation Satellites

Abstract: The study is about a low cost data relay satellites solution, for upgrading the reactivity of earth observation (civil and military) and scientific satellites, in the next decades, and its comparison with a totally ground solution obtained by appropriate number and location of ground stations. A cooperative exploitation of all the earth observation satellites available in Europe after 2010 will provide a good flying frequency capacity over a same site (less than 3h). But this performance, very expensive to achieve because directly linked to the number of satellites, may not be fully exploited because of lack of communication links (scheduling and image data return) and in particular in case of operation theatre. In that case, the following global loop should be minimized : images data return from one satellite, data interpretation, scheduling preparation and telecommand of the following satellite. So the reactivity need is translated in emergency data return need and emergency scheduling need. After this reactivity need analysis, several relay satellites scenario are studied and traded, according to different parameters: the intersatellite links type : RF or optical : the orbit (Medium or geostationary Earth Orbit)), the interest zone (Europe or global earth), the satellite size (micro-satellite, mini-satellite ,else, passenger payload). The relay payload mass is relatively small (#60 kg). The RF option focuses the difficulty on the required antenna size (#2m) for Ka band return link and the S band two ways scheduling link , which leads to study dedicated small satellite solutions. Optical option enables smaller payload and piggybacking approaches provided that the scheduling is also done in the optical spectrum at price of some operational constraints like rendez-vous procedure with LEO (Low Earth Orbit) satellite not required with the S band. .For the terminal on the LEO satellite, the situation is opposite with optical bringing higher accommodation constraints. Other trade-off analysis, like the terminal complexity, lead to recommend interruption of LEO imaging mission during the image return link, which of course bring the interruption duration (typically few minutes per 10 Gbits) within the key performance criterias. A technical (including design and levels of performance) and economic analysis (including development, launch and replacement policy) allow to compare all the satellites solutions and those based on ground stations network.

A new Ka-band microstrip Y-junction circulator with a ferrite sphere

Abstract: A novel microstrip circulator with a magnetized ferrite sphere is proposed for millimetre wave communications. A three-dimensional finite difference time-domain (FDTD) approach for the analysis of this ferrite sphere-based microstrip circulator is presented. The electromagnetic fields inside the ferrite junction are calculated by using special updating equations derived from the equation of motion of the magnetization vector and Maxwell's curl equations in consistency. Frequency-dependent insertion loss, isolation and reflection loss of circulator are calculated over a wide band of frequencies with a single FDTD run. Experimental results at the Ka-band are presented and compared with theoretical simulation. Good agreement is found between them.

Development of a receiver downconverter module for Ka-band satellite payload

Abstract: This paper describes the design and the test results of the receiver-downconverter module for a Ka-band Satellite Payload. The developed module has the low noise amplification in front stage and frequency down conversion which translates from 30.6 GHz - 31.0 GHz to 20.8 GHz - 21.2 GHz.. It has been fabricated and tested by the qualified satellite component manufacturing process and it shows the best performance of the receiver-downconverter modules operating at Ka-band frequency up to date. The module has the performance of 1.9 dB of NF, 55 dB of Gain, and 57 dBc of C/13 for the two-tone signals of -59 dBm input power, respectively, at ambient temperature. It is a small and light module with the size of 93 mm /spl times/ 84 mm /spl times/ 26 mm and the weight of 240 g.

Development of the Microstrip Circulator with a Magnetized Ferrite Sphere in Millimeter Wave Band

Abstract: In this paper, a novel microstrip circulator with a magnetized ferrite sphere is proposed for various millimeter wave communications A three-dimensional Finite-Difference Time-Domain (FDTD) approach for the analysis of this ferrite sphere based microstrip circulator is first presented The electromagnetic fields inside the ferrite junction are calculated using special updating equations derived from the equation of motion of the magnetization vector and Maxwell's curl equations in consistency Frequency dependent insertion loss, isolation and reflection loss of circulator are calculated over a wide band of frequencies with a single FDTD run Experimental results at Ka band are presented and compared with theoretical simulations As a result, a good agreement is found between them

Operational demonstration of ka-band telecommunications for the mays reconnaissance orbiter

Abstract: The objectives of the operational demonstration are to verify that the anticipated benefits of the higher carrier frequency can actually be realized under realistic operating conditions, and if possible to provide a significant enhancement to scientific data return.

New results on MMIC six-port's used in Ka band direct conversion receivers

Abstract: New results obtained on two Ka band Monolithic Microwave Integrated Circuit (MMIC) six-port junction circuits realized in GaAs PHEMT technology at TriQuint Texas Foundry are presented in this paper. Comparative results of simulated and measured S parameters are shown for both designs. The proposed MMIC six-port circuit is used to realize the QPSK demodulator of a Ka band direct conversion receiver.

Micromachined microwave filters

Abstract: Microwave circuits in the millimetre wave region demand low loss, and low dispersion transmission lines. The work carried out in this thesis is on low loss transmission lines and filters, based on a square coaxial transmission line which is made only of metal, avoiding dielectric and radiation losses. The metal structure inside the square coaxial transmission line is supported by stubs, which provide the mechanical support for the centre conductor for the coaxial transmission lines and filters. The coaxial structure is made by stacking thick planar layers of material to suit microfabrication, providing the means to design high Q Microwave and RF passive devices, this transmission line structure is compact compared with a microstrip or a stripline, and gives better loss performance. Through this thesis, the way of optimising the square coaxial transmission line to provide a low loss will be presented, which will end in the presentation of one dielectric supported coaxial structure and three self supported filters, three of them were designed for the X-band, and one of them was designed for the Ka band. The application of the coaxial transmission line is demonstrated with wideband and narrow band designs.

Very low noise Ka-Band oscillator in LTCC technology

Abstract: In this paper a Ka-Band oscillator exhibiting single sideband phase noise below ?150 dBc/Hz at 10 MHz offset from the carrier is described. The oscillating frequency in the range 26-40 GHz is determined by the dimensions of an externally attached cavity. All electronic components including the MMICs are placed on a low temperature cofired ceramic (LTCC) substrate. A metallised liquid crystal polymer (LCP) cover is soldered on the substrate, thus providing a hermetic sealing of the millimetre wave MMICs.