Theoretical and experimental characterization of nonsymmetricallyshielded coplanar waveguides for millimeter-wave circuits

A quasi-planar structure, the nonsymmetrically shielded coplanar waveguide (NSCPW), is proposed as a quasi-TEM transmission line with advantageous characteristics for millimeter-wave circuit applications. Advantages in terms of broadband behavior and ease of machining, as well as device mounting and substrate mounting, are pointed out. An experimental method is developed which allows the evaluation of the transmission line spectrum in a very wide frequency band (15:1) with a single transmission measurement. The experimentally evaluated propagation characteristics of the dominant and higher order modes are shown to be in excellent agreement with the theoretical predictions based on the generalized transverse resonance technique. This method is also used for an extensive characterization of the structure in terms of characteristic impedance and useful frequency band     

Theoretical and experimental characterization of coplanar waveguidediscontinuities for filter applications

A full-wave analysis of shielded coplanar waveguide (CPW) two-port discontinuities based on the solution of an appropriate surface integral equation in the space domain is presented. Frequency-dependent scattering parameters for open-end and short-end CPW stubs are computed using this method. The numerically derived results are compared with measurements performed in the frequency range 5-25 GHz and show very good agreement. From the scattering parameters, lumped-element equivalent circuits have been derived to model the discontinuities. The inductors and capacitors of these models have been represented by closed-form equations, as functions of the stub length, to compute the circuit element values for these discontinuities     

Theoretical and experimental investigation of millimeter-wave TED's in cross-waveguide oscillators

Theoretical and experimental investigations of millimeterwave GaAs second harmonic transferred electron device (TED) oscillators using separate circuits for frequency and power optimization, are described. The theory predicts the oscillation frequency with less than 2% error for the second harmonic. Apart from the 2d and 3d, a 4'th harmonic from the TED was observed up to 130 GHz.     

Characterization of an experimental ferrite LTCC tape system for microwave and millimeter-wave applications

An experimental-low temperature cofired ceramic (LTCC) ferrite tape system is characterized using circuits that are fabricated from the very material under test. Such in situ circuits provide data that are thought to be more representative of the performance obtainable by more complicated circuitry that will eventually be made from the same material using the same fabrication method. Emphasis is placed on simple measurements that can be performed using a minimum amount of equipment. For the first time, a compact in situ LTCC solenoid transformer is used to measure the magnetostatic properties of the ferrite, yielding a measured saturation flux density of 230 mT, a remanence of 136 mT, and a coercivity of 688 A/m. The peak linear relative permeability of the ferrite is 97 and its Curie temperature is low, only 117/spl deg/C. A novel two-port line-connected ring resonator is used to characterize the material in the 6-40 GHz range. At frequencies above 20 GHz, the relative permittivity of the ferrite is 11.0, whereas its loss tangent ranges from 0.002 to 0.004, demonstrating the ferrite's suitability for use in microwave and millimeter-wave circuitry.     

Quasi-planar filters for millimeter-wave applications

A variety of quasi-planar low-pass, bandpass, and bandstop filters suitable for millimeter-wave applications is reviewed. The emphasis is on ladder-shaped E-plane bandpass filters to highlight their advantages as well as limitations in terms of design, performance, and manufacturing. To extend their range of application it is suggested that E-plane filters be cascaded for better passband separation. A modified finline filter is presented to improve the performance and manufacturing of filters in waveguides below cutoff. It is shown that plated through-holes can simplify filter housing fabrication and that surface-metallized composite housings are a lightweight and low-cost alternative to metal housings     

New devices for millimeter-wave applications

The possibilities for future developments of mm-wave devices are reviewed. New concepts and extensions of presently available devices are considered concerning sources, amplifiers and mixing. We discussed such ideas as micro-cavity triodes unbedded in the semiconductor chip with first experimental evidence available.     

Attenuation mechanisms of aluminum millimeter-wave coplanar waveguides on silicon

The loss mechanisms of silicon coplanar waveguides (CPW) with aluminum metallization are investigated up to 40 GHz. Three main parts contribute to the attenuation of coplanar waveguides (CPWs): the frequency-dependent conductor losses of the metallization, frequency-independent substrate losses, and the specifically investigated bias-dependent interface losses caused by free charges at the Si-SiO/sub 2/ interface. The minimum losses found in 50-/spl Omega/ CPWs with 45-/spl mu/m signal line width were 0.19 db/mm at 10 GHz and 0.33 dB/mm at 40 GHz. High-purity silicon from a float zone (FZ) process was used as substrate. Substrates with lower purity from a Czochralski (CZ) process (resistivity 50-100 /spl Omega/cm) resulted in somewhat higher (0.2-0.3 dB/mm) losses for the same CPW geometry.     

A theoretical and experimental study of coplanar waveguide shuntstubs

A comprehensive theoretical and experimental study of straight and bend coplanar waveguide (CPW) shunt stubs is presented. In the theoretical analysis, the CPW is assumed to be inside a cavity, while, the experiments are performed on open structures. For the analysis of CPW discontinuities with air-bridges, a hybrid technique has been developed which has been validated through extensive theoretical and experimental comparisons. Throughout this study, the effect of the cavity resonances on the behavior of the stubs with and without air-bridges is investigated. In addition, the encountered radiation loss due to the discontinuities is evaluated experimentally     

AlInAs-GaInAs HEMT for microwave and millimeter-wave applications

The status of lattice-matched high-electron-mobility transistors (HEMTs) and pseudomorphic AlInAs-GaInAs grown on In substrates is reviewed. The best lattice-matched devices with 0.1-μm gate length had a transconductance g_m=1080 mS/mm and a unity current gain cutoff frequency f_T=178 GHz, whereas similar pseudomorphic HEMTs had g_m=1160 mS/mm and f_T=210 GHz. Single-stage V-band amplifiers demonstrated 1.3- and 1.5-dB noise figures and 9.5- and 8.0-dB associated gains for the lattice-matched and pseudomorphic HEMTs, respectively. The best performance achieved was a minimum noise figure of F_min=0.8 dB with a small-signal gain of G_a=8.7 dB     

Integrated horn antennas for millimeter-wave applications

This paper reviews the development of integrated horn antennas since their introduction in 1987. The integrated horn is fabricated by suspending a dipole antenna on a thin dielectric membrane in a pyramidal cavity etched in silicon. Recent progress resulted in optimized low and high-gain designs with single and double-polarizations for remote-sensing and communication applications. A fullwave analysis technique have resulted in an integrated antenna with performance comparable to that of waveguide-fed corrugated horn antennas. The integrated horn design can be easily extended to large arrays for imaging and phased array applications while still leaving plenty of room for the rf and w processing circuitry. Theoretical and experimental results at microwave frequencies and at 90, 240 and 802 GHz will be presented.     

Integrated horn antennas for millimeter-wave applications

The development of integrated horn antennas since their introduction in 1987 is reviewed. The integrated horn is fabricated by suspending a dipole antenna, on a thin dielectric membrane, in a pyramidal cavity etched in silicon. Recent progress has resulted in optimized low- and high-gain designs, with single and double polarization for remote-sensing and communication applications. A full-wave analysis technique has resulted in an integrated antenna with performance comparable to that of waveguide-fed corrugated-horn antennas. The integrated horn design can be extended to large arrays, for imaging and phased-array applications, while leaving plenty of room for the RF and IF processing circuitry. Theoretical and experimental results at microwave frequencies and at 90 GHz, 240 GHz, and 802 GHz are presented     

Gate-recessed AlGaN-GaN HEMTs for high-performance millimeter-wave applications

We report deep-submicrometer gate-recessed and field-plated AlGaN-GaN HEMTs and their state-of-the-art continuous wave (CW) power performance measured at 30 GHz. The AlGaN-GaN HEMTs exhibit a CW power density of 5.7 W/mm with a power-added efficiency (PAE) of 45% and drain-efficiency of 58% at V/sub ds/=20 V. At V/sub ds/=28 V, the output power density is measured as high as 6.9 W/mm with both PAE and output power increasing with input power level. Compared to conventional T-gated AlGaN-GaN HEMTs, the output power density and PAE of gate-recessed AlGaN-GaN HFETs are improved greatly, along with the excellent pulsed IVs. We attribute the improvement to both a field-plating effect and a vertical separation of the gate plane from surface states.     

Dielectric rod leaky-wave antennas for millimeter-wave applications

Dielectric rod leaky-wave antennas have the property of being frequency scannable. Bounds are derived for the proper range of spacing of perturbations along the rod to avoid an intrusion upon a grating lobe when frequency scanning. In addition some experimental results are reported on sidelobe levels and polarizations in the far field for these antennas made from a material withepsilon_{r}= 2.33at 81.5 GHz.     

Pillbox antenna design for millimeter-wave base-station applications

A pillbox antenna is a linearly polarized, waveguide-fed, cylindrical reflector, sandwiched between parallel plates. It is well suited to be a base-station antenna for the millimeter-wave, local-to-multipoint distribution service (LMDS). We can form the reflector-surface profile to provide a shaped radiation pattern, such as a cosecant-squared pattern in elevation, and we can design the radiating aperture to provide a broad-beam azimuth pattern. In this article, we begin by discussing LMDS requirements for base-station antennas, and we then briefly compare pillbox antennas with other antennas. Next, we describe in detail a highly accurate and efficient procedure for designing a pillbox antenna, using a combination of ray-tracing theory and commercially available three-dimensional electromagnetic analysis software. In particular, we discuss methods for designing the reflector surface, the waveguide feed horn, the radiating aperture, the polarizer, and the radome. Measured results of a prototype antenna at 29.4 GHz compare very well with our predictions.     

Quantum barrier varactor for coplanar waveguide applications

A quantum barrier varactor with a GaAs/AlGaAs/GaAs structure embedded in a coplanar waveguide has been fabricated. The configuration in the coplanar waveguide improves frequency-tripler performance by using a harmonic load-pull technique     

Planar multimode detector arrays for infrared and millimeter-wave applications

A new type of detector array is described. By means of a suitably designed metallic network, many detector elements (each individually small compared to wavelength) are assembled into an impedance-matched termination for radiation incident normally on the plane of the device. Residual reactance is tuned out by means of a movable backshort. An array of 400 bismuth-film microbolometers with a total area of 1 cm²has been tested at 215 GHz. A coupling efficiency of approximately 60 percent was observed. The detector has aD*of4 times 10^{8}cm . Hz^1/2/W at room temperature with response time on the order of2 times 10^{-7}s. Similar arrays of Schottky and SIS diodes can probably be constructed.     

Leaky CPW-based slot antenna arrays for millimeter-wave applications

A uniplanar leaky-wave antenna (LWA) suitable for operation at millimeter-wave frequencies is introduced. Both unidirectional and bidirectional versions of the antenna are presented. The proposed structure consists of a coplanar waveguide fed linear array of closely spaced capacitive transverse slots. This configuration results in a fast-wave structure in which the n=0 spatial harmonic radiates in the forward direction. Since the distance, d, between adjacent elements of the array is small d/spl Lt//spl lambda//sub o/, the slot array essentially becomes a uniform LWA. A comprehensive transmission line model is developed based upon the theory of truncated periodic transmission lines to explain the operation of the antenna and provide a tool for its design. Measured and simulated radiation patterns, directivity, gain, and an associated loss budget are presented for a 32-element antenna operating at 30 GHz. The uniplanar nature of the structure makes the antenna appropriate for integration of shunt variable capacitors such as diode or micro-electromechanical system varactors for fixed frequency beam steering at low-bias voltages.     

High performance quadruple sub-harmonic mixer for millimeter-wave applications

In this paper, we present high performance quadruple sub-harmonic mixers for millimeter-wave applications. The sub-harmonic mixer was designed by using 0.1 μm GaAs PHEMT's and the coplanar wave-guide library. We show the low conversion loss of 5.8 dB at a local oscillator (LO) power of 13 dBm from the fabricated sub-harmonic mixers. The V-band sub-harmonic mixer also ensure a high degree of isolation showing −75.0 dB in the LO-to-IF and −48.1 dB in the LO-to-RF at a frequency of 14.5 GHz, respectively. The fabricated V-band sub-harmonic mixer has a lower conversion loss characteristics compared with ever reported mixers for millimeter frequencies.