Showing papers on "Microstrip published in 2001"

Microstrip filters for RF/microwave applications

Abstract: Preface to the Second Edition. Preface to the First Edition. 1 Introduction. 2 Network Analysis. 2.1 Network Variables. 2.2 Scattering Parameters. 2.3 Short-Circuit Admittance Parameters. 2.4 Open-Circuit Impedance Parameters. 2.5 ABCD Parameters. 2.6 Transmission-Line Networks. 2.7 Network Connections. 2.8 Network Parameter Conversions. 2.9 Symmetrical Network Analysis. 2.10 Multiport Networks. 2.11 Equivalent and Dual Network. 2.12 Multimode Networks. 3 Basic Concepts and Theories of Filters. 3.1 Transfer Functions. 3.2 Lowpass Prototype Filters and Elements. 3.3 Frequency and Element Transformations. 3.4 Immittance Inverters. 3.5 Richards' Transformation and Kuroda Identities. 3.6 Dissipation and Unloaded Quality Factor. 4 Transmission Lines and Components. 4.1 Microstrip Lines. 4.2 Coupled Lines. 4.3 Discontinuities and Components. 4.4 Other Types of Microstrip Lines. 4.5 Coplanar Waveguide (CPW). 4.6 Slotlines. 5 Lowpass and Bandpass Filters. 5.1 Lowpass Filters. 5.2 Bandpass Filters. 6 Highpass and Bandstop Filters. 6.1 Highpass Filters. 6.2 Bandstop Filters. 7 Coupled-Resonator Circuits. 7.1 General Coupling Matrix for Coupled-Resonator Filters. 7.2 General Theory of Couplings. 7.3 General Formulation for Extracting Coupling Coefficient k. 7.4 Formulation for Extracting External Quality Factor Qe. 7.5 Numerical Examples. 7.6 General Coupling Matrix Including Source and Load. 8 CAD for Low-Cost and High-Volume Production. 8.1 Computer-Aided Design (CAD) Tools. 8.2 Computer-Aided Analysis (CAA). 8.3 Filter Synthesis by Optimization. 8.4 CAD Examples. 9 Advanced RF/Microwave Filters. 9.1 Selective Filters with a Single Pair of Transmission Zeros. 9.2 Cascaded Quadruplet (CQ) Filters. 9.3 Trisection and Cascaded Trisection (CT) Filters. 9.4 Advanced Filters with Transmission-Line Inserted Inverters. 9.5 Linear-Phase Filters. 9.6 Extracted Pole Filters. 9.7 Canonical Filters. 9.8 Multiband Filters. 10 Compact Filters and Filter Miniaturization. 10.1 Miniature Open-Loop and Hairpin Resonator Filters. 10.2 Slow-Wave Resonator Filters. 10.3 Miniature Dual-Mode Resonator Filters. 10.4 Lumped-Element Filters. 10.5 Miniature Filters Using High Dielectric-Constant Substrates. 10.6 Multilayer Filters. 11 Superconducting Filters. 11.1 High-Temperature Superconducting (HTS) Materials. 11.2 HTS Filters for Mobile Communications. 11.3 HTS Filters for Satellite Communications. 11.4 HTS Filters for Radio Astronomy and Radar. 11.5 High-Power HTS Filters. 11.6 Cryogenic Package. 12 Ultra-Wideband (UWB) Filters. 12.1 UWB Filters with Short-Circuited Stubs. 12.2 UWB-Coupled Resonator Filters. 12.3 Quasilumped Element UWB Filters. 12.4 UWB Filters Using Cascaded Miniature High- And Lowpass Filters. 12.5 UWB Filters with Notch Band(s). 13 Tunable and Reconfigurable Filters. 13.1 Tunable Combline Filters. 13.2 Tunable Open-Loop Filters without Via-Hole Grounding. 13.3 Reconfigurable Dual-Mode Bandpass Filters. 13.4 Wideband Filters with Reconfigurable Bandwidth. 13.5 Reconfigurable UWB Filters. 13.6 RF MEMS Reconfigurable Filters. 13.7 Piezoelectric Transducer Tunable Filters. 13.8 Ferroelectric Tunable Filters. Appendix: Useful Constants and Data. A.1 Physical Constants. A.2 Conductivity of Metals at 25 C (298K). A.3 Electical Resistivity rho in 10-8 m of Metals. A.4 Properties of Dielectric Substrates. Index.

Integrated microstrip and rectangular waveguide in planar form

Abstract: Usually transitions from microstrip line to rectangular waveguide are made with three-dimensional complex mounting structures. In this paper, a new planar platform is developed in which the microstrip line and rectangular waveguide are fully integrated on the same substrate, and they are interconnected via a simple taper. Our experiments at 28 GHz show that an effective bandwidth of 12% at 20 dB return loss is obtained with an in-band insertion loss better than 0.3 dB. The new transition allows a complete integration of waveguide components on substrate with MICs and MMICs.

A design of the low-pass filter using the novel microstrip defected ground structure

Abstract: A new defected ground structure (DGS) for the microstrip line is proposed in this paper. The proposed DGS unit structure can provide the bandgap characteristic in some frequency bands with only one or more unit lattices. The equivalent circuit for the proposed defected ground unit structure is derived by means of three-dimensional field analysis methods. The equivalent-circuit parameters are extracted by using a simple circuit analysis method. By employing the extracted parameters and circuit analysis theory, the bandgap effect for the provided defected ground unit structure can be explained. By using the derived and extracted equivalent circuit and parameters, the low-pass filters are designed and implemented. The experimental results show excellent agreement with theoretical results and the validity of the modeling method for the proposed defected ground unit structure.

Bandwidth enhancement of a microstrip-line-fed printed wide-slot antenna

Abstract: Printed wide-slot antennas fed by a microstrip line with a fork-like tuning stub for bandwidth enhancement are proposed and experimentally investigated. Both the impedance and radiation characteristics of this antenna are studied. Experimental results indicate that a 1:1.5 VSWR bandwidth of 1 GHz is achieved at operating frequencies around 2 GHz, which is nearly ten times that of a conventional microstrip-line-fed printed wide-slot antenna. It also achieved a 2-dB gain bandwidth of at least 0.5 GHz.

New microstrip "Wiggly-Line" filters with spurious passband suppression

Abstract: In this paper, we present a new parallel-coupled-line microstrip bandpass filter with suppressed spurious passband. Using a continuous perturbation of the width of the coupled lines following a sinusoidal law, the wave impedance is modulated so that the harmonic passband of the filter is rejected while the desired passband response is maintained virtually unaltered. This strip-width perturbation does not require the filter parameters to be recalculated and, this way, the classical design methodology for coupled-line microstrip filters can still be used. At the same time, the fabrication of the resulting filter layout does not involve more difficulties than those for typical coupled-line microstrip filters. To test this novel technique, 3rd-order Butterworth bandpass filters have been designed at 2.5 GHz, with a 10% fractional bandwidth and different values of the perturbation amplitude. It is shown that for a 47.5 % sinusoidal variation of the nominal strip width, a harmonic rejection of more than 40 dB is achieved in measurement while the passband at 2.5 GHz is almost unaltered.

Novel compact circularly polarized square microstrip antenna

Abstract: A novel compact circular-polarization (CP) operation of the square microstrip antenna with four slits and a pair of truncated corners is proposed and investigated. Experimental results show that the proposed compact CP design can have an antenna-size reduction of about 36% as compared to the conventional corner-truncated square microstrip antenna at a given operating frequency. Also, the required size of the truncated corners for CP operation is much greater than that for the conventional CP design using a simple square microstrip patch, providing a relaxed manufacturing tolerance for the proposed compact CP design. Details of the experimental results are presented and discussed.

Waveguide to microstrip transition

Abstract: A waveguide to microstrip T-junction includes a microstrip transmission line structure having a ground plane separated from a strip conductor by a dielectric layer, the ground plane defining an aperture; a waveguide channel having a conductive periphery being electrically coupled to the ground plane to provide a waveguide short circuit wall located at the end of the waveguide channel; at least one conducting ridge inside the waveguide channel; and an end of the ridge being electrically coupled with the ground plane.

A 4.1 unequal Wilkinson power divider

Abstract: This letter presents the design and measured performances of a microstrip 4:1 unequal Wilkinson power divider. The divider is designed using the conventional Wilkinson topology with the defected ground structure (DGS). The DGS on the ground plane provides an additional effective inductive component to the microstrip line. This enables the microstrip line to be realized with very high impedance of over 150 /spl Omega/. By employing the DGS to the unequal Wilkinson topology, 4:1 power dividing ratio can be obtained easily without any problem in realization, while it has been impractical to fabricate a 4:1 divider using the conventional microstrip line because of very thin conductor width and extremely low aspect ratio (W/H). As an example, a 4:1 divider has been designed and measured at 1.5 GHz in order to show the validity of the proposed DGS and unequal divider. The measured performances of the 4:1 unequal power divider well agree with the exactly same dividing ratio as that expected.

Analysis and design of impedance-transforming planar Marchand baluns

Abstract: A technique for designing impedance-transforming baluns is presented in this paper. It is based on the Marchand balun with two identical coupled lines. By varying the coupling factor of the coupled sections, a wide range of impedance transforming ratios can be achieved. In addition, a resistive network added between the balun outputs is proposed to achieve balun output matching and isolation. Microstrip baluns, matched at all ports, for transforming from a 50-/spl Omega/ source impedance to 40-/spl Omega/ as well as 160-/spl Omega/ load terminations are realized to demonstrate the technique.

Microstrip RF surface coil design for extremely high-field MRI and spectroscopy.

Abstract: A new type of high-frequency RF surface coil was developed for in vivo proton or other nuclei NMR applications at 7T. This is a purely distributed-element and transmission line design. The coil consists of a thin strip conductor (copper or silver) and a ground plane separated by a low-loss dielectric material with a thickness (H). Due to its specific semi-open transmission line structure, substantial electromagnetic energy is stored in the dielectric material between the thin conductor and the ground plane, which results in a reduced radiation loss and a reduced perturbation of sample loading to the RF coil compared to conventional surface coils. The coil is characterized by a high Q factor, no RF shielding, small physical coil size, lower cost, and easy fabrication. A brief theoretical description of the microstrip RF coil is given that can be used to guide the coil designs. A set of gradient-recalled echo images were acquired by using the single- and two-turn microstrip RF surface coils from both phantom and human brain at 7T, which show good penetration and sensitivity. The two-turn coil design significantly improves the B1 symmetry as predicted by the microstrip theory. The optimum H for microstrip surface coils is approximately 7 mm. This coil geometry yields a B1 penetration similar to that of conventional surface coils. SNR comparison was made between the microstrip coil and conventional surface coils with and without RF shielding. The results reveal that the novel surface coil design based on the microstrip concept makes very high-field MRI/MRS more convenient and efficient in research and future clinics.

A compact manufacturable 76-77-GHz radar module for commercial ACC applications

Abstract: The design and measured results of a single-substrate transceiver module suitable for 76-77-GHz pulsed-Doppler radar applications are presented. Emphasis on ease of manufacture and cost reduction of commercial millimeter-wave systems is employed throughout as a design parameter. The importance of using predictive modeling techniques in understanding the robustness of the circuit design is stressed. Manufacturing techniques that conform to standard high-volume assembly constraints have been used. The packaged transceiver module, including three waveguide ports and intermediate-frequency output, measures 20 mm/spl times/22 mm/spl times/8 mm. The circuit is implemented using discrete GaAs/AlGaAs pseudomorphic high electron mobility transistors (pHEMTs), GaAs Schottky diodes, and varactor diodes, as well as GaAs p-i-n and pHEMT monolithic microwave integrated circuits mounted on a low-cost 127-/spl mu/m-thick glass substrate. A novel microstrip-to-waveguide transition is described to transform the planar microstrip signal into the waveguide launch. The module is integrated with a quasi-optical antenna. The measured performance of both the component parts and the complete radar transceiver module is described.

MEM relay for reconfigurable RF circuits

Abstract: We describe a microelectromechanical (MEM) relay technology for high-performance reconfigurable RF circuits. This microrelay, fabricated using surface micromachining, is a metal contact relay with electrical isolation between signal and drive lines. This relay provides excellent switching performance over a broad frequency band (insertion loss of 0.1 dB and isolation of 30 dB at 40 GHz), versatility in switch circuit configurations (microstrip and coplanar, shunt and series), and the capability for monolithic integration with high-frequency electronics. In addition, this MEM relay technology has demonstrated yields and lifetimes that are promising for RF circuit implementation.

MEMS-switched reconfigurable antennas

Abstract: The integration and use of RF MEMS switches in microstrip patch antennas and feed structures were investigated for developing reconfigurable multi-band antennas. The current application focuses on the development of a dual L/X-band antenna that would support several satellite or UAV-based communications and radar applications such as SAR, terrain mapping, GMTI, AMTI, etc. A reconfigurable patch module (RPM) was designed and fabricated consisting of a 3/spl times/3 array of patches connected together using MEMS switches (we simulated MEMS switches with ideal OPEN/CLOSED switches). This RPM could be used as a basic element in a tile/conformal architecture. Stripline power dividers and blind via transitions were developed to demonstrate feed structures that could be located below the radiating aperture.

The dependence of the input impedance on feed position of probe and microstrip line-fed patch antennas

Abstract: The impedance of a rectangular patch antenna fed by an inset microstrip transmission line was measured for various feed positions. The dependence found was then compared to theoretical predictions both for this geometry and for the similar case of an inset coaxial probe feed.

Hybrid resonator microstrip line filters

Abstract: An electronic filter includes a substrate, a ground conductor, a plurality of linear microstrips positioned on a the substrate with each having a first and connected to the ground conductor. A capacitor is connected between a second end of the each of the linear microstrips and the ground conductor. A U-shaped microstrip is positioned adjacent the linear microstrips, with the U-shaped microstrip including first and second extentions positioned parallel to the linear microstrips. Additional capacitors are connected between a first end of the first extention of the U-shaped microstrip and the ground conductor, and between a first end extention of the U-shaped microstrip and the ground conductor. Additional U-shaped microstrips can be included. An input can coupled to one of the linear microstrips or to one of the extentions of the U-shaped microstrips. An output can be coupled to another one of the linear microstrips or to another extention of one of the U-shaped microstrips. The capacitors can be voltage tunable dielectric capacitors.

A power amplifier with efficiency improved using defected ground structure

Abstract: The authors report the effects of defected ground structure (DGS) on the output power and efficiency of a class-A power amplifier. In order to evaluate the effects of DGS on the efficiency and output power, two class-A GaAs FET amplifiers have been measured at 4.3/spl sim/4.7 GHz. One of them has a 50 /spl Omega/ microstrip line with DGS at the output section, while the other has only 50 /spl Omega/ straight line. It is shown that DGS rejects the second harmonic at the output and yields improved output power and power added efficiency by 1/spl sim/5%.

Radio communication device with integrated antenna, transmitter, and receiver

Abstract: First to third dielectric layers (201-203) are deposited to form a multilayered dielectric substrate (220). A plurality of conductor patches (204a-204d) are formed on the surface of the first dielectric layer (201). An antenna-feeding microstrip line (205) is formed between the first and second dielectric layers. A ground layer (206) is formed between the second and third dielectric layers (202, 203). Microstrip lines (208a, 208b) for high-frequency circuits are formed on the back of the third dielectric layer (203). The ground layer (206) has a slot (207) though which the antenna-feeding microstrip line (205) and the high-frequency microstrip line (208a) are coupled electromagnetically. Thus, the efficiency and directivity of an antenna are improved.

Model of thin-film microstrip line for circuit design

Abstract: An equivalent-circuit model for the thin-film microstrip line (TFMSL) is presented in this paper. Its elements are calculated using closed-form expressions and, thus, this model can easily be implemented in common circuit design tools. For typical TFMSL dimensions, it holds from DC up to the submillimeter-wave frequency range. The model is validated by comparison to electromagnetic full-wave simulation data. Typical errors of phase constant and characteristic impedance are below 2% and 3%, respectively. Regarding attenuation, deviations below 8% are found.

Compact reflective-type phase-shifter MMIC for C-band using a lumped-element coupler

Abstract: The design and results of an ultra-compact single-load reflective-type monolithic-microwave integrated-circuit phase shifter at 6.2 GHz for a satellite radar system is presented in this paper, which has been fabricated using a commercial 0.6-/spl mu/m GaAs MESFET process. A 3-dB 90/spl deg/ coupler with lumped elements enables significant circuit size reduction in comparison to former approaches applying microstrip branch line or Lange couplers. Phase control is enabled using MESFET varactors with capacitance control ratios (C/sub max//C/sub min/) of only four. Equations are derived to precisely describe the phase control ranges versus capacitance control ratios for different load configurations to allow efficient optimizations. Furthermore, the design tradeoff between low loss and high phase control range is discussed. Within a phase control range of 210/spl deg/, a loss of 4.9 dB/spl plusmn/0.9 dB and a 1-dB input compression point of higher than 5 dBm was measured for the designed phase shifter. The circuit size is less than 0.5 mm/sup 2/, which, to our knowledge, is the smallest reflective-type phase-shifter size reported to date.

Wide-band low-loss high-isolation microstrip periodic-stub diplexer for multiple-frequency applications

Abstract: This paper introduces a three-port microstrip multifrequency diplexer used in a phased-array transceiver system that employs band-stop filters with open-circuited stubs for band selection and separation. The diplexer is designed to take 10, 12, 19, and 21 GHz into port 1 and to separate 10 and 19 GHz to port 2 and 12 and 21 GHz to part 3 with minimal dispersion. The insertion loss for each frequency varies from 0.4 to 3.4 db and the return loss is better than 10 dB. The isolation between channels at the four frequencies is greater than 50 dB. Each passband created between adjacent stopbands has a bandwidth over 1 GHz. The microstrip diplexer is designed using periodic stubs that collectively have the advantages of low insertion loss, high isolation and rejection, wide-band performance on each channel, and easy fabrication. This type of diplexer has many applications in multifrequency transceivers for communication systems.

Power-amplifier modules covering 70-113 GHz using MMICs

Abstract: A set of W-band power amplifier (PA) modules using monolithic microwave integrated circuits (MMICs) have been developed for the local oscillators of the far-infrared and sub-millimeter telescope (FIRST). The MMIC PA chips include three driver and three PAs, designed using microstrip lines, and another two smaller driver amplifiers using coplanar waveguides, covering the entire W-band. The highest frequency PA, which covers 100-113 GHz, has a peak power of greater than 250 mW (25 dBm) at 105 GHz, which is the best output power performance for a monolithic amplifier above 100 GHz to date. These monolithic PA chips are fabricated using 0.1-/spl mu/m AlGaAs/InGaAs/GaAs pseudomorphic T-gate power high electron-mobility transistors on a 2-mil GaAs substrate. The module assembly and testing, together with the system applications, is also addressed in this paper.

Transmission-line load-network topology for class-E power amplifiers

Abstract: Class-E amplifiers are a type of switching amplifier offering very high efficiency approaching 100%. In this paper, a topology and design methodology, which could be used for a transmission-line implementation of a class-E power amplifier, is presented. A simple transmission-line class-E load network is proposed that offers combined transformation of the load resistance down to a suitable level, as well as simultaneous suppression of harmonics in the load. The load network was developed and tested with the aid of a time-domain simulator (i.e., SPICE). A microstrip layout was designed and a first prototype was built operating at 1 GHz utilizing a field-effect transistor as the switching device. A drain efficiency of 72% was measured for our prototype after tuning, although better performance can be expected with an improved switching transistor and careful tuning of the load network.

Dual polarization stacked microstrip patch antenna array with very low cross-polarization

Abstract: This paper describes the development and performance of a wideband dual linear polarization microstrip antenna array used in the Danish high-resolution airborne multifrequency polarimetric synthetic aperture radar, EMISAR. The antenna was designed for an operating frequency of 1.25 GHz/spl plusmn/50 MHz and was built as an array of 8/spl times/2 probe-fed stacked microstrip patches. The feeding network is constructed in microstrip and is capable of handling 6 kW of peak input-power at an altitude of 45000 ft (unpressurized). The impedance bandwidth (return loss better than -14 dB) of the antenna is 10%, the isolation between the horizontal and the vertical ports of the array is 50 dB and the cross-polarization suppression is 40 dB. A new design principle for simultaneously achieving very low cross-polarization and low side lobes in dual linear polarization antenna arrays has been applied.

Real-Time Spectrum Analysis in Microstrip Technology

Abstract: We report on a time-domain analog to the spatial far-field Fraunhofer diffraction using microstrip lines with chirped distributed Bragg coupling between the fundamental microstrip mode and the same but counter-propagating mode. The chirping of the microstrip impedance yields to linear group delays within the reflected bandwidth. Under the condition of a temporal equivalent of the spatial Fraunhofer inequality, the distortion of a frequency-limited pulse results in an output reflected signal whose complex envelope is, except a phase factor, proportional to the Fourier Transform of the input pulse envelope. This has important temporal applications and, in particular, the devices designed in this paper work as real-time energy spectral density analyzers.

Empirical equations on electrical parameters of coupled microstrip lines for crosstalk estimation in printed circuit board

Abstract: Empirical equations for the self and mutual capacitance and inductance (C/sub s/, C/sub m/, L/sub s/, L/sub m/) of coupled microstrip lines in a printed circuit board were derived from the numerical simulation results to reduce the computation time for crosstalk estimation. Comparison of the measured C/sub s/, C/sub m/, L/sub s/ and L/sub m/ values with the derived empirical equations showed good agreements. Also in the near-end and far-end crosstalks, good agreements were obtained between measurements and the derived empirical equations. Microstrip lines embedded in the homogeneous dielectric material as well as those in the inhomogeneous medium with one side exposed to air were considered in this work. Based on the derived empirical equations, a design guide on the spacing between microstrip lines was established.

Novel low-cost ultra-wideband, ultra-short-pulse transmitter with MESFET impulse-shaping circuitry for reduced distortion and improved pulse repetition rate

Abstract: A new ultra-wideband, ultra-short-pulse transmitter has been developed using microstrip lines, step-recovery and Schottky diodes, MESFET, and monolithic microwave integrated circuit (MMIC) amplifier. This transmitter employs a novel MESFET impulse-shaping circuit to achieve several unique advantages, including less distortion, easy broadband matching, and increased pulse repetition rate. The transmitter produces 300-ps monocycle pulses with about 2 V peak-to-peak and a pulse repetition rate of 10 MHz. The measured pulses have good symmetry and low ringing level.

A generalized space-mapping tableau approach to device modeling

Abstract: A comprehensive framework to engineering device modeling, which we call generalized space mapping (GSM) is introduced in this paper. GSM permits many different practical implementations. As a result, the accuracy of available empirical models of microwave devices can be significantly enhanced. We present three fundamental illustrations: a basic space-mapping super model (SMSM), frequency-space-mapping super model (FSMSM) and multiple space mapping (MSM). Two variations of MSM are presented: MSM for device responses and MSM for frequency intervals. We also present novel criteria to discriminate between coarse models of the same device. The SMSM, FSMSM, and MSM concepts have been verified on several modeling problems, typically utilizing a few relevant full-wave electromagnetic simulations. This paper presents four examples: a microstrip line, a microstrip right-angle bend, a microstrip step junction, and a microstrip shaped T-junction, yielding remarkable improvement within regions of interest.

Integrated self-biased hexaferrite microstrip circulators for millimeter-wavelength applications

Abstract: Planar microstrip Y-junction circulators have been fabricated from metallized 130-/spl mu/m-thick self-biased strontium hexaferrite ceramic die, and then bonded onto silicon die to yield integrated circulator circuits. The impedance matching networks needed to transform the low-impedance circulator outputs were deployed on low-loss alumina or glass dielectrics to minimize circuit losses. These magnetically self-biased circulators show a normalized isolation and insertion loss of 33 and 2.8 dB, respectively, and a 1% bandwidth for an isolation of 20 dB. Application of small (H<1.5 kOe) magnetic bias fields improved the isolation and insertion loss values to 50 and 1.6 dB, respectively. This design may form the basis for future monolithic millimeter-wave integrated circulator circuits that do not require magnets.

Control of Attenuation Pole Frequency of a Dual-Mode Microstrip Ring Resonator

Abstract: A novel method is proposed to control the attenuation pole frequency of a dual-mode circular microstrip ring resonator bandpass filter, keeping the bandwidth constant. In this paper, the coupling between the dual modes is provided as the total effect of stub perturbation at the end of symmetry plane, and the angle be- tween input/output ports. By making a various combinations of these two parameters, it is possible to control the attenuation pole frequency. An additional small coupling induced by excitation ca- pacitance is also considered. Filters are simulated using the calcu- lated coupling constant, and then the attenuation pole frequencies and bandwidth of the simulated filters are verified by experiment. Theoretical expressions are further devised to calculate the atten- uation pole frequencies.

The development of inflatable array antennas

Abstract: Inflatable array antennas are being developed to significantly reduce the mass, the launch vehicle stowage volume, and the cost of future spacecraft systems. Three inflatable array antennas, previously developed for spacecraft applications, are a 3.3 m/spl times/1.0 m L-band synthetic-aperture radar (SAR) array, a 1.0 m-diameter X-band telecom reflectarray, and a 3 m-diameter Ka-band telecom reflectarray. All three antennas are similar in construction, and each consists of an inflatable tubular frame that supports and tensions a multi-layer thin-membrane RF radiating surface with printed microstrip patches, The L-band SAR array achieved a bandwidth of 80 MHz, an aperture efficiency of 74%, and a total mass of 15 kg. The X-band reflectarray achieved an aperture efficiency of 37%, good radiation patterns, and a total mass of 1.2 kg (excluding the inflation system). The 3 m Ka-band reflectarray achieved a surface flatness of 0.1 mm RMS, good radiation patterns, and a total mass of 12.8 kg (excluding the inflation system). These antennas demonstrated that inflatable arrays are feasible across the microwave and millimeter-wave spectrum. Further developments of these antennas are deemed necessary, in particular, in the area of qualifying the inflatable structures for space-environment usage.