Showing papers on "Ka band published in 2017"

Circularly-Polarized Reconfigurable Transmitarray in Ka-Band With Beam Scanning and Polarization Switching Capabilities

Abstract: The design, realization, and experimental characterization of a 400-element electronically reconfigurable transmitarray operating in the Ka-band is presented. It is based on linearly polarized unit-cells with 180° phase-shifting capability. Several sequential rotation schemes have been compared numerically to generate a circularly polarized beam over a broad frequency band, and a random distribution has been selected to mitigate spurious cross-polarized side-lobes when scanning the main beam. The 2-D electronic beam-steering capabilities of ±60° have been verified experimentally. The prototype, illuminated by a horn antenna as a focal source, exhibits a broadside gain of 20.8 dBi at 29.0 GHz and a 3-dB bandwidth of 14.6% with radiation efficiency of 58%. The axial ratio remains below 2 dB within this bandwidth. Next, a planar substrate integrated waveguide focal source array was designed in order to reduce the focal distance by about 50% and thereby significantly improve the antenna compactness, and similar radiation performance is demonstrated numerically and experimentally. © 1963-2012 IEEE.

Antenna-in-Package Design Considerations for Ka-Band 5G Communication Applications

Abstract: Phased-array modules at frequencies >20 GHz are expected to play an important role for 5G applications. Antenna-in-package (AiP) is a reliable and cost-effective method to realize these phased arrays. This paper introduces a practical Ka-band AiP structure and discusses the antenna element design and implementation tradeoffs. The AiP design is based on multilayer organic buildup substrates that are suitable for phased-array module integration needs and supports both horizontal and vertical polarizations. Measurement results from the fabricated antenna prototypes show 0.8 GHz return loss bandwidth and 3.8-dBi peak gain at 30.5 GHz. Simulation results agree with the measured ones.

High Gain Dual-Band Beam-Steering Transmit Array for Satcom Terminals at Ka-Band

Abstract: Transmit array design is more challenging for dual-band operation than for single band, due to the independent 360° phase wrapping jumps needed at each band when large electrical length compensation is involved. This happens when aiming at large gains, typically above 25 dBi with beam scanning and $F/D \le 1$ . No such designs have been reported in the literature. A general method is presented here to reduce the complexity of dual-band transmit array design, valid for arbitrarily large phase error compensation and any band ratio, using a finite number of different unit cells. The procedure is demonstrated for two offset transmit array implementations operating in circular polarization at 20 GHz(Rx) and 30 GHz(Tx) for Ka-band satellite-on-the-move terminals with mechanical beam-steering. An appropriate set of 30 dual-band unit cells is developed with transmission coefficient greater than −0.9 dB. The full-size transmit array is characterized by full-wave simulation enabling elevation beam scanning over 0°–50° with gains reaching 26 dBi at 20 GHz and 29 dBi at 30 GHz. A smaller prototype was fabricated and measured, showing a measured gain of 24 dBi at 20 GHz and 27 dBi at 30 GHz. In both cases, the beam pointing direction is coincident over the two frequency bands, and thus confirming the proposed design procedure.

Dual-Band Transmitarrays With Dual-Linear Polarization at Ka-Band

Abstract: Dual-band transmitarray antennas are demonstrated at Ka-band with the capability of forming independent linearly polarized beams with a given polarization in each frequency band, while sharing the same radiating aperture. The proposed three-layer unit-cell is based on identical narrow microstrip patches printed on both receiving and transmitting layers and connected by a metallized via hole. The metal layers are printed on two identical substrates bonded with a thin film, and the designed unit-cell exhibits a 180° phase resolution (i.e., 1-b phase quantization). The dual-band dual-polarized property of the transmitarray is achieved by interleaving unit-cells operating in the down-link and up-link frequency bands. Four different prototypes are characterized to demonstrate the relevance of the proposed concepts. A good agreement is obtained between the radiation patterns, gain curves, and cross-polarization levels measured and computed in both frequency bands and polarizations.

A Dual-Band Dual-Circular-Polarization Antenna for Ka-Band Satellite Communications

Abstract: A novel Ka-band dual-band dual-circularly-polarized antenna array is presented in this letter. A dual-band antenna with left-hand circular polarization for the Ka-band downlink frequencies and right-hand circular polarization for the Ka-band uplink frequencies is realized with compact annular ring slots. By applying the sequential rotation technique, a 2 × 2 subarray with good performance is obtained. This letter describes the design process and presents simulation and measurement results.

Ka-Band Linear to Circular Polarization Converter Based on Multilayer Slab With Broadband Performance

Abstract: In this paper, a Ka-band polarization converter is presented, which is based on multilayer slab. In order to improve impedance matching, metallic circular traces are printed periodically on each dielectric multilayer slab. Simulated results of the polarizer show that it can transform linearly polarized (LP) to circularly polarized (CP) fields over a frequency band from 23 to 35GHz (42%) with an insertion loss less than 0.5 dB. The transmitted CP wave by the polarizer is approximately robust under oblique illuminations. The polarizer is fabricated and measured by a wideband horn antenna satisfying the simulated results. Next, in order to design a high-gain CP structure around 30 GHz, an 8-element LP array antenna with Chebyshev tapered distribution is designed and integrated with the polarizer. Obviously, the antenna limits the overall bandwidth (nearly 28 to 31.5 GHz) due to the narrowband nature of the LP antenna array. When the polarizer is illuminated by an incident LP wave, the two linear components of the transmitted wave with approximately equal amplitudes and 90° phase difference on the frequency band of interest are produced. Experimental results of the proposed structure show a pure CP with a gain of 13 dBi at 30 GHz, which can be suitable for millimeter wave communication.

10W power amplifier and 3W transmit/receive module with 3 dB NF in Ka band using a 100nm GaN/Si process

Abstract: This paper presents two Monolithic Microwave Integrated Circuits (MMIC) designed and fabricated with the same 100 nm Gallium Nitride on Silicon (GaN/Si) millimeter wave process, demonstrating the excellent multipurpose capability of this technology. The first circuit is a 29–33 GHz power amplifier, presenting 10 W of output power in pulsed operation and 8 W is CW operation. The second MMIC is a 26–34 GHz Transmit/Receive chip (T/R chip), including on the same chip a Low Noise Amplifier (LNA), a Power Amplifier (PA) and a SPDT switch. In the 28–34 GHz frequency bandwidth, this T/R chip, including the switch losses, presents an output power of 35–36 dBm and a Noise Figure of 2.7 dB with an associated gain of 18 dB for the receive and transmit paths.

Cloud Attenuation Statistics Prediction From Ka -Band to Optical Frequencies: Integrated Liquid Water Content Field Synthesizer

Abstract: The impact of cloud impairments on satellite links is increasing with the employment of higher frequency bands. In this paper, a model for predicting cloud attenuation statistics for satellite communication systems operating from $Ka$ -band to optical range is presented. The cloud attenuation must be accurately quantified for the reliable design of satellite communication systems. A stochastic dynamic model for the generation of integrated liquid water content (ILWC) fields is proposed. The model is based on the stochastic differential equations and incorporates the spatial and temporal behavior of ILWC. Classifying the cloud types based on the cloud vertical extent and using the microphysical properties of clouds, the well-known Mie scattering theory and the global statistics for ILWC by International Telecommunications Union–Radio (ITU-R), a unified space-time model for the prediction of induced attenuation due to clouds for frequencies above $Ka$ -band up to optical range is presented. The proposed model is tested in terms of first order statistics, compared first with ITU-R P.840-6 model and then with data obtained in the literature, showing encouraging results. Moreover, the probability of cloud occurrence for optical satellite single and site diversity system is calculated. Finally, the limitations and the applicability of the proposed model are discussed.

Characterization of Rain Specific Attenuation and Frequency Scaling Method for Satellite Communication in South Korea

Abstract: The attenuation induced by rain is prominent in the satellite communication at Ku and Ka bands. The paper studied the empirical determination of the power law coefficients which support the calculation of specific attenuation from the knowledge of rain rate at Ku and Ka band for Koreasat 6 and COMS1 in South Korea that are based on the three years of measurement. Rain rate data was measured through OTT Parsivel which shows the rain rate of about 50 mm/hr and attenuation of 10.7, 11.6, and 11.3 dB for 12.25, 19.8, and 20.73 GHz, respectively, for 0.01% of the time for the combined values of rain rate and rain attenuation statistics. Comparing with the measured data illustrates the suitability for estimation of signal attenuation in Ku and Ka band whose validation is done through the comparison with prominent rain attenuation models, namely, ITU-R P.618-12 and ITU-R P. 838-3 with the use of empirically determined coefficient sets. The result indicates the significance of the ITU-R recommended regression coefficients of rain specific attenuation. Furthermore, the overview of predicted year-wise rain attenuation estimation for Ka band in the same link as well as different link is studied which is obtained from the ITU-R P. 618-12 frequency scaling method.

A Ka-Band Waveguide Magic-T With Coplanar Arms Using Ridge-Waveguide Transition

Abstract: A Ka-band waveguide magic-T with coplanar arms is presented in this letter. By using an E-plane power divider and a ridge-waveguide transition, the four arms of the magic-T are placed in the same plane, which greatly simplifies the assembly. Compared to the previous method utilizing a microstrip-to-waveguide transition, the structure proposed in this letter achieved a higher power-handling capability because of all-metal elements. Over the frequency band of 28 to 36 GHz, the measured return loss of the input port and the isolation between the opposite ports are greater than 20 dB, indicating good characteristics of the proposed structure.

Thickness and Composition Tailoring of K- and Ka-Band Microwave Absorption of BaCoxTixFe(12−2x)O19 Ferrites

Abstract: The goal of this research is to investigate the electromagnetic and microwave absorption properties of M-type barium hexaferrites with chemical formula BaCo x Ti x Fe(12−2x)O19 (x = 00, 02, 04, 06, 08, 10) in K and Ka band Characterization techniques such as x-ray diffraction analysis and scanning electron microscopy were applied to confirm ferrite formation The frequency dependence of the complex permittivity and complex permeability was studied for prepared ferrite samples in the frequency range from 18 GHz to 40 GHz Factors such as the quarter-wavelength condition, impedance matching, high dielectric–magnetic losses, as well as ferromagnetic resonance were investigated to determine their contribution to the absorption characteristics It was found that the quarter-wavelength (λ/4) model could be successfully applied to predict and understand the position as well as number of reflection peaks in the microwave absorption spectrum The origin of the reflection loss peaks is explained and verified based on calculations of input impedance, loss tangent, and ferromagnetic resonance Reflection loss analysis revealed that all six compositions exhibited reflection loss peaks (absorption >90%) at their matching thicknesses and frequencies Therefore, these ferrites are potential candidates for use in electromagnetic shielding applications requiring low reflectivity in K and Ka band

A CW 20W Ka-band GaN high power MMIC amplifier with a gate pitch designed by using one-finger large signal models

Abstract: This paper reports a 20 W Ka-band GaN high power MMIC (Monolithic Microwave Integrated Circuit) amplifier under continuous wave (CW) operation. The one-finger large signal models were made to take account of both the phase difference of RF gate voltage at a gate feeder and thermal effect. By using this model, the gate pitch length of unit cell transistor was optimally designed to obtain maximum output power as MMIC amplifier under CW operation. As a result, 21.7W output power under CW operation was successfully achieved with power added efficiency (PAE) of 19.8% at Ka-band by a single-ended MMIC. To the best of authors' knowledge, this output power is state-of-the-art for GaN MMIC amplifiers under CW operation at Ka-band.

X/Ka-Band Dual-Polarized Digital Beamforming Synthetic Aperture Radar

Abstract: This paper presents a digital beamforming (DBF) synthetic aperture radar (SAR) for future spaceborne earth observation systems. The objective of the DBF-SAR system is to achieve a low cost, lightweight, low-power consumption, and dual-band (X/Ka) dual-polarized module for the next-generation spaceborne SAR system in Europe. The architectures and modules of the proposed DBF-SAR system are designed according to a realistic mission scenario, which is compatible with the future small/microsatellites platforms. This system fills an important gap in the conception of the future DBF-SAR, facilitating a high level of integration and complexity reduction. The proposed system is considered not only the first demonstrator of a receive-only spaceborne DBF system, but also the first X/Ka-band dual-polarized SAR system with shared aperture. This paper presents a description of the proposed instrument hardware and first experimental validations. The concept and design of the DBF multistatic SAR system are discussed and presented first, followed by the design of subsystems such as DBF networks, microwave integrated circuit, and antennas. Simulated and measured results of the subsystems are presented, demonstrating that the proposed SAR instrument architecture is well-suited for the future SAR applications.

Gain-Enhanced Ka-Band MIMO Antennas Based on the SIW Corrugated Technique

Abstract: A novel single-layer substrate integrated waveguide (SIW) corrugated technique, consisting of an SIW slot and two SIW grooves, is proposed in this letter, based on which two high-gain and low-mutual-coupling Ka -band multiple-input–multiple-output (MIMO) antennas are demonstrated. The mechanism of gain enhancement of basic element is elaborated first before the analyses of the MIMO antennas. The simulated and measured results show that the elements of MIMO 1 and 2 antennas have an average 1.6 GHz (5.8%) bandwidth from around 26.8 to 28.4 GHz, and the gains can be up to 9.5 and 11 dB, respectively, with approximately 3 and 4.5 dB gain enhancement compared to those without SIW grooves. More than 20 dB high isolations between the elements can be achieved for both MIMO antennas. Subsequently, the study of envelope correlation coefficients exhibits their good MIMO performance.

3D-printed Ka-band waveguide array antenna for mobile SATCOM applications

Abstract: Purely passive, mechanically steered waveguide-fed horn arrays are good candidates to satisfy the current need for low-to-medium-profile antennas for mobile user terminals for SATCOM applications In this work, a unique waveguide feed architecture is proposed, which enables the realization of grating lobe-free, wideband, low-profile waveguide-fed horn arrays operating with dual circular polarization The realization of such structures using 3D printing is investigated, showing the promise of such techniques in terms of design flexibility To demonstrate the potential of the proposed waveguide array architecture combined with 3D printing, an 8-by-8 antenna array operating in the 20 GHz SATCOM Ka band has been developed and is presented This antenna exhibits an aperture efficiency of about 80% over a relative bandwidth larger than 10%

Retrieval of Sun Brightness Temperature and Precipitating Cloud Extinction Using Ground-Based Sun-Tracking Microwave Radiometry

Abstract: Sun-tracking (ST) microwave radiometry is a technique where the Sun is used as a microwave signal source and it is here rigorously summarized. The antenna noise temperature of a ground-based microwave radiometer is measured by alternately pointing toward-the-Sun and off-the-Sun while tracking it along its diurnal ecliptic. During clear sky the brightness temperature of the Sun disk emission at K and Ka band and in the unexplored millimeter-wave frequency region at V and W band can be estimated by adopting different techniques. Using a unique dataset collected during 2015 through a ST multifrequency radiometer, the Sun brightness temperature shows a decreasing behavior with frequency with values from about 9000 K at K band down to about 6600 K at W band. In the presence of precipitating clouds the ST technique can also provide an accurate estimate of the atmospheric extinction up to about 32 dB at W band with the current radiometric system. Parametric prediction models for retrieving all-weather atmospheric extinction from ground-based microwave radiometers are then tested and their accuracy evaluated.

Ka-band RF MEMS capacitive switch with low loss, high isolation, long-term reliability and high power handling based on GaAs MMIC technology

Abstract: This study presents a Ka-band radio frequency (RF) micro electro mechanical systems (MEMS) capacitive switch with low loss, high isolation, long-term reliability and high power handling based on GaAs microwave monolithic integrated circuit (MMIC) technology. In this design, a T-matching structure is employed to realise impendence matching at ‘up-state’ by modifying the dimensions of centre signal line. Thus, the reflection loss and insertion loss are improved effectively. Measurement results show that in ‘up-state’ position, the input reflection coefficient (S 11) is less than −20.4 dB with the forward transmission coefficient (S 21) of better than −0.27 dB at Ka-band (27–40 GHz). At ‘down-state’, the switch is designed in a state of self-resonance to obtain high isolation. The measured isolation is better than 20 dB over Ka-band and can reach 35 dB at its self-resonant frequency of 35 GHz. The measured actuation voltage is about 36 V. The measured lifetime is at least 5.76 × 107 cycles. The measured power handling capability can reach up to 39 dBm. The proposed compact RF MEMS capacitive switch possesses excellent performances in terms of low insertion loss, high isolation, long lifetime and high power handling capability.

Sharp roll-off planar lowpass filter with ultra-wide stopband up to 40 GHz

Abstract: A microstrip planar lowpass filter (LPF) with sharp roll-off and ultra-wide stopband up to 40 GHz is presented. The central part of the LPF consists of three basic circular sectors, two smaller quadrants and a number of high-impedance lines that are cross-coupled to form a high cut-off rate and a moderate stop band from 2.3 to 10 GHz. Then, four types of resonator cells, three of which are high-impedance lines loaded with semi-circulars and one of which comprises folded step-impedance lines, are added to the central part to generate additional transmission zeroes up into Ka band. As a result, an ultra-wide stopband with 18th-harmonic suppression has been attained. A demonstration filter with 3 dB cut-off frequency of 1.96 GHz has been designed and fabricated. The measured results show that the relative stopband bandwidth of the LPF is 180% with suppression level >25 dB, and the roll-off rate is 104 dB/GHz. The functional area size of the LPF is 18.4 × 11.6 mm, which corresponds to 0.189 × 0.121λ g (λ g is the guided wavelength at f c).

Design and Performance of a Wideband Ka-Band 5-b MMIC Phase Shifter

Abstract: In this letter, the design and performance of a Ka-band 5-b monolithic microwave integrated circuit phase shifter is presented. In the 180° phase bit, a developed switched-path-type topology is employed in order to extend the bandwidth and achieve good phase shifting characteristics. The fabricated phase shifter demonstrates an rms phase error of less than 4.7° and an rms amplitude error of less than 0.6 dB over the frequency band from 31 to 40 GHz. The input and output return loss is measured to be better than 9 dB, and the chip size is 2.55 mm $\times1.3$ mm.

Ka-band user antennas for VHTS GEO applications

Abstract: Very High Throughput Satellite (VHTS) user antennas with their large number of beams and very large beam scans present several new design challenges One of these challenges is to control scan aberrations as they lead to high scan losses, low C/I and ultimately, lower capacity This paper presents a comparison between the results of various array-fed reflector antenna designs that are considered for VHTS missions

Ultra-wideband phased array for small satellite communications

Abstract: There is a continuing need for reducing size and weight of satellite systems, particularly in light of recent efforts to increase the functional role of small- and nano-satellites (for instance SmallSats and CubeSats). To this end, a family of arrays is presented, demonstrating ultra-wideband operation across the numerous satellite communications frequencies up to the Ku-, Ka-, and millimetre-wave bands. The first design is demonstrated to operate from 3.5–18.5 GHz with VSWR < 2 at broadside, and validated through fabrication of an 8 × 8 prototype. Additional designs operating from 7–37 and 9–49 GHz, both with VSWR < 2.1 at broadside, are verified via simulations only. These designs are optimised for low cost, using printed circuit board fabrication and appropriate materials selection for space application. E- and H-plane scanning patterns are provided. Finally, multi-physics simulations of the array in high-power transmit are conducted. Temperature trends and distribution are given, with the array showing favourable distribution of thermal energy at up to 2 W of RF input power per element, and a peak temperature only 40°C above ambient.

Wideband circularly-polarized 3-bit transmitarray antenna in Ka-band

Abstract: This paper describes the design of a 3-bit circularly-polarized transmitarray antenna operating in Ka-band The array is based on a unit-cell composed of two U-shaped slot loaded patch antennas, which are connected by a metallized via hole and printed on two identical dielectric substrates The latter are separated by a ground plane and bonded by a CuClad 6700 film A 400-element transmitarray is simulated and demonstrates a maximum gain of 275 dBi, an aperture efficiency of 478% at 29 GHz The 1-dB gain-bandwidth (LHCP) is equal to 148% at 29 GHz The 1-dB axial ratio bandwidth covers the frequency band between 27–32 GHz A good agreement is obtained between the full-wave simulation results performed with Ansys HFSS and the ones obtained using our hybrid in-house simulation tool The impact of phase quantization on the performance of a 40×40-element array is also presented The corresponding radiation patterns (co- and cross-polarization components) are compared to the masks defined by the European International Standardization Institutions (ETSI) in the case of point-to-point applications

RainCube, a Ka-band Precipitation Radar in a 6U CubeSat

Abstract: RainCube (Radar in a CubeSat) is a technology demonstration mission to enable Ka-band precipitation radar technologies on a low-cost, quick-turnaround platform. As of the publication date, the 6U CubeSat is in the assembly, integration, and test phase leading towards an expected delivery to storage in September 2017. The mission is manifested for an ISS deployment on the ELaNa-23 launch, currently scheduled in the first half of 2018. Radar instruments have often been regarded as unsuitable for small satellite platforms due to their traditionally large size, weight, and power. The Jet Propulsion Laboratory has developed a novel radar architecture compatible with the 6U form factor. The RainCube mission will validate two key technologies in the space environment – a miniaturized Ka-band precipitation profiling radar that occupies ~3U and a 0.5m Ka-band deployable parabolic antenna stowed within 1.5U. The spacecraft bus is developed by Tyvak Nanosatellite Systems, who is responsible for integration and test of the flight system and mission operations. RainCube is funded through the NASA Science Mission Directorate’s Research Opportunities in Space and Earth Science 2015 In-Space Validation of Earth Science Technologies solicitation with the goal of raising the instrument TRL to 7.

A Ka-band 4-ch bi-directional CMOS T/R chipset for 5G beamforming system

Abstract: This paper presents a Ka-band 4-channel bi-directional T/R chipset in 65 nm CMOS technology for 5G beamforming system. The proposed T/R chipset can provide bi-directional operation with moderate gain and dual polarization. Each channel consists of bi-directional gain blocks, a 5-bit step attenuator and a 5-bit phase shifter including tuning bits. The phase and attenuation coverage are 348° with the LSB of 11.25° and 31 dB with the LSB of 1 dB, respectively. The gain of 13 dB (Tx mode) and 6 dB (Rx mode) are achieved at 28 GHz including the 4-way power divider/combiner.

Design of a 2-bit unit-cell for electronically reconfigurable transmitarrays at Ka-band

Abstract: This paper presents in detail the design of a linearly-polarized electronically reconfigurable unit-cell for transmitarray antennas with a 2-bit phase resolution in Ka-band. The size of the proposed unit-cell is 5.1∗5.1×1.3 mm3. It is implemented on a dielectric stack-up composed of six metal layers, three dielectric substrates and two bonding films. The radiating elements are printed on both external metallic layers and are loaded by two PIN diodes controlling the transmission phase. This unit-cell is used to design a 196-element transmitarray with 784 PIN diodes. The performance of this 2-bit transmitarray has been evaluated numerically using our in-house simulation tool and compared to a transmitarray with a 1-bit phase quantization. A maximum gain of 22.9 dBi, an aperture efficiency of 32.3%, and a side-lobe level equal to −18.1 dB at broadside have been obtained at 29 GHz.

Compact Dual Band Antenna Design for Ku / Ka Band Applications

Abstract: This communication proposes a compact 16 GHz / 30 GHz dual band antenna design for Ku / Ka band applications. The antenna consists of two layers with lower layer having the fed patch and the upper layer having non-periodic element array. The antenna has been designed to operate at two different frequencies with compact dimensions of (8mm x 8mm) using Rogers RT 5880. The compact size of this proposed antenna also makes it suitable for integration with the microwave and millimeter wave circuits. The proposed antenna provides high radiation efficiency and a peak gain of about 8 dB at the resonant frequencies with reduced side lobe levels.

Investigation of a Ka-Band High-Power Sheet Beam Relativistic Extended Interaction Oscillator

Abstract: The sheet beam relativistic extended interaction oscillator (REIO) is a very important high-power millimeter-wave source for many actual and potential applications. A Ka-band sheet beam REIO is designed by means of particle-in-cell (PIC) simulation. In the design, we adopt a sheet electron beam with dimensions of 45 mm $\times1.5$ mm to reduce the space charge effect and the extended interaction cavities to increase the power capacity. The results of the PIC simulation demonstrate the device can generate an output power of 404 MW at 30 GHz with an efficiency of 20%. In addition, we develop the experiment on a short-pulse accelerator. In the experiment, the oscillator generates a millimeter-wave power of 125 MW with a beam current of 4 kA, a beam voltage of 500 kV, and guiding magnetic field of 1 T. The frequency of the output millimeter wave is 30.6 GHz and the pulsewidth is 16 ns. The experiment proves that millimeter wave of over 100 MW can be generated with the sheet beam REIO.

Design of Carbon Nanotube-Based Broadband Radar Absorber for Ka-Band Frequency Range

Abstract: The general principles of design and development of microwave absorbing materials are discussed and analysed in respect to 26–37 GHz frequency range (Ka-band). Dispersive composite materials based on carbon nanotubes in epoxy resin matrix are produced, and their electromagnetic responses are investigated in Ka-band. Both theoretical and experimental results demonstrate that presented composites may be used as compact effective absorbers in 26–37 GHz range.