Millimeter-wave Wireless Applications Research Articles

Wideband Dipole Array Loaded Substrate Integrated H-Plane Horn Antenna for Millimeter Waves

A novel dipole array loaded substrate integrated H-plane sectoral horn antenna with a simple three-layered geometry is proposed. The dipole array integrated into two extra dielectric strips is connected to the top and bottom edges of the horn aperture. Both the horn aperture and the dipole array are effectively radiated together. A wide impedance bandwidth of 44% for $\vert S_{11}\vert dB that can cover the entire Ka-band is verified by a fabricated prototype. Additionally, stable symmetrical radiation pattern with low cross polarizations, low backward radiation, and gain up to 12 dBi with a variation of 3 dB can also be obtained throughout the whole operating band. The proposed antenna provides a new mean to design wideband substrate integrated horns with excellent endfire radiation, which would be attractive for future wideband and multiband millimeter-wave wireless applications, including the fifth generation (5G) mobile communications and the WiGig system.

A Multibeam End-Fire Magnetoelectric Dipole Antenna Array for Millimeter-Wave Applications

A novel substrate integrated waveguide (SIW)-fed end-fire magnetoelectric (ME) dipole antenna is proposed. The antenna consisting of an open-ended SIW and a pair of electric dipoles has a simple structure that can be integrated into substrates conveniently. Both the open-ended SIW and the electric dipoles are effectively radiated together. Excellent performance, including a bandwidth of 44%, symmetrical radiation patterns that are almost identical in two orthogonal planes, low backward radiation, low cross polarizations, stable gain of around 5 dBi, and wide beamwidth of around 110°, are also obtained. An $8 \times 8$ SIW Butler matrix is then designed. Modifications to the geometry of the matrix provide more spacing to locate SIW phase shifters and phase compensation structures with wide bandwidth. By employing the proposed end-fire ME-dipole antenna array and the $8 \times 8$ Butler matrix, an eight-beam antenna array is realized. The fabricated prototype demonstrates that wide bandwidth, stable radiation patterns with cross polarizations of less than −28 dB and gain varying from 9 to 12 dBi can be obtained. The proposed multibeam end-fire ME-dipole antenna array would be an attractive candidate for millimeter-wave wireless applications due to its good performance, ease of integration, and low fabrication cost.

Cavity-Backed Angled-Dipole Antennas for Millimeter-Wave Wireless Applications

A cavity-backed angled-dipole antenna is proposed for millimeter-wave wireless applications. The angled-dipole radiator is built on both sides of an RT/Duroid 5880 substrate (εr=2.2) and fed by a parallel-plate transmission line. The cavity-backed reflector is utilized to improve the radiation characteristics of the angled dipole, such as gain, back-radiation, symmetric pattern, and similar 3 dB beamwidth in theE- andH-planes. The design, with a cavity aperture of0.5λ28-GHz×0.5λ28-GHz, results in aS11<-10 dB bandwidth of 26.7–30.6 GHz, a gain of 6.6–8.0 dB, and a similar 3 dB beamwidth of approximately 70° for both theE- andH-planes. Eight-element linear arrays with the proposed antenna having a center-to-center spacing of 5.6 mm(0.52λ28-GHz)are characterized, fabricated, and measured. By applying nonuniform power distribution across excitations, the array achieves a scan angle up to 40° and a sidelobe level below −15 dB.

Millimeter-Wave Broadband Transition of Substrate Integrated Waveguide on High-to-Low Dielectric Constant Substrates

For emerging millimeter-wave wireless applications at W- and E-bands, active components including LNA and power amplifier are preferably fabricated or surface-mounted on the materials of a high dielectric constant (such as CMOS and MHMIC). On the other hand, antennas or radiating elements should be developed on relatively low-dielectric constant substrates for the enhancement of gain and bandwidth. Therefore, the development of a wideband transition from high-to-low dielectric constant substrates becomes necessary because the use of wire bonding schemes brings up packaging, interconnects, and manufacturing problems at millimeter-wave frequencies. This paper presents a novel integrated wideband transition of substrate integrated waveguide (SIW) on high-to-low dielectric constant substrates. The transition is made of a single-layer structure, which consists of a tapered high-dielectric constant substrate that connects two SIWs. Because of the waveguide-based structure of the transition, it has a self-shielded configuration, and its interference is minimum. Simulated and measured results show that the bandwidth of the proposed transition covers almost the entire W- and E-bands with low insertion loss.

Optimized Microstrip Antenna Arrays for Emerging Millimeter-Wave Wireless Applications

Two compact planar antennas operating in the unlicensed 60 GHz frequency band are presented based on the physical layer specifications of IEEE 802.15.3c and ECMA 387 standards for different classes of wireless applications. Each antenna is an array of 2 × 2 microstrip antennas covering at least two channels of the 60 GHz spectrum. The first antenna is optimized to achieve the highest gain, while the second antenna is optimized to give the largest beamwidth. The maximum measured radiation gain of the first antenna is 13.2 dBi. The measured beamwidth and gain of the second antenna are 76 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> and 10.3 dBi, respectively. The areas of these two antenna are only 0.25 and 0.16 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The variation of radiation gain of each antenna over the frequency range of 57-65 GHz is less than 1 dB.

Key technologies and system design for various radio over fiber applications

Key technologies and new system designs for various radio over fiber (RoF) applications are proposed and demonstrated. For ultrawideband (UWB) over fiber applications, several UWB pulses generation and distribution methods are carried out. Different kinds of UWB pulses are generated based on cross-polarization modulation methods. For millimeter-wave (mm-wave) wireless applications, a 32 GHz RoF system is demonstrated with microwave frequency sextupling by optical methods. After 20 km SMF transmission, the power penalty of 2.5 Gbit/s downlink service is less than 0.15 dB. It is also suitable to apply dense wavelength division multiplexing (DWDM) technology to RoF system to support numerous base stations (BSs).

Direct Conversion EHM Transceivers Design for Millimeter-Wave Wireless Applications

A direct conversion modulator-demodulator with even harmonic mixers for fixed wireless applications is presented. The circuits consist of even harmonic mixers (EHMs) realized with antiparallel diode pairs (APDPs). A communication link is set up to examine the overall performance of proposed modulator-demodulator. The transmission of 16-QAM signal with 110 Mbps data rate over fixed wireless link has been examined. We also evaluate the different levels of I/Q imbalances and DC offsets and use signal space concepts to analyze the bit error rate (BER) of the proposed transceiver using M-ary QAM schemes. The results show that this structure can be efficiently used for fixed wireless applications in Ka band.

Broadband printed sectorized coverage antennas for millimeter-wave wireless applications

We present a simple method to reduce the back radiation of broadband millimeter-wave printed antenna arrays. By utilizing specially designed reflector patches, the front-to-back ratio of an array of aperture stacked patches can be improved to greater than 30 dB across the entire 26-40 GHz frequency band, making this form of antenna array suitable for sectorized coverage local-multipoint-distribution service (LMDS) and picocellular mobile networks.

A mode-locked microchip laser optical transmitter for fiber radio

This paper is concerned with the optical domain generation of high-quality millimeter-wave signals for fiber-radio and other applications. The mode-locked millimeter-wave optical transmitter described is based on simple electrooptic microchip laser technology. The transmitter can be designed to operate from a few gigahertz to 100 GHz and beyond. The residual phase noise of the laser is below -100 dBc/Hz at 1-kHz offset, which makes it well suited for optically fed millimeter-wave wireless applications. A key feature of the transmitter is its simplicity, the very small number of elements it employs and the high level of integration of the millimeter-wave and photonic components that results in a small, rugged, and reliable package. The paper describes the design, fabrication, and experimental evaluation of the transmitter.