Mm-wave high gain cavity-backed aperture-coupled patch antenna array

© 2013 IEEE. A wideband and high gain cavity-backed 4 × 4 patch antenna array is proposed in this paper. Each patch antenna element of the array is enclosed by a rectangular cavity and differentially-fed by the slot underneath. By optimizing the geometry of the radiating patch and the cavity, a very uniform E-field distribution at the antenna aperture is achieved, leading to the high array aperture efficiency and thus the gain. Taking advantages of the higher-order substrate integrated cavity excitation, the elements of the array are efficiently fed with the same amplitude and phase in a simplified feeding mechanism instead of the conventional bulky and lossy power-splitter-based feeding network. Measured results show the antenna bandwidth is from 56 to 63.1-GHz (16.1%) with the peak gain reaching 21.4 dBi. The radiation patterns of the array are very stable over the entire frequency band and the cross-polarizations are as low as -30 dB. These good characteristics demonstrate that the proposed array can be a good candidate for the future 60-GHz communication system applications

Highly Efficient Unpackaged 60 GHz Planar Antenna Array

A high gain antenna array is designed and fabricated at 60 GHz. The array is via-less and made on a single dielectric substrate. It can be easily integrated with millimeter wave transceivers. Very good agreement between the measured and simulated results is achieved. The array has 22.5 dBi gain with a maximum efficiency of 93% and a 3.2 % bandwidth

Low Cost High Gain Millimeter Wave Planar Antennas

The advent of the fifth generation of wireless communication systems mandates the use of high gain antennas for transceiver front ends. The use of high gain antennas is very vital in order to compensate for the high path loss of the propagating signals at millimeter wave frequencies. There are many methods to implement high gain antennas; many of those solutions are expensive and complicated in terms of its fabrication process. Here, we emphasize 60 GHz high-gain antennas based on the low cost planar printed circuit board technology. The proposed solutions are low cost with high performance metrics. The proposed antennas suit short range, low power applications, such as wireless personal area networks (WPAN). Nonetheless, the study provided for the proposed structures reveals new physical insights, and new methods for the design procedure, where the design procedure becomes very straightforward. The first proposed structure utilizes the radiation losses in microstrip line discontinuities to implement an efficient high gain radiator at 60 GHz. The second proposed structure utilizes the diffracted fields from the edges of metal sheets as secondary radiating sources to boost the gain of the element. Also, an increased distance between the antenna elements can be achieved without generating grating lobes; this can be comprehended by visualizing each element as a subarray of radiating sources. Such a concept has a significant implication on the relaxation of the design of feeding networks. The single antenna element realized gain goes up to 11.5 dBi, the 10 dB return loss bandwidth covers the 60 GHz ISM band, and the radiation efficiency goes above 90%. A Magneto-Electric (ME) dipole is usually designed by superimposing electric and magnetic current elements orthogonally on each other. A new design procedure is proposed, which can transform the radiation characteristics of an electric or magnetic current element to a Magneto-Electric dipole characteristics. The proposed procedure doesn’t require the orthogonal combination of the magnetic and electric current elements. Hence, the procedure possesses a significant advantage, where it avoids the need for a quarter free-space wavelength spacing between the current element and the metallic ground plane. In addition, the proposed design increases the antenna gain dramatically, where the proposed structure has a boresight gain of 11.5 dBi, and a relative bandwidth of 13% centered at 60 GHz. The antenna element has been employed in a planar antenna array to achieve a gain of 22 dBi. A novel technique is proposed to enhance the gain of a Dielectric Resonator Antenna (DRA) over a wideband range of frequencies. The proposed antenna structure has a relative bandwidth of 27.5% in the 60 GHz band, and a peak realized gain of 12.5 dBi. The peak of the total antenna radiation efficiency is 96%. The proposed antenna is suitable for high data rate short range personal area networks applications. Printed Electromagnetic Band Gap (EBG) technology is used to feed the antenna to eliminate any parasitic radiation from the feed line. The characterization of 60 GHz antennas is very challenging. The end launch connector used to feed the antenna at such frequency is relatively large compared to the antenna dimensions, and that consequently affects the accuracy of the characterization of the antenna, especially if it is in the vicinity of the antenna. EBG surfaces have been used to resolve such characterization impairments. In a 5G network, the data is communicated at mm-wave frequencies between various communicating entities. The communicated high frequency signal is processed internally within the communicating entity itself. Thus, the data is communicated through electrical interconnects between several chips or between several sub-circuits within the chip. In such a way, those electrical interconnects between various sub-circuits within an Integrated Circuit (IC), or between several adjacent ICs, play a vital role in defining the performance limits of any system. As the frequency of operation gradually increases, the design of interconnects, whether within the IC environment (intra-chip) or between several adjacent ICs (inter-chip), turn into a more challenging task. As the frequencies of operation increase, the proper interconnect guiding structure dimensions become infeasible to realize, or it might exhibit a high level of losses, and large intrinsic RC time delay. Moreover, by the increase of the number of interconnects, the mutual coupling between the interconnect structures become more severe, not to mention the complexity, and associated cost of such design. The wireless interconnects concept (wireless intra-chip/inter-chip communication) emerged as a suggested remedy to the high frequency interconnect problem. We provide a study of several aspects of wireless inter-chip communication between adjacent ICs at mm-wave frequencies. The symmetrical layers concept is introduced as a general approach to eliminate the destructive interference and redirect the wasted radiated energy to free space towards the receiving antenna. In addition, the use of hard/soft surfaces and EBG structures to focus the radiated energy towards the receiving antenna is studied thoroughly. The use of such concepts has tremendous advantages, in focusing the energy towards the receiving antenna and eliminating the spherical spreading losses introduced by the radiated spherical wave nature. The incorporation of the symmetrical layers with hard/soft surfaces led to novel compact, low-cost wireless inter-chip structures with enhanced link budget performance

High Gain Broadband mm-Wave Antenna Arrays for Short-range Wireless Communication Systems

Recently, the ever-increasing demand for fifth-generation (5G) wireless applications has turned millimeter-wave (mm-wave) multi-beam array antenna into quite a promising research direction. Besides offering a remarkable bandwidth for high-speed wireless connectivity, the short wavelengths (1 to 10 mm) of mm-wave signals makes the size of the antenna array with beamforming network (BFN) compatible with a transceiver front-end. The high losses associated with mm-wave wireless links and systems considered the foremost challenge and may restrict the wireless communication range. Therefore, a wideband substrate integrated waveguide (SIW)-based antenna with high gain and beam scanning capabilities would be a solution for these challenges, as it can increase the coverage area of mm-wave wireless systems and mitigate the multipath interference to achieve a high signal to noise (S/N) ratio, and thereby fulfill the link budget requirements. This thesis focuses on the analysis and design of single- and multi-beam mm-wave antenna arrays based on SIW technology to fulfill the growing demand for wideband high-gain planar antenna arrays with beam steering capability at V-band. A tapered slot antenna (TSA) and cavity-backed patch antenna are used as the main radiators in these systems to achieve high-gain and high efficiency over a wide range of operating frequencies. Accordingly, numerous design challenges and BFN-related issues have been addressed in this work. Firstly, an antipodal Fermi tapered slot antenna (AFTSA) with sine-shaped corrugations is proposed at V-band. The antenna provides a flat measured gain of 20 dB with a return loss better than 22 dB. In addition, A broadband double-layer SIW-to-slotline transition is proposed to feed a planar linearly tapered slot antenna (PLTSA) covering the band 46-72 GHz. This new feeding technique, which addresses the bandwidth limits of regular microstrip-to-slotline transitions and avoids the bond wires and air bridges, is utilized to feed a 1x4 SIW-based PLTSA array. Secondly, a new cavity-backed aperture-coupled patch antenna with overlapped 1-dB gain and impedance bandwidth of 43.4 % (56-87 GHz) for |S11| < -10 dB and an average gain of 8.2 dBi is designed. A detailed operating principle is presented. Based on the proposed element, an SIW based 1x8 array is constructed, whose beam-shape is synthesized by amplitude tapering according to Taylor distribution to reduce the sidelobe level. Moreover, a four-layered 4x4 cavity-backed antenna array with a low-loss full-corporate SIW feed network is implemented for gain and aperture efficiency enhancement. The measured results exhibited a bandwidth of 38.4 % (55.2-81.4 GHz) for |S11| < -10 dB and a gain of 20.5 dBi. A single-layer right-angle transition between SIW and air-filled WR15 waveguide along with an equivalent circuit model is introduced and used to measure the performance of both proposed linear and planar arrays. Thirdly, two 1-D scanning multi-beam array designs based on SIW technology, at 60 GHz, have been presented. The first design is a compact multi-beam scanning 4x4 slot antenna array with broadside radiation. The BFN is implemented using a dual-layer 4x4 Butler matrix, where the 450 and 00 phase shifters are designed on a separate layer with different permittivity, resulting in a significant size reduction compared to a conventional single layer. A detailed theoretical analysis, principle of operation and the circuit-model of the proposed phase shifter have been discussed, showing less desperation characteristics compared to ordinary phase shifters. The measured results show an azimuthal coverage of 1210. The second design is a wideband high gain multi-beam tapered slot antenna array with end-fire radiation. An SIW Butler matrix with a modified hybrid crossover is used as a BFN. The fabricated prototype exhibits a field of view of 970 in the azimuthal plane, with measured gain ranges from 12.7 to 15.6 dBi. Lastly, a novel three-layered SIW-fed cavity-backed linearly polarized (LP) patch antenna element is presented, covering a bandwidth of 36.2 % (53-76.4 GHz) with a flat gain ranging from 7.6 to 8.2 dBi. A compact two-layered beam forming network is designed with a size reduction of 28 % compared to a standard one-layered BFN without affecting its s-parameters. The results show that the impedance bandwidth is 31.1 % (51.5-70.5 GHz) for |S11|<-16 dB with an average insertion loss of 1.3 dB. The proposed antenna element and BFN are employed to form a compact 2x2 multibeam array at 60 GHz for 2-D scanning applications. The array shows a bandwidth better than 27 % with a radiation gain of up to 12.4 dBi and radiation efficiency of 80%. The multi-beam array features four tilted beams at 330 from a boresight direction with 450, 1350, 2250 and 3150 in azimuth directions, i.e., on e beam in each quadrant