UWB Miniature Antenna Limitations and Design Issues

In this paper, a wide-band miniaturized Conformal conical Archimedean spiral (CCARS) antenna is proposed for Ultra wideband (UWB) communications. The CCARS antenna utilizes the vertical space instead of horizontal space significantly saving the antenna installation space. We investigate the transformation from Planar Archimedean spiral (PARS) antenna to the CCARS antenna and the antenna miniaturization technique. Due to the using of flexible dielectric substrate, the PARS antenna can be bent freely, which assures the transformation from the PARS antenna to the CCARS antenna. To realize antenna miniaturization, zigzag shape arms are applied to the PARS antenna. Moreover, the CCARS antenna has good unidirectional radiation property that avoids the using of traditional absorber-loaded back cavity. The measured results of antenna prototype indicate that the Voltage standing wave ratio (VSWR) is below 2 over the frequency range from 1.3GHz to 9GHz. The antenna gain is higher than 3.4dBi and the Front to back (F/B) ratio is better than 20dB from 2GHz to 7GHz. In addition, good radiation patterns and broad 3dB beam width are also available for the CCARS antenna.

A dual-band, 4×2 microstrip patch antenna (MPA) array for future 5G communication applications is proposed in this paper. The single element antenna of the proposed array configuration is a dual band patch antenna with dimension of 8×8 mm². This proposed single element antenna has resonance frequencies of 29 GHz and 40.5 GHz, and achieves 5.69 dBi and 4.54 dBi gain at the center frequencies respectively. The attained -10dB impedance bandwidth of the single element antenna is 10.34% and 12.34% at two operating frequency bands. Using corporate fed and series fed, the proposed 8-element MPA array is designed from this single element. The dimension of the proposed array antenna is 38 × 15 mm2 and low-cost FR-4 material is used as the substrate. The proposed array antenna resonates at 29.5 GHz and 38 GHz, and provides 8.4 dBi and 9.3 dBi total gain at the resonance frequencies respectively. Thus, improved bandwidth and better radiation performance over required frequency bands, high gain and use of low-cost material makes the proposed antenna perfect for 5G communication/wireless communication applications.

The excessive use of digital platforms with rapidly increasing users in the wireless domain enforces communication systems to provide information with high data rates, high reliability and strong transmission connection quality. Wireless systems with single antenna elements are not able to accomplish the desired needs. Therefore, multiple-input multiple-output (MIMO) antennas are getting more attention in modern high-speed communication systems and play an essential part in the current generation of wireless technology. However, along with their ability to significantly increase channel capacity, it is a challenge to achieve an optimal isolation in a compact size for fifth-generation (5G) terminals. Portable devices, automobiles, handheld gadgets, smart phones, wireless sensors, radio frequency identification and other applications use MIMO antenna systems. In this review paper, the fundamentals of MIMO antennas, the performance parameters of MIMO antennas, and different design approaches and methodologies are discussed to realize the three most commonly used MIMO antennas, i.e., ultra-wideband (UWB), dual-band and circularly polarized antennas. The recent MIMO antenna design approaches with UWB, dual band and circularly polarized characteristics are compared in terms of their isolation techniques, gain, efficiency, envelope correlation coefficient (ECC) and channel capacity loss (CCL). This paper is very helpful to design suitable MIMO antennas applicable in UWB systems, satellite communication systems, GSM, Bluetooth, WiMAX, WLAN and many more. The issues with MIMO antenna systems in the indoor environment along with possible solutions to improve their performance are discussed. The paper also focuses on the applications of MIMO characteristics for future sixth-generation (6G) technology.

A combination of UWB technology with MIMO technology is applied for designing and simulating a 18×17.5×1.6mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> sized single element antenna and the two different configurations of 18×35×1.6mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> sized MIMO array that can be utilized for Ultra Wide Band applications. The single element antenna consists of a compact patch with two rectangular slots which is fed by a 50Ω coplanar waveguide line with a common ground. Having better resonance and a gain of 11dB it achieves a 3 to 10.3GHz wide band. By placing two such single elements on the same side and by making one of them perpendicular to the other, two MIMO antenna arrays are created. Both the arrays almost achieve a wide bandwidth from 3 to 10.3GHz with appreciable resonance and gain of 12.5 and 12.8dB respectively. The designing and simulation is done in ANSYS HFSS version 2021 and the parameters like return loss, radiation pattern, gain, current distribution, VSWR, impedance characteristics, ECC etc. are plotted for their performance comparison.

Graphene based array antennas are becoming more popular for wireless applications due to their ultra slim structure, versatile nature, flexibility, robustness and other advantages as compared to conventional patch antennas. Small size and high gain coplanar waveguide (CPW) feed single element microstrip patch antenna (MPA), 16 elements array antenna and 32 elements array antenna for millimeter wave applications are presented in this paper. The proposed antenna configurations have been designed and simulated using computer simulation technology (CST). Kapton is used as the dielectric substrate having dielectric constant of 3.5 and thickness of 0.075 mm. Graphene is used in the radiating patch as well as ground plane of the antennas whose electrical conductivity is of 1.4286 × 106 S/m2. The thickness of patch and ground plane are of 0.025 mm and 0.05 mm respectively. Each single element antenna has dimension of 1.75×1.5×0.075 mm3 and each array configuration consist of corresponding number of same dimensional single elements. The results of all the proposed antenna configurations have been analyzed in terms of return loss, bandwidth, gain, VSWR and radiation efficiency. Among all the proposed antennas and analyzed feeding methods, the grounded coplanar waveguide (GCPW) feed 32 elements array antenna shows the best performance.

Ultra-wide-band (UWB) wireless systems are often applied to short-range high-speed data transmission. According to Shannon formula, UWB system with gigahertz band can reach ultra-high data transmission rate. The Shannon capacity of a communication channel is the maximum transmission rate that the channel can support, and it increases with higher signal to noise power ratio (SNR) and wider bandwidth. However, as widening bandwidths often lead to higher noise power, it is SNR rather than the bandwidth that plays the key role in setting the actual data transmission capacity of a channel. With a significant potential of enhancing SNR, multi-band orthogonal frequency-division multiplexing ultra-wide-band (MB-OFDM UWB) system is able to achieve much higher anti-noise capability and flexibility than the conventional impulse radio (IR) UWB. MB-OFDM UWB with multiple-input multiple-output (MIMO) antennas is a viable way to improve channel capacity and expand coverage area. Simulations show that larger quantity of receiver antenna can improve channel capacity even when the total number of transmitter and receiver antenna is constant. A channel estimation algorithm in MIMO-OFDM technology also can be applied to UWB communications. Simulation shows MB-OFDM UWB systems with MIMO technology can achieve better bit error rate performance than the MB-OFDM UWB systems with single transmitter and receiver antenna.

Summary form only given. Since its inception, the durable, conformal, and low profile equiangular spiral antenna has enticed private enterprise and public entities to expand and enhance applications for biotechnology, communications, military, and space implementation. The spiral antenna's ultra-wideband (UWB), high efficiency, and circular polarized features attract implementation where physical and electromagnetic environment conditions fluctuate such as intelligence gathering, astronaut extra vehicular activities, satellite communications, navigation, and disaster communications. Impedance matching the spiral is critical. Common solutions utilize a balun or an impedance transformer. These solutions preserve the antenna's efficiency and radiation profile. Some examples of balun and impedance transformers applied to spiral antennas include integrating planar microstrip baluns with vias, complex coplanar strip designs, multi-layer substrates with strip lines, coaxial cables, perpendicular feed lines, etc. Balun designs have a limited impedance bandwidth or add manufacturing complexity impeding spiral antenna implementations. NASA has developed a conformal S-band equiangular spiral antenna constructed from commercially available e-textiles made from polyester cloth plated by a mixture of silver, copper, and nickel. The e-textile fabrication made the antenna malleable to clothing, spacesuits, flags, etc.; however, the inflexible coaxial cable balun leaves the structure vulnerable to damage. Unforgiving environments, such as outer space, necessitate design and fabrication considerations for resiliency and robustness.

This paper covers five different types of single element beam scanning antennas under electronic switch control. Firstly, a rectangular spiral antenna with shorting and open switches is presented. Following that, its polarization and other antenna parameter limitations are addressed. Then new structures, namely: star strip, star patch and square loop antennas, introduced to overcome the polarization problem in the spiral antenna, are covered. All these new antennas are symmetrical, and have 4 feeding points. When excited individually, these feeding points generate four tilted beams of the same characteristics in different quadrants, yielding a complete beam scanning antenna. The gains for these three antennas for each of the feed configurations are approximately 8.1 dBi and the polarization dominance is in the E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">thetas</sub> direction. Finally future work on implementing switches including MEMS on the ground plane of the antennas for switching the beam of the antennas is outlined.

The fifth generation (5G) mobile communications systems demand millimeter wave (mmWave) bands of the electromagnetic spectrum beside the current sub-6 GHz frequencies. Allocation of mmWave frequencies for the cellular systems will ensure more capacity and higher speed links. For the last few years wireless communications societies in industry and academia have put significant research effort to develop novel and efficient antenna architectures. We need brand-new antenna structures that can overcome the challenges of 5G communications environment such as high propagation loss of mmWaves and the large bandwidth demand of the planned networks. In this paper, a microstrip mmWave antenna array for 5G mobile phone terminals is introduced. First, the single antenna element with the rectangular patch radiator is investigated. The numerical investigation is carried out with a full-wave electromagnetic solver. The single antenna design operates between 27.1 GHz – 28.95 GHz frequencies. The proposed antenna based on microstrip approach shows low profile characteristics without compromising performance. A maximum gain of ~7.7 dBi is achieved within the operation band. Then eight-element phased array implementation of the proposed antenna is analyzed. Uniformly spaced linear array method is used with ~λ/2 spacing in the configuration. The eight-element array boosts the maximum total gain value up to ~ 15 dBi, and yields beam steering at broadside up to ∓50° with low side lob levels (SLL). Furthermore, the proposed phased array design is compact with the dimensions of 10 mm×48.6 mm×0.51 mm, and therefore it is compatible with the mmWave band radio frequency integrated circuit (RFIC) transceivers.

The main objective this work is to design and simulate different shaped (S, E, C and Combined S-E-C) compact and planar micro-strip patch antenna (MPA) array for multiband wireless applications. The proposed antennas have been designed and simulated using advanced design system (ADS). Each single element antenna has dimension of 40×30 mm2 and each array consists of corresponding three or four same dimensional single elements. Micro-strip line feed technique and dielectric substrate named quartz having dielectric constant of 4.2, tangent loss of 0.0013 & height of 1.6 mm have been considered in the proposed antennas. The results have been analyzed in terms of return loss, bandwidth, directivity, gain & radiation efficiency and finally compared with literature review.

This paper proposes the design of a compact sub-6 GHz four-port flexible antenna for utilization in 5G applications. A two-arm monopole with a coplanar waveguide feed line printed on a flexible substrate was proposed to shape the single-element antenna. The single element was designed, fabricated, and measured first; then, four copies of the single element were organized on a single flexible substrate to compose the four-port antenna. The MIMO antenna was simulated, fabricated, and experimentally measured. All the simulations and measurements of the flexible single element and MIMO antennas are presented. The presented MIMO antenna showed good impedance characteristics, with a deep level of −24 dB from 3 to 4.12 GHz. The antenna had omnidirectional and bi-directional patterns in the φ = 0° and φ = 90° planes. As an important parameter evaluation for MIMO, the mutual coupling between the different ports was investigated. The diversity gain (DG), the total active reflection coefficient (TARC), the mean effective gain (MEG), the envelop correlation coefficient (ECC), and the channel capacity loss (CCL) parameters were investigated and showed good performance. All the obtained simulation results were in a high degree of agreement with the measurement results, supporting the usage of the suggested antenna in 5G communications.

This paper discusses the simulation & measurement analysis for Lightweight, Circularly Polarized, Ultra wideband Wide coverage single turn axial mode Monofilar helical antenna for space applications. Single Turn axial mode Monofilar helical Antenna shows ultra wideband characteristics having bandwidth of 35GHz i.e. 450% of the designed frequency for the antenna for VSWR < 2. The bandwidth span starts from 7.5GHz & end up to 42.5GHz. During this span single antenna covers X-Band, Ku-band, K-Band & Ka-band. Antenna has wide coverage i.e. 3dB beamwidth of 70° & has gain up to 8.2 dB for desired frequency. Axial ratio of 1.6 dB has been achieved for design frequency. Antenna is extremely lightweight as it involves just wound copper wire single turn & teflon as dielectric base plate with connector. Antenna meets EIRP requirement through the use of high power transmitter to meet link margin. Design & Simulation of Single Turn axial mode Monofilar Helical Antenna has been done on Ansoft HFSS v11.

The aim of this paper is describing a design, realization and measurement of ultra wide band (UWB) antenna by inkjet printing technology on polyimide substrate DuPont™ Kapton® HN 50.8 µm. For this purpose we used conductive silver based nano-ink AX JP-6n by Amepox Microelectronics LTD with particle size range between 3 – 7 nm in diameter. The realized antenna was designed and simulated in Ansoft HFSS™ 13.0. The frequency bandwidth of this UWB antenna is between 5.5 to 11.7 GHz that is according to decision of Federal Communications Commission. The impedance matching was realized by length of feeding element to 50 Ω. Paper includes the theoretical background of inkjet printing technology applied within UWB antenna realization.

Antenna integration and miniaturisation techniques are crucial for maintaining the desired electrical and physical properties of antennas, while meeting the growing demands for reliable link performance and compact device designs for emerging wireless communications. This Special Issue presents recent advances in the theory, analysis, design, and application of antenna integration and miniaturisation. These techniques are enabling diverse novel designs and applications, propelling advancements in integrated circuits, and next-generation wireless communication systems rapidly. The papers in this Special Issue present the state-of-the-art contributions that address the challenges of design, fabrication, and performance enhancement for miniaturised and integrated antennas. This Special Issue includes six high-quality papers, each presenting unique innovations in the field of antenna integration and miniaturisation. Thus, the overall submissions are of high quality, which marks the success of this Special Issue. Ye et al. present a high-gain circularly polarised magneto-electric dipole antenna array with metallic radiating structures for millimetre-wave applications. This paper proposes a novel design of a magneto-electric dipole antenna array for millimetre-wave applications. The novel use of metallic radiating structures helps achieve high gain and circular polarisation, making the proposed design ideal for millimetre-wave communication systems. Truong et al. introduce a method for designing an electrically small printed square loop antenna for closely spaced transmitter-receiver (Tx/Rx) systems. This paper demonstrates a compact antenna design, featuring a simple series combination of two lumped inductors and two interdigitated capacitors, providing inherent impedance matching without the need of an additional matching network. This proposed compact design method is highly relevant for modern and emerging wireless communication systems where space is often limited and confined. Mao et al. propose a null-depth coordinated synthesis design approach for azimuthal null frequency scanning antennas (ANFSAs). A synthesis chart gauged by different null-depths is developed to determine the respective exciting amplitude and phase conditions for the principal and auxiliary radiators. This method provides a promising solution for achieving efficient frequency scanning with an in-band null-depth as high as −30 dB. Choi et al. offer miniaturised ultra-wideband circular polarised Koch fractal crossed dipole array. The design incorporates a Koch fractal structure and an extended metallic sidewall to stabilise the axial ratio (AR) across a wide bandwidth. This innovative approach has significant potential for phased array applications in ultra-wideband (UWB) circularly polarised environments. Xiong et al. present a novel millimetre-wave two-dimensional (2-D) wide-angle scanning phased array antenna based on decoupling surface. This paper proposes a millimetre-wave phased array antenna capable of wide-angle scanning based on decoupling surface (DS). This proposed design overcomes the challenges of mutual coupling between the antenna elements, enhancing the overall scanning range and efficiency of the antenna array. The proposed antenna exhibits promising capabilities for wide-angle beam-scanning implementation in scenarios such as automotive radar and satellite communication. Liang et al. contribute a high-efficiency wideband co-polarised metalens antenna. The paper demonstrates a multilayer metasurface structure comprising five layers of metal patches and four dielectric layers, forming a Fabry–Pérot resonator. This approach offers a compact solution for integrating metasurface technology with traditional antenna design, pushing the limits of antenna miniaturisation while maintaining its high efficiency. We would like to extend our sincere gratitude to the authors for their outstanding contributions, and to the reviewers for their insightful feedback, which significantly enhanced the quality of this Special Issue. Special thanks are also due to the editorial team at IET Microwaves, Antennas & Propagation for their invaluable support in managing this publication. Data available on request from the authors.

In this paper a new design of Ultra-Wide Band (UWB) generator is presented. This circuit is the most important block in multi-bands transmitter architecture of UWB communication system. The propose...