낮은 높이의 광대역 원형 편파 배열 안테나 시스템을 위한 다층 적재된 실시간 지연 회로와 위상 조절 반사판 설계

학위논문(박사)--서울대학교 대학원 :공과대학 전기·컴퓨터공학부,2020. 2. 남상욱.본 논문에서는 낮은 높이의 광대역 배열 안테나 시스템을 구현하기 위해 필요한 핵심 기술 개발에 관해 연구하였다. 레이더, 전자전, 무선 통신과 같이 많은 분야에서 활발히 사용되는 있는 배열 안테나는 산업이 고도화되면서 요구하는 시스템 스펙이 더욱 고급화되고 있다. 그 중 무인 비행체, 미사일 등과 같은 고속 이동체의 곡면에 배치할 수 있도록 하기 위해서는 낮은 높이의 안테나 설계가 필요한데, 특히 낮은 높이의 광대역 안테나는 구조적으로 설계에 큰 어려움이 있다. 이 논문에서 목표로 정한 응용 분야는 전자전에서 빔포밍을 이용하여 적의 위치를 탐색하고 해당 위치로 특정 주파수의 큰 전력의 신호를 전송하는 전파 방해기이다. 전파 방해기는 광대역의 주파수 대역 내에서 선택적으로 주파수를 선택하여 사용할 수 있도록 설계되어야 하므로 광대역으로 동작하는 시스템 구현이 필요하다. 낮은 높이의 광대역 배열 안테나 시스템는 크게 광대역 빔조향 네트워크와 낮은 높이의 광대역 배열 안테나로 구분할 수 있다. 본 논문에서는 각 부분에서의 문제를 분석하고 이를 해결하여 설계 및 구현하는 방향으로 연구를 진행하였다. 수행된 연구의 내용은 아래와 같다. 첫 번째로, 광대역 빔조향 네트워크를 구성하는 가장 핵심 요소인 실시간 지연회로를 구현할 때 필요한 기술을 개발하였다. 먼저 실시간 지연회로의 중요한 성능 지표인 지연 시간 특성에 영향을 줄 수 있는 3가지 요소들에 대해 분석하였다. 첫 번째 요소는 off 상태에서 보이는 커페시터에 의한 공진이다. 실시간 지연회로에서 공진이 발생하면 전체 시스템 성능이 악화될 수 있기 때문에 30 dB 이상의 격리 특성을 갖는 스위치를 사용하여야 한다. 두 번째로 분석한 요소는 불연속에 의해 나타나는 반사파로 이는 실시간 지연회로와 전체 시스템을 구성할 때 매칭이 필수적으로 수행되어야 하는 이유가 된다. 마지막으로 분석한 요소는 안테나 임피던스에 의한 반사 손실이다. 광대역 안테나의 임피던스는 주파수에 따라 변하게 되는데 이는 안테나에 인가되는 신호의 위상을 변화시켜 배열 안테나 시스템 성능에 영향을 줄 수 있다. 몬테 카를로 시뮬레이션을 통해 안테나 임피던스 변화에 따른 위상 오차가 빔조향각과 사이드 로브 레벨에 얼마나 영향을 주는지 확인하였다. 배열 안테나를 설계하여 해당 안테나의 능동 반사 계수를 통해 이를 검증하였다. 실시간 지연회로의 설계를 진행할 때 추가적인 이슈는 소형화가 있다. 앞에서 분석한 3가지 요소를 고려하여 7-bit 적층 실시간 지연회로를 설계하였다. 제작 및 측정을 통해 설계한 실시간 지연회로가 손실에 따른 지연시간, 높은 bit 수, 저전력의 장점을 가지는 것을 확인하였다. 마지막으로 광대역 안테나 시스템을 구성하여 제작된 실시간 지연회로를 검증하였다. 측정을 통해 제작된 광대역 안테나 시스템이 3:1 대역에서 빔 스퀸트 현상 없이 빔조향이 가능함을 확인하였고 소형화된 실시간 지연회로가 제대로 동작함을 검증하였다. 두 번째로, 낮은 높이의 광대역 안테나를 구현에 필요한 기술로 광대역 안테나 가까이 반사판을 배치하여 단방향 빔을 형성할 때 발생하는 문제점을 분석 및 극복하였다. 낮은 높이의 광대역 배열 안테나에 가장 적합한 안테나는 구현이 쉽고 소형화에 장점이 있는 스파이럴 안테나이다. 양방향 패턴을 갖는 스파이럴 안테나는 단방향 패텅을 만들어 주기 위해 반사판이 필요한데 해당 반사판으로 인해 매칭과 축비에 문제가 생기는 큰 단점이 있다. 본 논문에서는 먼저 반사판이 축비를 악화시키는 이유에 대해 분석하였다. 분석을 기반으로 축비 개선을 위해 varactor를 사용한 polarization-dependent 위상 조절 반사판을 제안하였다. polarization-dependent 위상 조절 반사판이 효과적으로 축비를 개선하는지 확인하기 위해 스파이럴 안테나와 함께 배치하여 설계하였다. 주기 구조를 통해 무한 배열 시뮬레이션을 진행하여 원하는 주파수 대역에서 축비가 효과적으로 개선되는 것을 확인하였다. 이를 구현하기 위해 dummy를 추가한 4 x 4 배열 안테나를 최종 설계하였다. 주기 구조 시뮬레이션과 높은 일치성을 보여 제작 및 측정을 진행하였다. 제작된 안테나의 반사 손실은 원하는 대역 모두에서 -10 dB 이하의 값을 가졌다. 축비, 이득, 패턴 모두 시뮬레이션과 거의 일치한 측정 결과를 얻을 수 있었다. 이를 통해 polarization-dependent 위상 조절 반사판이 효과적으로 축비를 개선하는 것을 검증하였다. 마지막으로 빔조향 특성을 확인한 결과 polarization-dependent 위상 조절 반사판을 적용하면서 손실없이 빔폭 내에서 1.5 dB 아래의 우수한 축비 값을 가지며 -30도에서 30도까지 빔조향이 가능함을 확인하였다. 결론적으로, 본 논문에서는 낮은 높이의 광대역 안테나 시스템을 구현할 때 극복해야 하는 두가지 주제에 대해 분석 및 해결하였다. 정확한 분석 및 적절한 해결 방안을 찾을 수 있었고 이를 통해 광대역 빔조향 네트워크와 낮은 높이의 광대역 배열 안테나에 적용하여 설계하였다. 최종적으로 측정 및 검증을 통해 전체 과정의 타당성을 검증하였다.In this thesis, two essential technologies to realize a low profile wideband phased array antenna system are described. Phased array antennas, which have been actively used in military and civil applications such as radar, electronic warfare (EW), and wireless communications, are becoming more advanced as the system specification demanded by the industry. Especially, low-profile wideband phased array antennas are actively studied. It has been a challenge to design wideband and low-profile antennas, which can be surface-mounted on airborne applications such as missile, aircraft, and unmanned aerial vehicle (UAV) to reduce air resistance. Target application in this thesis is jammer in electronic warfare which is to search the enemy's position and shoot a signal of a large power of a certain frequency to the position by beamforming, so it is designed to selectively choose a frequency in a wide band. The low-profile wideband array antenna system for the application consists of a wideband beamforming network and a low-profile wideband array antenna. In this thesis, we analyzed the issues and problems in each part and overcame them to design and implement the low-profile wideband antenna system. The contents of the study carried out are as follows. At first, design considerations and procedure of wideband beamforming network is presented. Three factors that can affect group delay variation are analyzed, which is the most important performance indicator of the true-time delay line (TTD). First factor that affects group delay characteristic is off-state capacitor resonance. To minimize degradation of TTD performance due to the resonances, switches with an off-state isolation of more than 30 dB are required. Second factor is reflected wave due to discontinuity, so that matching must be accomplished in design of TTDs and all system. The last factor is the phase error caused by the reflection coefficient due to the antenna impedance. Monte Carlo simulations were performed to investigate the effect of phase delay error on the beam steering angle and side lobe level due to antenna impedance. And the actual antenna is designed to verify the effect of the phase delay error on the antenna impedance. Considering these factors 7-bit multistacked TTD was designed and fabricated for miniaturization which is an additional issue when designing a TTD. Fabrication and measurement were performed and our approach shows an improved performance regarding a figure of merit defined as the relative delay divided by the insertion loss at the longest delay state, a large number of bits of resolution, and low power consumption. Finally, a wideband antenna system was constructed to verify the fabricated TTD. Beam steering is performed without beam squint within the 3 : 1 bandwidth, which verify that the miniaturized TTD is capable of wideband beam steering. Second, to solve performance degradation problems when forming a unidirectional beam by attaching a perfect electric conductor (PEC) reflector close to the wideband antenna is described for low-profile wideband phased array antenna systems. The most applicable type of antennas for low profile wideband antenna array is spiral antenna which has advantages of simple manufacture process and miniaturization for array. Spiral antenna has the disadvantage of requiring a reflector for unidirectional patterns due to its bidirectional circular polarized pattern. We analyzed the reason why the axial ratio (AR) could be deteriorated by the reflector first. Based on analysis, a polarization-dependent phase tunable reflector is proposed to implement the required reflection phase of x and y using varactors for improvement of AR. To verify that AR is effectively improved by the polarization-dependent phase tunable reflector, spiral array antenna backed by the polarization-dependent phase tunable reflector was designed and fabricated. Periodic boundary simulation for infinite array and simulation of 4 x 4 array with dummy were performed. A 4 x 4 array with dummy of the fabricated array with polarization-dependent phase tunable reflector for measurement. Fabricated array antenna has a reflection coefficient of less than –10 dB in the entire target band. All measurement results and simulation results have high consistent. AR improvement was achieved through the measurement results by changing bias voltage applied to varactors on polarization-dependent phase tunable reflector. According to this measurement process and results we implemented a spiral array antenna capable of beam steering from -30˚ to 30˚ with excellent circular polarization (CP) characteristics with an AR value of less than 1.5 dB within the 3 dB beamwidth without loss by applying polarization-dependent phase tunable reflector. In conclusion, we investigated and analyzed two issues to overcome for implementation of a low-profile wideband antenna system. Through accurate analysis, appropriate solution could be found and applied to design of wideband beamforming network and low-profile wideband array antenna. Fabrications and measurements were conducted to prove the validity of the entire process.Chapter 1. Introduction 1 1.1. Motivation 1 1.2. Organization of the Dissertation 4 Chapter 2. Wideband Beamforming Network 5 2.1. Analysis of factors that affects group delay variation in TTD 6 2.1.1. Accurate group delay measurement technique in vector network analyzer 6 2.1.2. Off-switch capacitor resonance 10 2.1.3. Reflected wave due to discontinuity 13 2.1.4. Antenna impedance variation over frequency 16 2.2. Design of 7-bit multistacked true-time delay for miniaturization 26 2.2.1. Design considerations 27 2.2.2. TTD resolution and number of bits 30 2.2.3. Optimal design of signal vias 32 2.2.4. Fabrication and measurement results 36 2.2.5. Verification of TTD 40 2.3. Conclusion 53 Chapter 3. Low-profile Wideband Antenna 55 3.1. Analysis of AR deterioration backed by reflector 57 3.2. Improvement of AR with polarization-dependent phase tunable reflector 63 3.2.1. AR improvement through reflector with ideal reflection phase 63 3.2.2. Practical design issues of reflector with varactors 68 3.2.3. AR improvement through 1D phase tunable reflector 76 3.2.4. AR improvement through 2D phase tunable reflector 79 3.3. Design of spiral antenna array backed by polarizationdependent 1D phase tunable reflector 83 3.3.1. Periodic boundary simulation for infinite array 84 3.3.2. 4 x 4 array simulation with dummy 87 3.4. Fabrication and measurement results 90 3.5. Conclusion 107 Bibliography 110 Abstract in Korean 115Docto

Integrated-EBG Ridge Waveguide and Its Application to an E-Band Waveguide 32 732 Slot Array Antenna

A methodology of designing an E-band waveguide 32 732 slot array antenna with high-efficiency and low-cost manufacturing characteristics is proposed in this article, which is based on an integrated electronic bandgap (EBG) ridge waveguide designed by integrating a cross rectangle-hollow EBG structures in the conventional ridge waveguide. The integrated EBG structure intercepts the leakage from the unconnected gap in between the two metallic plates of the waveguide, and then it decreases the manufacturing cost without using the diffusion bonding technology and multi-layer welding assembly process. The design guideline is discussed, and then the antenna is fabricated. The measured radiation characteristics are in good agreement with predicted ones, which confirms that the proposed cross rectangle-hollow EBG structures is an attractive candidate of high-performance millimeter wave antenna

Wideband and UWB antennas for wireless applications. A comprehensive review

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems

Design and Study of a Circular Polarised Conical-Disc-Backed Spiral Antenna for X-Band Applications

Design of a conical-disc-backed circular-polarized Archimedean single-arm spiral antenna is presented in this paper. The antenna operation covers the X-band frequencies ranging from 8 to 12 GHz. The antenna makes use of a very simple structure having the single-arm spiral backed by a cone-shaped metallic disc to achieve high gain, circular polarization, and unidirectional symmetric radiation near the boresight. The diameter of the antenna only measures to 40 mm. The simulated and measured results show that the antenna has a very good impedance matching (better than -10 dB), good right-hand circular polarization (with an axial ratio of ≤3 dB) throughout the frequency range of interest, and offers a maximum peak gain of 11.4 dBiC. The presented S 11 response and radiation pattern results also show that the antenna offers excellent performance in the X-band with no need of a balun. Antenna usefulness is also established through a detailed parametric study and comparison with a traditional flat disc structure. Compact size, simple design, wide range, and high gain make the proposed antenna design a good choice for radar, terrestrial communications, and satellite/aerospace communications applications

Directive antennas based on two-dimensional dielectric EBG crystals

The aim of this work is the design and analysis of novel antennas realised with electromagnetic bandgap (EBG) structures based on simple two-dimensional cylindrical, triangular and square lattices of dielectric rods. In particular, we focused our attention on designing antennas with high directivity and front-to-back-ratio (FTBR) on the azimuthal plane. Several EBG structures have been investigated, divided in two main categories: multilayer EBG structures with an angular defect window and EBG corner reflectors. The former are based on a feeding source excited within a cavity: fields at badgap frequencies are trapped inside the cavity and opening an angular defect window allows propagation in that privileged directions leading to directive radiation patterns. The latter are based on a source placed in front of an EBG corner reflector: at bandgap frequencies, the excited fields are reflected toward the corner aperture (in a similar fashion to metallic corners of analogous dimensions) enhancing radiation patterns’ directivity. The analysed structures have been also modified to host multiple sources to create multiple-feed antenna structures with the ability of rotating the radiation patterns on the azimuthal plane. Antennas have been modelled using an in-house developed Finite-Difference Time- Domain solver and the commercial Finite Element Method solver Ansoft HFSS, focusing on structures designed to operate in the X-band frequency region (8.2GHz-12.4GHz) in order to take advantage of the available equipment and facilities at Heriot-Watt University for prototypes testing. The proposed structures can be nevertheless scaled up or down in size in order to respectively scale down or up of the same factor the frequency of operation. The main achievements of the analysed multilayer EBG structures and corner EBG reflectors are the large impedance bandwidth (greater than 30%) with stable radiation patterns within, high gain (>12dBi) and high FTBR (greater than 25dB) accomplished using EBG structures made with a small number (10-20) of low-loss ceramic rods arranged in very simple two-dimensional crystals. EBG corner reflectors have been also found basically equivalent (at badgap frequencies) to metal reflectors in terms of achieved gain and radiation patterns, suggesting them as possible substitutes for high frequencies applications where dielectric losses would be smaller than metal losses

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

Review on the Design of the Isolation Techniques for UWB-MIMO Antennas

Ultra wide band - Multiple Input Multiple Output antenna technology provides higher data rates and the combination of the ultra wide band (UWB) and the multiple input multiple output (MIMO) technologies provides a solution for the demand of still higher data rates i.e. in excess of 3 Gb/sec in the future.  As the antenna technologies are improving, the size of the MIMO antenna is growing smaller and smaller. Placing the antenna elements in such close proximity increases the coupling between them. Various isolation techniques have to be introduced between the antenna elements to decrease the coupling and to improve the isolation. A study of the various isolation enhancement techniques have been made in this review. It analyses the various isolation enhancement methods such as using orthogonal polarization, parasitic elements, varied decoupling structures, defected ground structures (DGS), neutralization line (NL) and finally by using metamaterials. Metamaterials is a technology to perk up the isolation between the antenna elements. Split ring resonator (SRR) behaves as a metamaterial and it is used as an isolation mechanism in this study. The antennas are simulated and the results are compared. The method using parasitic elements gives the highest isolation of 35 dB and it is 5 dB better than the methods using orthogonal polarization and using the decoupling structure. The performance of all the antennas satisfies the conditions for minimum isolation. The envelope correlation coefficient is nearly zero in all the antennas and it implies good diversity performance. The diversity gain is also calculated for the various antennas and it satisfies good diversity performance. The bandwidth of the antennas is in the UWB frequency range and they have a fractional bandwidth above the required value of 1.09. The capacity loss for all the antennas is very low and the antennas using defected ground structure and the decoupling structure gives very low capacity loss

Recent developments of reconfigurable antennas for 4G and 5G wireless communications: A survey

YesReconfigurable antennas play important roles in smart and adaptive systems and are the subject of many research studies. They offer several advantages such as multifunctional capabilities, minimized volume requirements, low front-end processing efforts with no need for a filtering element, good isolation, and sufficient out-ofband rejection; these make them well suited for use in wireless applications such as fourth generation (4G) and fifth generation (5G) mobile terminals. With the use of active materials such as microelectromechanical systems (MEMS), varactor or p-i-n (PIN) diodes, an antenna’s characteristics can be changed through altering the current flow on the antenna structure. If an antenna is to be reconfigurable into many different states, it needs to have an adequate number of active elements. However, a large number of high-quality active elements increases cost, and necessitates complex biasing networks and control circuitry. We review some recently proposed reconfigurable antenna designs suitable for use in wireless communications such as cognitiveratio (CR), multiple-input multiple-output (MIMO), ultra-wideband (UWB), and 4G/5G mobile terminals. Several examples of antennas with different reconfigurability functions are analyzed and their performances are compared. Characteristics and fundamental properties of reconfigurable antennas with single and multiple reconfigurability modes are investigated.European Union’s Horizon 2020 research and innovation programme under grant agreement H2020-MSCA-ITN-2016 SECRET-722424

A slotted lotus shaped microstrip antenna based an EBG structure

The objective of this paper is to study intensively the design of a printed slotted patch based lotus shape structure mounted on a dielectric substrate backed with an electromagnetic band Gap (EBG) layer for wideband applications. The dielectric substrate is made of a Roger RT/duroid®5880 layer. An EBG layer is introduced on the back profile of the substrate to provide a high gain bandwidth product over wide frequency bands. The antenna is fed with a novel coplanar waveguide (CPW) structure of a flared geometry; therefore, the ground plane is mounted on the same substrate surface with the patch structure. A conductive trace is introduced at the substrate back from the bottom connected to the CPW through two shoring plates to remove the effects of the EBG layer on the feed structure. The EBG performance and the antenna design methodology are discussed using analytical analyses and numerical parametric studies, respectively. The numerical simulation is conducted using CST MWS Finally; the optimal antenna design is fabricated and measured for validation to be compared to the simulated results

Artificial Magnetic Conductor Integrated Textile Monopole Antenna

Wearable antenna is a fast growing field in application-oriented research, which introduced a new generation of garments capable of monitoring wear health, as well as environmental states. This thesis is concerned with the design and fabrication of a compact textile wearable antenna at operating frequency within the Industrial, Scientific and Medical (ISM) band, intended for integration into a flight jacket of the astronaut inside the habitat. The antenna is integrated with artificial material known as High Impedance Surface (HIS) for performance enhancement. The purpose of the system is to constantly monitor vital signals of the astronauts. The entire design cycle of wearable Co-Planar Waveguide (CPW) fed monopole antenna, starting from simulation-based design to fabricated prototype and antenna testing under different conditions was carried out in this thesis. Because of the lossy nature of human body tissues, the radiation efficiency of the antenna will be reduced due to the absorption of the radiated energy. Hence, changes in the radiation characteristics of the wearable antenna like operating frequency, gain and impedance bandwidth will take place. To overcome these challenges, HIS has been suggested and integrated with the monopole antenna to isolate the antenna from the ambient environments. This wearable antenna was tested under real operating conditions such as bending and crumpling conditions. Moreover, as the antenna operates near human body tissues, Specific Absorption Rate (SAR) assessment is required to consider the safety concerns of the antenna system. SAR analysis based on simulation results has been carried out in this thesis to show a significant reduction in SAR with the usage of HIS in the antenna system