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Reconfigurable Antennas and their Applications
Full text linkOne of the biggest challenge in modern communication systems is to provide a single antenna for different applications. Existing antenna systems are limited to some applications. So it is important to design a single reconfigurable antenna for multiple applications.
Five different reconfigurable printed antennas for different applications are designed during the study of this thesis. In the first design an antenna for frequency reconfigurable applications is designed. The electrical length of the conductor is changed using PIN diodes and the resonance of antenna is shifted from 4.27 GHz to 3.56 GHz. Good agreement between simulated and measured results is observed. In the second and third designs, Ultra wideband (UWB) Multiple-Input Multiple-Output (MIMO) antennas with on-demand Wireless Local Area Network (WLAN) rejection are designed. The second design consists of two elements UWB-MIMO antenna and stubs are connected to the ground plane using PIN diodes. These stubs act as a stop-band filter and reject the band at 5.5 GHz center frequency. This design has a compact size of 23 x 39.8 mm2. The third design has almost same features as of second design but it has four elements. These elements are placed orthogonally to each other. The total size of this proposed design is 50 x 39.8 mm2. The ground plane is common and a band-stop design is placed between the ground planes. This band-stop design is connected with the ground plane using PIN diodes. When diodes are biased, the current is travelled to the nearly placed band-stop design and a notch is obtained around 5.5 GHz. In fourth design a reconfigurable array with a sensing circuit is designed. The array consists of four individual reconfigurable patches which are attached to the different conformal surfaces. These patches are reconfigured from 3.15 GHz to 2.43 GHz using PIN diodes. The correct phase at each element is provided using phase shifters. The sensing circuit is designed in such a way that only input voltage is changed to provide the correct phase on the switching frequency. The patterns of the array are recovered on both switching frequencies when array is attached to wedge or cylindrical surface. In the last design a series-fed array is designed. Composite Right/Left Handed Transmission Line (CRLH-TLs) are used instead of traditional meanderline microstrip lines to connect the array elements. These CRLH-TLs provided the zero phase at each connecting element, which resulted in broad side radiation patterns. To reconfigure the antenna to another frequency a small patch and second CRLH-TL is connected between array element
3-18 GHz compact planar antenna for short-range radar imaging
No full textAn ultra-compact planar antenna aiming to be part of an imaging antenna array operating in the broad 3-18 GHz frequency range is presented. The antenna is made of two closely packed wide-band monopoles for simultaneous transmission and reception functionalities. A high isolation (> 20 dB) between the two patches is achieved through the insertion of a structured ground plane (decoupling structure). A prototype was fabricated on a Roger R4003c laminate measuring 58 mm2 x 33 mm2 and used in inverse synthetic array radar configuration for detecting a steel object with sub-centimetre spatial resolution
Compact ultra-wideband diversity antenna with a floating parasitic digitated decoupling structure
No full textA compact planar ultra-wideband (UWB) multiple-input-multiple-output antenna array with two radiating elements is proposed in this work. Elements separation is kept at 5.5 mm and the isolation is achieved with a floating parasitic decoupling structure not known for UWB diversity antennas previously. The antenna system performs very well over the entire UWB frequency range of 3.1-10.6 GHz. The mutual coupling between the radiating elements is below -20 dB in most of the band. The decoupling structure is investigated in detail and the diversity analysis of the antenna in Rayleigh fading environment for indoor and outdoor propagations is also presented by computing envelope correlation coefficients. The proposed antenna array measures 33 x 45.5 mm(2) only and it is suitable for handheld devices, personal digital assistant (PDA)s, next generation home entertainment systems and robots
A compact dual polarized ultrawideband multiple-input- multiple-output antenna
No full textA multiple-input-multiple-output (MIMO) antenna with dual polarization, operating in the UWB frequency range is proposed. The radiator is shared by the two antenna elements, which greatly reduces the overall size of the MIMO antenna system. Slots are etched in the radiator to achieve the desired isolation among the elements. Dual polarization characteristics of the radiator are attained in the far-field due to orthogonal currents. The comparison of simulated and measured results show that the proposed MIMO antenna operates on a wide range from 3 to 11 GHz with a low mutual coupling (<-15 dB) and also a low envelope correlation coefficient. A prototype was fabricated on low loss Rogers TMM4 laminate measuring only 25 × 27 mm2, which is a very compact design
A Miniaturized Dual-Band MIMO Antenna for WLAN Applications
No full textThis letter reports on a compact planar dual-band Multiple-Input and Multiple-Output (MIMO) antenna for Wireless Local Area Network (WLAN) applications. The proposed antenna primarily consists of two meandered monopole radiators that are decoupled by introducing a folded Y-shape isolator element and it is shown that the edge coupling between the radiators and isolator introduces the resonance at the lower band. The miniaturization is achieved by passing the signal on to the bottom layer where a meandered line conductor introduces a broadside coupling with the radiator, originating the higher band resonance. The antenna operates between 2.4 GHz to 2.5 GHz and 5.45 GHz to 5.65 GHz with an isolation of more than 25 dB and 15 dB, respectively. The antenna measures only 19x23 mm^2
Isolation enhancement of a wideband MIMO antenna using floating parasitic element
No full textA Multiple-input multiple-output antenna array with two radiating elements having a wide bandwidth is reported in this work. Spatial diversity has been introduced to achieve the diversity gain and the array was kept compact by introducing five parasitic decoupling elements on the bottom of the substrate; each having a length equal to λ/2 at a specific frequency. Each resonant element offers a resonant bandwidth of 1 GHz starting from 3 GHz to 8.5 GHz. Good agreement between the measured and simulated results shows that the antenna system performs very well over the frequency range 3 GHz to 8.5 GHz. In addition, an isolation of more than 15 dB is achieved with the help of the parasitic elements, while keeping an edge-to-edge and center-to-center separation of 4 mm and 19 mm, respectively. The proposed antenna measures 26 × 40.5 mm2, and it is suitable for handheld devices, personal digital assistants, next generation home entertainment systems, and robots
An Integrated Microwave Imaging Radar With Planar Antennas for Breast Cancer Detection
No full textThe system design of an integrated microwave imaging radar for the diagnostic screening of breasts cancer is presented. A custom integrated circuit implemented in a 65-nm CMOS technology and a pair of patch antennas realized on a planar laminate are proposed as the basic module of the imaging antenna array. The radar operates on the broad frequency range from 2 to 16 GHz with a dynamic range of 107 dB. Imaging experiments carried out on a realistic breast phantom show that the system is capable of detecting tumor targets with a resolution of 3 mm
A Frequency-Reconfigurable Series-Fed Microstrip Patch Array with Interconnecting CRLH Transmission Lines
No full textThis letter presents the design of a frequency-reconfigurable series-fed microstrip patch array in which the elements are interconnected with composite right/left-handed transmission lines (CRLH-TLs). Reconfigurable CRLH-TLs are used instead of meandered microstrip lines to reduce the overall size of the array and provide two different zero-phase frequencies of operation for broadside radiation in both instances. p-i-n diodes were used to reconfigure the array by changing the electrical lengths of the patches and microstrip sections of the CRLH-TLs. The measurements were taken in an anechoic chamber to verify the simulation results. The array can be reconfigured to operate at 1.97 and 2.37 GHz
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