The Problems of Ultra Wide Band Antennas Design for High Resolution Radar Application

Abstract-The paper presents the analysis of properties of UWB antennas. It is stressed that conventional approach limited to impedance matching and radiation pattern analysis is often not sufficient in the case of UWB antennas. Distortions of transmitted UWB pulses can degrade performance of a system and thus phase characteristics of the transmission should be taken into consideration too. Having regard to those conditions two antennas are investigated in the paper: the conventional Vivaldi antenna and the designed shielded UWB monopole antenna

Millimeter-Wave Transmitter with LTCC Antenna and Silicon Lens

Millimeter-wave (mm-wave) transmitters are often fabricated using advanced technology and require a sophisticated manufacturing facility. Access to such technologies is often very limited and difficult to gain particularly at the initial stage of research. Therefore, to increase the accessibility of mm-wave transmitters, this study proposes a design that can be assembled in a standard microwave laboratory from commercially available or externally ordered components. The transmitter demonstrated in this paper operates above 100 GHz and is based on a low-temperature co-fired ceramic board in which the antenna array, microstrip lines, and power-supply lines are fabricated in a single process. Different technologies are used to assemble the module, e.g., wire-bonding, soldering, and wax adhesion. Advantages and disadvantages of the proposed design are given based on experimental evaluation of the prototype. Although the performance of the developed transmitter is not as good as that of the similar modules available in the recent literature, the results confirm the feasibility of a mm-wave transmitter that is assembled without employing advanced technologies and superior machinery

A Wire-Bonded Patch Antenna for Millimeter Wave Applications

Wire bonds are one of the most common interconnects used in microelectronics; however, their application to millimeter wave monolithic microwave integrated circuits (MMICs) may severely decrease the overall system performance due to transmission loss, radiation loss, and impedance mismatch. The goal of this work was to optimize a wire-bonded patch antenna to minimize losses and maximize the gain in the frequency range from 81 to 83 GHz. Optimization was based on electromagnetic simulations of different variants of the wire bond. Results show that the optimized structure demonstrates two major advantages. Firstly, it does not require any external matching network; hence, it can be directly connected to a contact pad of an MMIC die. Secondly, the wire bond radiation effect is utilized to enhance the patch antenna gain at the broadside direction

Graphene/AlGaN/GaN RF Switch

RF switches, which use a combination of graphene and two-dimensional high-density electron gas (2DEG) in the AlGaN/GaN system, were proposed and studied in the frequency band from 10 MHz to 114.5 GHz. The switches were integrated into the coplanar waveguide, which allows them to be used in any system without the use of, e.g., bonding, flip-chip and other technologies and avoiding the matching problems. The on-state insertion losses for the designed switches were measured to range from 7.4 to 19.4 dB, depending on the frequency and switch design. Although, at frequencies above 70 GHz, the switches were less effective, the switching effect was still evident with an approximately 4 dB on–off ratio. The best switches exhibited rise and fall switching times of ~25 ns and ~17 ns, respectively. The use of such a switch can provide up to 20 MHz of bandwidth in time-modulated systems, which is an outstanding result for such systems. The proposed equivalent circuit describes well the switching characteristics and can be used to design switches with required parameters

Millimeter-Wave Transmitter with LTCC Antenna and Silicon Lens

Millimeter-wave (mm-wave) transmitters are often fabricated using advanced technology and require a sophisticated manufacturing facility. Access to such technologies is often very limited and difficult to gain particularly at the initial stage of research. Therefore, to increase the accessibility of mm-wave transmitters, this study proposes a design that can be assembled in a standard microwave laboratory from commercially available or externally ordered components. The transmitter demonstrated in this paper operates above 100 GHz and is based on a lowtemperature co-fired ceramic board in which the antenna array, microstrip lines, and power-supply lines are fabricated in a single process. Different technologies are used to assemble the module, e.g., wire-bonding, soldering, and wax adhesion. Advantages and disadvantages of the proposed design are given based on experimental evaluation of the prototype. Although the performance of the developed transmitter is not as good as that of the similar modules available in the recent literature, the results confirm the feasibility of a mm-wave transmitter that is assembled without employing advanced technologies and superior machinery