6220 Culebra Rd, San Antonio, Texas, 78238; 210-522-3827 firstname.lastname@example.org
Southwest Research Institute (SwRI) has developed a reconfigurable, radiationtolerant, communication system that addresses the needs for low-cost, quick turn spacecraft, as well as the reliability and connectivity required in harsh radiation environments of higher orbit systems. The core of such a Flexible Communication Platform (FCP) is a Software Defined Radio (SDR) architecture, currently providing S-Band (2 GHz) communications but expandable to other frequencies. The Digital Processing Unit (DPU) is a PC/104 slice that can be used as a standalone radio with an onboard RF chip for LEO environments or can be augmented with an RF front-end on a separate slice. The architecture of the DPU is based around an SRAM-based FPGA. SRAM-based FPGAs, however, have significant limitations in spacecraft systems due to radiation susceptibility of the FPGA programming cells. SwRI chose to implement a combination of triplicated logic (TMR) and Configuration Memory Scrubbing, specifically in an external RAD-Hard device, to mitigate radiation effects on the system. The flexible design of the DPU all ows rapid integration into multiple target mission architectures. When coupled with the RF front-end, the FCP is capable of communicating from LEO and MEO orbits using a variety of wideband signals and protocols.
usual resonant behaviour. Further, the circular polarization performance is realized with the PIN diodes placement at quadrature angle which leads to the symmetry in the CP radiation with axial ratio below 3 dB with good efficiency more than 80% which can be confirmed through the .The proposed antenna is better suitable for S-bandsatellite and ISM band applications.The gain can be further increased by using array topology.
After the cylindrical DRA had been studied, Long and his colleagues subsequently investigated the rectangular and hemispherical DRAs. In the mid-1990s more study concentrate on linear and planar DRA array from simple two-element arrays to complex phased arrays. This job has developed the foundation to investigate about DRA in future and its applications have been receiving enormous attention in recent years. This is generally found out that the frequency range of interest for so many systems gradually progressed upward to millimeter or near-millimeter range of (200-400 GHz). With this frequency, the conductor loss of metallic antennas becomes very severe and efficiency of antennas is reduced gradually. On the other hand, the DRA loss is due to imperfect dielectric material present in it, practically it is very small in amount. Dielectric Resonator Antennas (DRA‗s) have become popular in recent years because of many advantages they offer like smaller size, ease of fabrication; greater radiation efficiencies, increased bandwidth and lesser production cost, which manifests DRA in different types of Wireless applications. The main objective of this thesis is to introduce a technique to enhance the bandwidth and to reduce the side lobe level using optimization technique; this also decreases the return loss and VSWR.
Reconfigurable antennas have drawn a lot of attention in the wireless communication systems for their multifunctions and additions of freedom degrees. They can dynamically alter their radiation characteristics such as frequency, polarization, radiation pattern, etc. by changing its electrical or physical configuration [1–3]. In this manner, multiple functions can be integrated on a single antenna, resulting in considerable saving in cost and size. Because changing operating frequency while maintaining radiation patterns and polarization could make antenna work in diﬀerent band. If the antenna could change radiation pattern, but maintaining operating frequency and bandwidth, the system performance will be greatly enhanced. Manipulation of an antenna’s radiation pattern can be used to avoid noise of sources, improve eﬃciency by directing signals only toward intended users. Polarization diversity is used to avoid the detrimental fading loss caused by multipath eﬀect. Many microstrip reconfigurable antennas have been proposed in the past that use pin diodes , copper strip  or MEMS switches [6, 7]. However, compared with conventional semiconductor-based passive devices, MEMS technology enables the realization of RF passive components with low loss, high isolation, small size, low power consumption, high quality factors, high tunable characteristics and high linearity. So in recent year, MEMS switches are used broadly in reconfigurable antennas [8–10], but most of which work in low frequency. Compared with low frequency antennas, millimeter band antennas have several advantages. First, antennas can be more directive with the same aperture size. Second, it greatly reduces the size of the antenna, which is more suitable for the combination with MEMS devices. Finally, Ka- band antenna, compared to C-band and Ku-band, provides more powerful data throughput, which can be applied to satellite communication .
Computing power in space has been limited in the past by the need to qualify a design early in the acquisition process, in order to ensure that the processor will operate properly in the space environment for the lifetime of the satellite. As today’s information technology continues to expand according to Moore’s law , spacecraft designers are limited from using the most current technology. Additionally, hardware designs must be completed, tested, and software written for vital spacecraft functions within the design/acquisition timeline. This problem is mitigated to a degree by the use of Field Programmable Gate Arrays (FPGAs). A “hardware” configuration is stored in memory elements in an FPGA, and FPGAs are reconfigurable. This allows for testing and qualifying the actual hardware, but also allows for continued development of the application configuration that will be instantiated on the FPGA. These save time and money in the design of systems, as well as redesign costs to fix errors. The trade space with FPGAs, though, is reliable computing.
SMALL satellites are becoming increasingly popular due to their low cost, minimized volume, reduced design and advance time and then digital filters are the essential part of microwave satellite communications, modern wireless communications and electronic system because it can eliminate the harmful constituent from signal. FIR equiripple filters have developed as a strong option for removing noise, shaping spectrum and minimizing inter-symbol nosiness in satellite communication architectures.Communication satellites can be classified into seven main categories. They are large satellite>1000kg, medium satellite 500-1000kg, mini satellite 100-500kg, micro satellite 10-100kg, nano satellite 1- 10kg, pico satellite 0.1-1kg and femto satellite <100g. Smallsatellite system remains the same of classical communication satellite and that are both efficient and accurate when applied to communication paths. Low power consumption and small size are required for smallsatellite which stays an international project sharing among IRAN, CHINA, THAILAND and numerous Asian countries. Small satellite’s dimensions and mass does not differ from large ones, including practically the same functions. Classical satellites are large, expensive and process of their building lasts for many years and therefore small satellites are playing a very important role in the field of remote sensing, navigation and surveillance and it necessities the use of commercial off the shelf (COTS) elements so they can be used in a lot of applications such as earth observation, education, military applications, distance learning, telemedicine, universal access, disaster recovery and television transmission in many tropical regions.The frequency band used in this system is C band because they are mainly used for numerous Asian countries. This paper is organized in the following sequence. Section II describes C bandsmallsatellite uplink model with its block diagram and classification of frequency band. Section III is about digital filter and FIR. Design calculation and filter parameters are presented in section IV. Simulation results exist in section V
Due to the rapid growth in the communication system the demand of frequency band increase that leads to scarcity in the RF spectrum. Mainly, the scarcity of RF spectrum arises due to the inefficient spectrum allocation. As the frequency bands are used more, the cognitive radio (CR) comes into account. To overcome the future communication problems cognitive radios are used which improves the spectrum usage efficiently. CR has the capability to use the unoccupied space in a wide frequency range by sensing and detecting the available channels before initializing communication. The development of the CR puts a great challenge to antenna design. In general, the introduction of CR and allocation of spectrum offers new challenges to the frequency reconfigurable antenna as the antenna can tune the frequency without sacrificing the gain and radiation properties. There is one way to overcome this solution that integration of reconfigurable filter to the antenna structure which is known as filtenna which can be integrated at the feeding line or also on the ground plane of the antenna. Most of the reconfiguration mechanisms are integrated into the ultra-wide band (UWB) antenna in order to operate in multiband. It can be done by using some switches such as ideal switches, optical switches, p-i-n diodes, varactor diodes, linear actuators and also stepper motors are used for rotation of patches. The p-i-n diode switches acts as resistances to the flow of current and requires large amount of DC power for its operation to
mismatches that can arise from the use of two separate oscillators, since these would need individual LC tanks that are physically apart on the IC, and require distinct routing to the circuit driven by the oscillators. The architecture employed here is similar to . However no implementation and measurements were included in . This work also employs a customized spiral inductor or reducing die area. Unlike this work, the active core reconfiguration shown in  was employed to generate two widely separated frequencies. Switching that employ different architectures include  and , that effectively switch mutual inductance of multiple inductors to implement switching mode oscillators; a triple band oscillator with active core switching ; and a mode switching oscillator based on switching capacitance .The minimum size of the switches that is required to ensure transition from one mode to another is also analyzed. It is important to minimize switch size, since this helps to minimize the associated capacitive parasitic.
led to the development of multi-band platforms capable of accessing these wireless services. A major benefit of a reconfigurable antenna is the capability to access multiple services in a device without the need of multiple antennas, thus potentially saving space. In many of the reconfigurable antenna designs in published literature, PIN diodes, RF MEMS switches and optical switches have been used to reconfigure the antennas  - . Furthermore, microstrip patch antenna arrays are of great interest because of their small size, low cost, light weight, ease of manufacturing and useful radiation patterns . Typically, series-fed antenna arrays are driven from a single point and the radiating elements are connected in series by using conventional transmission lines of suitable length for the operating frequency. These transmission lines can be replaced by meandered-lines and drive the elements of the array with the same voltage phase in order to achieve a broadside radiation pattern. However, at low microwave frequencies meander-lines can be very large. A possible way to overcome this size problem is to incorporate composite right/left-handed transmission lines (CRLH-TLs) into the feed network of a series-fed antenna array -. Eﬀorts have been made previously to minimize the overall size of an array using CRLH-TLs , -; however, these designs were limited to a single band of operation.
In this paper, a novel frequency reconfigurable E- shaped patch antenna design is presented as a new wide- band patch antenna for possible use in cognitive radio systems. This design could be used in wireless applications such as Laptops, Wi-Fi, Bluetooth, and ZigBee etc. E – Shaped patched design offers a simple single layer single feed structure that is straight forward to manufacture. It provides the accessibility by using the slots for the bias lines to control the switches. A reconfigurable dual-band antenna for wireless applications with very wide range tenability has been proposed by N. Behdad . A reconfigurable patch antenna for satellite and terrestrial application has been reported .
The measured and simulated radiation pattern of the antenna at two operating bands are presented in Fig 7 and 8. The circular polarization can be clearly observed in LHCP and RHCP from the obtained results. Simulated and measured axial ratio values at both the operating bands can be observed from Fig 9. A slight variation in the normal operating bands and the axial ratio operating bands can be understood from the achieved results. Fundamental resonating band is shifted from 2.5 to 2.6 GHz and second resonating frequency is shifted from 3.4 to 3.5 GHz.
Abstract—A novel miniature microstrip-fed multiband antenna for wireless local area network (WLAN) and X-bandsatellite communication applications is presented in this paper. The proposed antenna consists of two arc-shaped strips, dual inverted L-shaped parasitic stubs, and a partial ground plane. The proposed antenna can excite multi-resonant modes while achieving a compact size of 18 × 34 . 5 × 0 . 8 mm 3 . The measurement results show that − 10 dB impedance bandwidths are 290 MHz (2.28–2.57 GHz), 1.27 GHz (5.0–6.27 GHz), and 850 MHz (7.11–7.96 GHz), which can cover the entire operation frequencies of WLAN (2.48–2.4835 GHz, 5.15–5.875 GHz) and X-bandsatellite communication system (7.25–7.75 GHz) applications.
Then, a new resonant frequency at 0.9 GHz can be generated by the meandered shorting strip (strip1) which is connected to ground plane through a via, and the new structure is called antenna B. The high frequency band of antenna B does not conform to the demand of 1.8 GHz band. Therefore, a shorting strip (strip2) is added on the other side of substrate for the proposed antenna, which can excite a resonant mode at 1.7 GHz to increase the bandwidth of middle frequency band. Besides, for easy adjustment of parameters among the coupling elements the inverted-L shaped monopole, strip1 and strip2 are designed non-overlap between front and back sides of the substrate. The multiband antenna for LTE/WWAN/WLAN applications is achieved from the above design process.
Another drawback of the conventional systems measurement is its inaccuracy due to amplitude-phase conversion (AM-PM) in the case of a high level measurement signal fed through a filter into a nonlinear amplifier. furthermore, the conventional system using frequency modulated signal has a high spectral density, which may under certain circumstances, lead to interference with the adjacent satellite system and can degrade the quality of the other user signal.
In this type of feed technique, the radiating patch and the microstrip feed line are separated by the ground plane. Coupling between the patch and the feed line is made through a slot or an aperture in the ground plane and variations in the coupling will depend upon the size i.e. length and width of the aperture to optimize the result for wider bandwidths and better return losses. The coupling aperture is usually centered under the patch, leading to lower cross-polarization due to symmetry of the configuration. Since the ground plane separates the patch and the feed line, spurious radiation is minimized.
The proposed Antenna Gain can be improved to increase the distance of coverage.EBG structures can be investigated to improve the Gain and Bandwidth for all the three frequency bands of interest.For cognitive Radio based applications where multiple narrow frequency bands are required for transmitting and receiving the information,our proposed Antenna can be a solution.
Abstract: In this article, a small dual band rectangular slot antenna for broadband application is presented. The antenna is being excited by capacitive coupled probe feed. The antenna consists of rectangular slot from the center of the patch. The rectangular slot is being used to obtain dual frequencies of 2GHz and 3.34GHz. Instead of a rectangular feed strip; antenna is excited by a triangular feed strip with same dimension. Triangular feed strip is used to obtain a broad band dual frequency range. The gain of the antenna obtained at particular frequency range is above 5dB so the antenna works well in the particular frequency. Along with Triangular feed slot is also being added in the patch. The size of the antenna is 100×100×1.6mm 3 with the ground of same dimension. The proposed antenna is simulated and optimized using IE3D simulation software.
proposed for various communication applications in S-band, C-band and X-band. The proposed antenna has a defective ground structure (DGS) to improve the performance of the antenna. The ground plane has L-shaped slots and the patch consists of a rectangular slot to enable multi frequency band operation. This antenna is designed on FR4 substrate with dielectric constant 4.4, thickness 2 mm with dimensions of 40 X 40 X 2 mm3.The design of the structure and result analyzation is carried out using High Frequency Structural Simulator (HFSS) software. The proposed antenna exhibits return loss of -24dB, -21dB, -13dB, -16dB, -19dB, -15dB, -12dB, -15dB at 3.2GHz, 4.6GHz, 5.6GHz, 6.6GHz, 8.1GHz, 9.1GHz, 10.1GHz, 11.6GHz respectively with VSWR < 2 for all the eight bands. The observed results suggest that the proposed antenna can be employed for multiple wireless communication applications.
Today FPGAs are widely used in product prototyping and development because of their ability of configuration and re- configuration. FPGAs have a regular structure of logic blocks and interconnect which facilitates for making it a fault tolerant system. With the development in the integrated circuit technology and increase in logic density, FPGAs have become more vulnerable to faults like any other IC chips. SRAM based FPGAs are prone to both transient (single event upsets) and permanent faults. Faults may occur anywhere in the device. Many researchers have developed techniques for handling these faults. FT system design involves mainly three phases, fault detection, diagnosis and correction of faults. Testing is done for finding the faulty component and diagnosis is needed for locating the fault. Once faulty part is identified, repair process is done without disturbing normal function of the system. Factors considered by researchers while developing FT technique are i) area overhead ii) latency period iii) reliability etc
The proposed letter contains an antenna which well suits in the application area of military, satellite, terrestrial, radar and civilian applications in the X band which is designed using High Frequency Structure Simulator (HFSS). This letter is organized as Section II which discusses the Antenna Design Procedure, followed by Section III which presents the Results and Discussion and Section IV concludes the paper with Conclusion.