GHz Coverage Research Articles

2.5 GHz to 3.5 GHz fractal metasurface microstrip antenna design for high bandwidth wireless applications

In this paper, the microstrip slot antenna is designed for a wireless application with fractal structure having 2.5 - 3.5 GHz coverage and 30% bandwidth. The circular slot antenna with seven triangular slots is considered and six single rings are added to the antenna. As a last step, the enhancement of the matching is produced by a disk located the central part of the slot. The fractal model improves the bandwidth, modifies the antenna matching and controls the current distribution in such a way that it is used in the S (short) band in our case for WiMAX technology, which allows wireless transmission of voice, data and video in areas of up to 48 km radius. It was projected as a wireless alternative to ADSL and cable broadband access, and a way to connect Wi-Fi nodes in a metropolitan area network. The antenna gain is about 19.37 dB with a compact size of 60 × 60 mm2. The metasurface structure helps us to improve the bandwidth. The antenna was simulated with Ansoft Designer V.3.5. The antenna is designed in FR4 as the most suitable material as well as being low cost and accessible. It is proved that the fractal shape is used to improve the bandwidth. The result of combining the metasurface with the antenna can be considered to improve the bandwidth

An ultra-wide band printed small aperture tapered slot phased array antenna covering 6-18GHZ

For phased array applications covering ultra wide bandwidth, it is necessary to restrict the size of the aperture to less than λ/2 at highest frequency of operation. For 6-18 GHz coverage, an aperture size of less than 9.76mm is required for scanning to ±450 without appearance of grating lobes and occurrence of element pattern nulls over the band. Meeting this requirement a printed tapered slot antenna has been designed with the above aperture size. Detailed parametric studies have been carried out over 6-18 GHz and dimensions have been opti-mized for return loss. The design has been carried out with HFSS software. A return loss of less than -7.5dB across 5.6 - 20 GHz has been obtained for a single antenna. Also satisfactory radiation patterns have been obtained.

Frequency locked loop architecture for phase noise reduction in wideband low‐noise microwave oscillators

A frequency locked loop (FLL) for phase noise reduction of wideband voltage controlled oscillators is proposed. The key building block of the system is a low noise (−160 dBV/Hz) and high sensitivity (22 V/GHz) delay line frequency discriminator with 5–8 GHz coverage, which makes use of a high performance multilayer hybrid. The authors derive closed-form, universal design equations for the maximum noise reduction and stability of the FLL circuitry. Application of the proposed technique to a state-of-the-art voltage controlled oscillator operating in the 5–8 GHz band yields a phase noise reduction of 8–10 dB at 100 kHz and 5 dB at 1 MHz off the carrier, which shows the results are in good agreement with the simulated results; so phase noise better than −107 dBc/Hz at 100 kHz and better than −123.5 dBc/Hz at 1 MHz is obtained.

Utilizing a Test Lab For Wireless Medical Devices

Changes in healthcare suggest that more and more medical devices will begin to utilize the information technology (IT) network infrastructure in the hospital, particularly the wireless network. Due to the increased risk of operating medical devices on the converged wireless IT network, there are multiple steps required to safely and effectively implement these types of devices. A key component of the implementation should be to perform testing of wireless devices for interference and functionality. In order to perform this testing, development of a test environment within the hospital is required. While recent focus has been on electromagnetic interference and the risk assessment and mitigation via IEC 80001-1— the new standard for the application of risk management for IT networks incorporating medical devices—more progress is needed in the development of a test lab and performance of testing within the hospital environment. There are many potential benefits of deploying medical devices on the wireless network; however, there are multiple risks, including loss of data or missed patient alarm notification due to a loss of wireless network connectivity. Testing can be vital in identifying and developing mitigations for these risks. Creating the Lab In order to create a test lab, a location first must be selected. In theory, an ideal wireless test environment would be shielded from all external sources of radio frequency (RF) interference. To achieve this goal, physical space and a substantial budget would be required. A stand-alone wireless network infrastructure would have to be developed in this shielded space to enable the connection and testing of any wireless medical devices. This type of test environment is impractical for clinical engineering use due to resource constraints and the inadequacy for realistic simulation of the true deployment environment. A more realistic and beneficial location to create the test lab would be a clinical engineering shop or a storage area in the basement of the hospital. The value of this type of location is that the physical space is relatively distant from clinical floors, thereby limiting the interference between the current patient-care equipment and the test lab and reducing the potential risk to either the device under test or to the devices on the clinical floor. It is also advantageous to be in the hospital in order to utilize a segregated portion of the network infrastructure that is already in place. Also, although a test lab in this environment would not be totally isolated About the Author

The Phoenix signal detection system

The Phoenix system is based on that developed for the Targeted Search element of the former NASA High Resolution Microwave Survey (HRMS). The Phoenix system was used at the Parkes 64 m and Mopra 22 m antennas of the Australian Telescope National Facility in the first part of 1995. The system consists of: (1) an RF/IF subsystem providing 1–3 GHz coverage; (2) a search subsystem with a 20 MHz, dual-polarization search bandwidth; (3) a two-site, pseudo-interferometric follow-up subsystem that reobserves interesting signals found by the search subsystem; and (4) a control subsystem capable of automatic searching.