Microwave Communication

The design of micro strip antenna is vital study for today's wireless communication system to achieve compatibility. Research and development in micro strip antenna, exploiting their advantages such as low weight, low volume, and low cost, conformal configuration compatibility with integrated circuits. This paper presents a proposed design for Rectangular micro-strip patch antenna by cutting a rectangular slot of (2*30) in the Rectangular patch which operates at two central frequencies 1.4, 2.37GHz. Field generated by this slot should be additive in the nature so that we are able to radiate electromagnetic radiation properly, which is a new dual frequency micro strip antenna. Basically micro strip patch is having small bandwidth and can be operated at single frequency. Return loss, VSWR and bandwidth has been found by different micro strip feeding technique. All available feeding technique are micro strip, aperture coupled, proximity feed etc. For the design of the micro strip antenna FR-4 substrates which have permittivity of 4.4 and thickness 3.2, loss tangent is 0.02 has been used. We are using FEKO simulation software for designing and analysis. We have observed that using slotted patch antenna and using micro strip at proper location we can get better return loss, VSWR bandwidth and multiband.

The design of micro strip antenna is vital study for today's wireless communication system to achieve compatibility. Research and development in micro strip antenna, exploiting their advantages such as low weight, low volume, and low cost, conformal configuration compatibility with integrated circuits. This paper presents a proposed design for Rectangular micro-strip patch antenna by cutting a rectangular slot of (2*30) in the Rectangular patch which operates at two central frequencies 1.4, 2.37GHz. Field generated by this slot should be additive in the nature so that we are able to radiate electromagnetic radiation properly, which is a new dual frequency micro strip antenna. Basically micro strip patch is having small bandwidth and can be operated at single frequency. Return loss, VSWR and bandwidth has been found by different micro strip feeding technique. All available feeding technique are micro strip, aperture coupled, proximity feed etc. For the design of the micro strip antenna FR-4 substrates which have permittivity of 4.4 and thickness 3.2, loss tangent is 0.02 has been used. We are using FEKO simulation software for designing and analysis. We have observed that using slotted patch antenna and using micro strip at proper location we can get better return loss, VSWR bandwidth and multiband.

The .carcity of .uitabZe radio qectrvm for indoor Ndio communicatio~ under tM 'regulatory co~trAinu Au prompted endeavor. to inve.tigate mean. of utilizing tM vcduable channel bandwidtA. aVAilable tDitlr.in _ thue condrAinu. The interference potential of the mi-cro1Uave oven u chaNCterUed in an attem.pt to render the ISM band it Oc.cupied weful for indoor radio com-municatio~. The chaNCterUation procu. included an in-depth power qectral metuu'rement of the rtldiation. .A theoretical model of the radiation clr.aNCteridic. u _ tMn propo.ed. The interference clr.aNCterizGtion re-nUt. point to a po"ible valuable frequency bandwidth t/ud may be available for high Ipeed indoor communic~ tion. wage in the "low cod-connmer product a'renG.

... Cherniakov, M., Kubik, KKT and Nezlin, D. (2000) Radar sensors based on communication low earth orbiting satellites microwave emission. Proceedings IGARSS 2000, IEEE 2000 Int. ... The University of Queensland. Brisbane St Lucia, QLD 4072 +61 7 3365 1111. ...

Wide bandgap semiconductors are extremely attractive for the gamut of power electronics applications from power conditioning to microwave transmitters for communications and radar. Of the various materials and device technologies, the AlGaN/GaN high-electron mobility transistor seems the most promising. This paper attempts to present the status of the technology and the market with a view of highlighting both the progress and the remaining problems.

Fade depth prediction on airborne line-of-sight communication links is considered. There is no specific model for this scenario at the moment. The two ray multipath model, adapted to a realistic scenario of hilly or mountainous terrain, was used to account for flight and terrain geometry and for antenna parameters. Surprisingly, it was found that (i) in many practically important cases the fade depth depends on the path clearance angle only and (ii) the two-ray model predicts roughly the same fade depth dependence on the path clearance angle as the well-known Olsen-Segal model. This may be considered as a theoretical justification, to the best of our knowledge for the first time, of the path elevation angle factor in that model

This communication reports the first ever use of the over ocean evaporation duct to implement a high-capacity radio link from the Australian mainland to the Great Barrier Reef (GBR), North Queensland, Australia. Conventional long-distance radio communication techniques such as high-frequency (HF) radio, satellite, or cell phone are either too slow or too expensive to operate continuously in this situation. A microwave radio link overcomes these problems but would generally not be viable due to the limited range possible with a standard line-of-sight microwave link. This communication shows that by properly choosing the antenna height and operating frequency though, it is possible to trap signals in the ocean evaporation duct and substantially extend the propagation range. A 78-km link that operates at a frequency of 10.6 GHz and provides a data rate of 10 Mb/s has been established to verify the technique. The communication also provides preliminary results of the measured performance of this link and a comparison with existing radio propagation models.

A new general outage probability expression for a Rician signal received among L Rician interferers is derived. This result is shown to cover previous published expressions involving Rayleigh signal/interferers as special cases. A new method is then applied to further extend the result to include the effect of lognormal shadowing on the outage probability. New Rician/Rician outage probability curves against the normalized reuse distance and cluster size with and without lognormal shadowing effect are presented and discussed.

Microwave communication is still important to use in the backhaul network of telecommunications systems because it can reach remote areas that are difficult to reach by cable technology. One of the implementations is cross-ocean backhaul communication which is widely applied in the archipelago. So, to reach the remote areas, proper backhaul network planning is required. A point-to-point microwave transmission network can be a solution to reach remote areas of islands separated by oceans. The problem that occurs is that the multipath fading on the ocean route is quite large so that to overcome this we need a diversity technique. There are various diversity configurations such as space, frequency, and a combination of both or Hybrid. Based on the simulation and theoretical calculations, concluded that point-to-point configuration producing the quality of communication below the standards set by the ITU-R (ITU-T G.821). The use of space diversity and hybrid diversity provided a significant increase in the quality of communication both in terms of availability, unavailability, and fading margin.

Wide bandgap semiconductors are extremely attractive for the gamut of power electronics applications from power conditioning to microwave transmitters for communications and radar. Of the various materials and device technologies, the AlGaN/GaN high-electron mobility transistor seems the most promising. This paper attempts to present the status of the technology and the market with a view of highlighting both the progress and the remaining problems.

A new direct-conversion wide-band (23-31 GHz) six-port receiver is proposed suitable for millimeter-wave integrated system design. This new hardware receiver is found to be robust, rugged, low cost, and suitable for use in broad-band wireless mass-market QPSK communications. The prototype circuits are fabricated to validate this new concept with our miniaturized hybrid microwave integrated-circuit technology and the proposed receiver topology is also suitable for monolithic-microwave integrated-circuit fabrication. This application-specific integrated receiver is designed on the basis of a wide-band six-port junction and other analogical circuits in the form of a simple multichip module. Bit-error-rate measurements and simulation results are shown and discussed in the presence of noise, adjacent signal interference, local-oscillator (LO) phase shift, and LO phase noise. The maximum bit rate is fundamentally limited by the speed of the video and decoder circuits. Nevertheless, several hundred megabits per second can be achieved at low cost.

This paper proposed new system architecture for Mobile Ad Hoc Networks (MANETs) on heterogeneous network to provide optimal Video on Demand (VoD) services to difference types of devices with optimal bandwidth utilization. And at the same time it will provide separate VoD services to different type of devices. and proposed a new conceptual model whereby a MANET node is possible to move through heterogeneous networks and infrastructures, there are also several nodes connected and receiving VOD services in different communication and infrastructural approach also we proposed for our system architecture Global Media Forwarder to provides wide area services through deployed infrastructures such as 3G and WIMAX as well as a new protocol call (DNDS) will be used for accumulating the required information from the MANET nodes and Media Forwarders for configuring and providing optimal services to the MANETs users, implemented and executed between Media Forwarders, CVSP and the MANETs nodes.

The integration of ICT in vehicular environments enables new kinds of application and creates new technological challenges. Dynamic network topology, unreliable network links, and moving terminals make it hard to provide a convincing end user experience. This article introduces the concept of providing trustworthy applications through wireless networks in vehicular environments. A special emphasis will be on how to maintain end users privacy when providing personalized, contextaware services. Therefore, a service taxonomy, enabling middleware technologies, and service enablers are introduced.

The feasibility of compensating for reflector surface distortions has been Investigated. The performance characteristics (gain, sldelobe level, null location, beamwldth, etc.) of space communication reflector antenna systems degrade as the reflector surface distorts due to thermal effects from a varying solar flux. The technique reported here will maintain the design radiation performance Independently of thermal effects on the reflector surface. With the advent of monolithic microwave Integrated circuits (MMIC), a greater flexibility 1n array-fed reflector system design can be achieved. MMIC arrays provide Independent control of amplitude and phase for each of many radiating elements of the feed array. The conjugate field matching technique provides a basis for obtaining the required element excitations under surface distortion for maintaining the design radiation performance. It 1s assumed that the surface characteristics (x, y, z, first derivatives, and second derivatives) under distortion are known.

For a directional (a.k.a. directive) transceiver misaligned towards an omni-directional transceiver, the multipaths' time-of-arrival (TOA) distribution is herein derived in closed form explicitly in terms of the "geometric modeling" parameters. This derivation allows the directional beamwidth to mis-point to any arbitrary azimuth-direction, even if entirely away from the intended omni-directional transceiver.

Beam loading of a cavity is mostly computed under the assumption of an infinite axial magnetic field. In practice, a finite focusing magnetic field is almost always present. In this paper, we extend Branch's classic paper [I] on ballistic bunching in that

The Recirculating Planar Magnetron (RPM) is a novel crossed-field device whose geometry is expected to reduce thermal load, enhance current yield as well as ease the geometric limitations in scaling to high RF frequencies as compared to the conventional ...

A phase conjugation based method for full-duplex digi-tal communications is discussed. The method uses a spa-tially confined and directive antenna pattern while a full-duplex digital communications link is maintained between moving platforms. The communications abilit ~ of the array is based on processing the phase associated with the mes-sage and the phase associated with the platform’s motion separately. Preliminary measurements at 6 GHz indicate that the phase conjugation method does allow simulators tracking and communications.

There has been a flourishing prospect of UWB technology in recent years in both communication and other purposes like microwave imaging and radar applications. Antenna in UWB imaging systems plays a significant role and it is quite challenging to design a proper antenna satisfying all the constraints required for microwave imaging applications. Recent studies of UWB antenna structures are specially

this paper proposed new system architecture for Mobile Ad Hoc Networks (MANETs) on heterogeneous network to provide optimal Video on Demand (VoD) services to difference types of devices with optimal bandwidth utilization. And at the same time it will provide separate VoD services to different type of devices. and proposed a new conceptual model whereby a MANET node is possible to move through heterogeneous networks and infrastructures, there are also several nodes connected and receiving VOD services in different communication and infrastructural approach also we proposed for our system architecture Global Media Forwarder to provides wide area services through deployed infrastructures such as 3G and WIMAX as well as a new protocol call (DNDS) will be used for accumulating the required information from the MANET nodes and Media Forwarders for configuring and providing optimal services to the MANETs users, implemented and executed between Media Forwarders, CVSP and the MANETs nodes.

In this paper we present a digital beamforming scheme for wireless communication systems based on high altitude platforms. The proposed digital beamforming scheme, which is installed on the platforms in high-altitude-platform (HAP) systems, can reduce significantly the number of antenna elements and the corresponding receiver modules, analog to digital (A/D) converters etc. without loss of performance. As a result, the system complexity and the system costs can be reduced, therefore enhancing feasibility of HAP-based systems. Moreover, in the proposed scheme, it allows to specify narrow main beam width and low sidelobe level simultaneously. An illustrative example, which demonstrates the design of the new method, is included

Focusing on characterizing fully symmetric four-port devices using a two-port vector network analyzer (VNA), the authors formulate a new method of measurement in this paper. The device under test (DUT), is embedded in two probe pads and two auxiliary terminations for one to perform on-board measurement using two ground-signal-ground (GSG) probes and a two-port VNA. The DUT is a 30 GHz substrate integrated waveguide (SIW) Riblet short-slot hybrid with microstrip-to-waveguide transitions, and is fabricated on Rogers RO4003 reg substrate with 8 mil thickness. By taking advantage of the thru-reflection-line (TRL) calibration technique and the new method, the four-port scattering matrix (S-matrix) of DUT is reconstructed.

In this work we present an accurate and cost-effective system for measuring S-band signal attenuation due to rainfall. The system is based on a pair of transmitter and receiver, operating at the lower limit of S-band, i.e. 2 GHz, separated at few meters distance and thus at any instant the rain's strength is uniform at this short path. The system is installed in two adjacent buildings inside University of Ioannina campus and at very close distance from the university's meteorological station. We present system's measurement modules as well as operating parameters. Finally, we present preliminary rain measurements for moderate, heavy, very heavy and extreme precipitation rates. Significant results, concerning correlation of the four precipitation rate cases with signal attenuation, are obtained.

A model that is less sensitive to errors in the extreme small and large drop diameters, the gamma model with central moments (3, 4 and 6), is proposed to model the rain drop size distribution of Singapore. This is because, the rain rate estimated using measured drop size distribution shows that the contributions of lower drop diameters are small as compared to the central drop diameters. This is expected since the sensitivity of the Joss distrometer degrades for small drop diameters. The lower drop diameters are therefore removed from the drop size data and the gamma model is redesigned for its moments. The effects of the removal of a particular rain drop size diameter on the specific rain attenuation (in dB) and the slant-path rain attenuation calculations with forward scattering coefficients for vertical polarization are analyzed at Ku-band, Ka-band and Q-band frequencies. It is concluded that the sensitivity of the Joss distrometer although affects the rain rate estimation at low rain rates, does not affect the slant path rain attenuation on microwave links. Therefore, the small drop diameters can be ignored completely for slant path rain attenuation calculations in the tropical region of Singapore.

Ultra-wideband (UWB) has potential applications in variety of medical areas such as implant wireless sensors, microwave hyperthermia, imaging and radar. The wave propagation inside human body must be known for an efficient system design for the different applications. In ...

Abstract An introduction to the use of real time data acquisition and analysis in meteorological applications is given, with examples of areas in which such techniques are becoming important. A detailed description is given of a readout system being constructed for a disdrometer (raindrop measuring gauge) using a VLSI neural network chip. Tests on simulated data give promising results down to droplet diameters of 0.05 mm, about a factor of 10 lower than what has been possible with previous methods

An introduction to the use of real time data acquisition and analysis in meteorological applications is given, with examples of areas in which such techniques are becoming important. A detailed description is given of a readout system being constructed for a disdrometer (raindrop measuring gauge) using a VLSI neural network chip. Tests on simulated data give promising results down to droplet diameters of 0.05 mm, about a factor of 10 lower than what has been possible with previous methods

The spectral capacity of VHF aeronautical radio is rapidly reaching saturation in the United States and in Europe. A key functional objective for any future civil aviation communications technology is providing relief to the current spectral congestion. This article provides a review on the existing national and global aeronautical radio networks. The spectrum depletion problem is described. Recent developments in narrowband and wideband digital communications for potential applications in civil aviation are discussed. Comments are made on critical issues that must be considered when selecting a communication technology for aeronautics which addresses the spectral congestion problem and simultaneously supports transformation to a long term network centric solution. Recommendations are made on some possible communication technologies that may bring about short-term resolution to VHF spectrum depletion without requiring major changes in ground infrastructure or on-board avionics.

... Misrod (13 km) Manideep (23 km) ... The mechanical properties of the reed set the frequency of operation, which is typically a few kilohertz. The high voltage trans-former sends current through the primary winding Lp of the high-Q RF transformer into the mica plate capacitor Cp. ...

We propose a simple and rigorous procedure for the full-wave analysis of folded filters and diplexers. By following this procedure, and assuming the availability of a code producing the Generalized Scattering Matrix (GSM) of the step discontinuity, it is shown that, in many cases, it is possible to analyze folded filters and diplexers, avoiding the development of specific routines for bends and T-junctions modelling. The analysis of the entire structure is obtained by simple matrix manipulations of the GSM and by a suitable partitioning of the device. Numerical examples validate the proposed approach.

An original and general method is proposed to predict the impact of electromagnetic effects due to the environment on the error performance of microwave communications systems. The method is based on the concept of a processoriented model which consists of a simplified representation of the physical phenomenon responsible for transmission impairments and simulates its influence on the signals received by any given communications link. The method yields a thorough characterization of the system impairments in both the time domain, by calculating the fluctuations of the received signal during the evolution of the physical process, and the frequency domain, by inferring the communication channel transfer function from the frequency dependence of the received waveform. In addition, by introducing the simulated channel transfer function as a filter in a communications system simulation software, the method evaluates the degradation induced on system performances. Three applications as different as scintillation due to turbulence in clouds, depolarization by rain and ice crystals, and interference in the presence of diffraction on obstacles demonstrate the ability of the method to deal with actual radio-communications system impairments.

A phase conjugation based method f o r full-duplex digital communications is discussed. The method uses a spatially confined and directive antenna pattern while a fullduplex digital communications link is maintained between moving platforms. The communications ability of the array is based on processing the phase associated with the message and the phase associated with the platform's motion separately. Preliminary measurements at 6 GHz indicate that the phase conjugation method does allow simulatous tracking and communications. 0-7803-4506-1/98/$10.00 0 1998 IEEE.