2nd IET Annual Active and Passive RF Devices Seminar
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- Location: Birmingham, UK
- Conference date: 29 Oct. 2014
- ISBN: 978-1-84919-972-8
- Conference number: 2014/002
- The following topics are dealt with: passive RF devices; antenna radiation pattern characterisation; G-band planar Yagi antennas; dual-band WLAN antenna array; harmonic suppression; millimeter wave gyro-devices; cusp electron gun; submillimetre wave Fabry-Perot cavity antenna; piezoelectric actuators; W-band quasi-optical mode converters; rectangular microstrip patch antenna; envelope tracking transmitters and W-band gyro-TWA.
7 items found
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Radiation pattern characterisation setup for G-band planar Yagi antennas
- Author(s): K.H. Alharbi ; A. Ofiare ; J. Wang ; A. Khalid ; D. Cumming ; E. Wasige
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On-wafer radiation pattern characterisation test structure for G-band planar Yagi antennas is presented in this paper. It employs a number of identical planar Yagi antennas (one as a receiver and surrounded by multi transmitters) fabricated on the same substrate. On-wafer measurements are done using a Vector Network Analyser (VNA) to measure the radiation intensity at the different receiver-transmitter antenna configurations. Measured and simulated radiation patterns are in a good agreement. The designed planar Yagi antenna shows very wide bandwidth (S11< -10 dB) over the whole G-band. Higher front-to-back ratio could be obtained through optimised reflector geometry.
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Dual-band WLAN Antenna Array with Integrated Filters for Harmonic Suppression
- Author(s): W. Ahmad and D. Budimir
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This paper presents the design, modelling and results of a dual-band antenna array integrated with filters. The array is fed via a single 50 Ω port and consists of two radiating elements. Hence, a 1×2 array structure. The two bands of the antenna array correspond to the two WLAN bands of 2.4 GHz and 5.8 GHz. Other than the two fundamental resonant frequencies, the standalone array has spurious harmonics at various other frequencies. For the suppression of these harmonics, the array is integrated with two bandpass filters, centered at 2.4 GHz and 5.8 GHz. The antenna array with integrated filters was electromagnetically modelled and the simulation results have been presented. The acquired results are considerably acceptable; showing the array to have dual-bands at 2.4 GHz and 5.8 GHz, at a return loss of more than 20 dB, and also successful suppression of the spurious harmonics of the antenna array.
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Optimization of a Cusp Electron Gun for Millimeter Wave Gyro-Devices
- Author(s): C.R. Donaldson ; L. Zhang ; A.W. Cross ; A.D.R. Phelps ; K. Ronald ; W. He
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A thermionic cusp electron gun has been designed, numerically optimized and experimentally measured and is presented. A 40 kV, 1.5 A annular axis-encircling electron beam has been simulated to generate a beam with low velocity and alpha spreads. The electron gun performance has been verified through experiments. Based on the measured results further improvement and optimization of the cusp gun for high frequency operation were carried out and the results will be presented.
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W-Band Quasi-Optical Mode Converters for Gyro-Devices
- Author(s): P. McElhinney ; C.R. Donaldson ; I. Zhang ; A.W. Cross ; W. He
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A W-band corrugated horn has been designed, manufactured, and experimentally measured at the University of Strathclyde, for integration into a gyro-device as a quasi-optical launcher. This horn converts a cylindrical TE11 mode into a free space TEM00 mode in a frequency band of 84-104 GHz with a reflection better than -30 dB and a Gaussian coupling efficiency of ~98% and directivity of 26.6 dB at 95 GHz. The Gaussian output of the horn and small beam waist makes such a horn ideal for integration with applications and for use with a depressed collector system. The measured results are in excellent agreement with the numerical simulations.
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Simple methods for enhancing bandwidth of a rectangular microstrip patch antenna
- Author(s): M.S. Rabbani and H. Ghafouri-Shiraz
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In this paper we have introduced two methods namely (i) taper matching and (ii) quarter wavelength width extension to increase the bandwidth (BW) of a rectangular microstrip patch antenna (RMPA). Also we have studied the effect of applying both methods on the antenna performance. Simulation and experimental results on a 5 GHz patch antenna using these methods have been presented.
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Impact of Envelope Shaping on the Linearity of Envelope Tracking Transmitters
- Author(s): G.T. Watkins and K. Mimis
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A simulator is described for evaluating the impact of timing misalignment between the envelope and RF paths in an envelope tracking (ET) transmitter. Impact is measured by the degradation of the output adjacent channel power ratio (ACPR) when amplifying a 5MHz bandwidth 3GPP Long Term Evolution (LTE) signal. This is modelled with an ideal power amplifier (PA) which has no drain voltage gain dependency. Envelope shaping (ES) is applied and shown to increase the tolerance to timing misalignment, indicating that the nulls of the envelope signal are more susceptible to misalignment than the peaks. Finally measurements from a practical modulator are integrated into the simulator and its impact on ACPR evaluated.
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Design and tests of a W-band gyro-TWA and its components
- Author(s): L. Zhang ; W. He ; C.R. Donaldson ; P. McElhinney ; K. Ronald ; A.D.R. Phelps ; A.W. Cross
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A W-band gyrotron traveling wave amplifier (gyro-TWA) with helically corrugated waveguide and cusp electron gun is presented. The beam-wave interaction, based on the cyclotron resonance maser instability, is driven by a 40 keV, 1.5 A axis-encircling electron beam generated by the cusp electron gun. Numerical simulations predict a maximum output of 5-10 kW with a 3 dB frequency bandwidth of 90-100 GHz and a saturated gain of 40 dB. Linear analysis and numerical simulation of the performance characteristics of the amplifier and its millimetre wave components will be presented as well as the latest experimental measurements.
