Topic
Active antenna
About: Active antenna is a research topic. Over the lifetime, 2246 publications have been published within this topic receiving 26493 citations.
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TL;DR: In this article, a 10 GHz hybrid Y-Ba-Cu-O/GaAs microwave oscillator proximity coupled to a circular microstrip antenna has been designed, fabricated, and characterized.
Abstract: A 10-GHz hybrid Y-Ba-Cu-O/GaAs microwave oscillator proximity coupled to a circular microstrip antenna has been designed, fabricated, and characterized. The oscillator was a reflection mode type using a GaAs MESFET as the active element. The feedline, transmission lines, RF chokes, and bias lines were all fabricated from YBa/sub 2/Cu/sub 3/O/sub 7-x/ superconducting thin films on a 1-cm*1-cm lanthanum aluminate substrate. The output feedline of the oscillator was wire bonded to a superconducting feedline on a second 1 cm*1 cm lanthanum aluminate substrate, which was in turn proximity coupled to a circular microstrip patch antenna. Antenna patterns from this active patch antenna and the performance of the oscillator measured at 77 K are reported. The oscillator had a maximum output power of 11.5 dBm at 77 K, which corresponded to an efficiency of 10%. In addition, the efficiency of the microstrip patch antenna together with its high temperature superconducting feedline was measured from 85 K to 30 K and was found to be 71% at 77 K, increasing to a maximum of 87.4% at 30 K. >
6 citations
01 Apr 2009
TL;DR: In this paper, an analysis of a Gunn loaded patch with parasitic elements at radiating edges of the patch has been carried out using equivalent circuit concept for different values of bias voltage and threshold voltage.
Abstract: An analysis of Gunn loaded patch with parasitic elements at radiating edges of the patch has been carried out using equivalent circuit concept for different values of bias voltage and threshold voltage. It is observed that addition of parasitic elements improves the band of operation to 400 MHz (bandwidth 4.48%, center frequency 8.95 GHz) as compared to 297 MHz (bandwidth 3.06%, center frequency 8.90 GHz) for Gunn loaded patch. Antenna also shows tunability of 50 MHz for bias voltage from 8 to 15 V for a given threshold voltage of 4.4 V and exhibits enhanced radiation by 0.5833 dB as compared to patch alone. Various parameters of the antenna are compared with simulated data using IE3D.
6 citations
Patent•
16 Dec 2015
TL;DR: In this article, the authors proposed a method for detecting a receiving end in a generalized spatial modulation communication system, which consists of the following steps that: after passing through a channel, a signal transmitted by a transmitting end of the GSM communication system enters an antenna pair mapping detector to process; the received signal entered a constellation diagram mapping detector after being processed by the antenna-pair mapping detector.
Abstract: The invention discloses a method for detecting a receiving end in a generalized spatial modulation communication system. The method comprises the following steps that: after passing through a channel, a signal transmitted by a transmitting end of the generalized spatial modulation communication system enters an antenna pair mapping detector to process; the received signal enters a constellation diagram mapping detector to process after being processed by the antenna pair mapping detector; the distance between a constellation diagram mapping signal and a constellation mapping point is calculated in the constellation diagram mapping detector for the first time; then, matrix operation is carried out; Euclidean distances are added; finally, a constellation mapping sending symbol is obtained; and simultaneously, the numbers of active antenna pairs are obtained while the active antenna pairs pass through the antenna pair mapping detector. The method disclosed by the invention has the advantages that: compared with the linear detection algorithm, the algorithm complexity is nearly not increased; furthermore, better error rate performances can be provided; compromise of the error rate performances and the algorithm complexity is achieved; simultaneously, in the aspect of constellation diagram demapping, a soft distance decoding manner, instead of a hard decoding manner, is utilized; and thus, the error rate is further decreased.
6 citations
TL;DR: A comparison of performance of simple stochastic cellular learning automata (SCLA) technique with only one input to comparatively complex Q-learning technique with two or more inputs reveals that increasing complexity of learning process does not necessarily benefit the system performance.
Abstract: Active antenna systems in 4G and upcoming 5G networks offer the ability to electronically steer an antenna beam in any desired direction. This unique feature makes them a suitable candidate for realizing self organizing network (SON) architectures in 5G for optimizing of key performance indicators like throughput, file transfer time etc. In this paper, we aim to analyse the effect of increasing number of input variables and complexity of learning techniques on the performance of the network. We compare performance of simple stochastic cellular learning automata (SCLA) technique with only one input to comparatively complex Q-learning technique with two or more inputs. We use FTP flow based 5G network simulator for our work. The SON architecture model proposed, is distributed with optional inter cell communication. Simulation results reveal that increasing complexity of learning process does not necessarily benefit the system performance. The simple SCLA technique shows more robust performance compared to Q-learning case. However, within the same technique increasing the number of input variables does benefit the system, indicating that a complex technique can ultimately prove beneficial in complicated scenarios provided it is able to quickly process and adapt to the environment.
6 citations
TL;DR: Field trials to evaluate downlink (DL) multi-user (MU)-MIMO performance by using a prototype low-SHF-band centralized-RAN Massive MIMO system indicate that the total DL system throughput and user data rate can be significantly improved.
Abstract: Massive multiple input and multiple output (Massive MIMO) is a key technique to achieve high system capacity and user data rate for the fifth generation (5G) radio access network (RAN). To implement Massive MIMO in 5G, how much Massive MIMO meets our expectation with various user equipment (UEs) in different environments should be carefully addressed. We focused on using Massive MIMO in the low super-high-frequency (SHF) band, which is expected to be used for 5G commercial bands relatively soon. We previously developed a prototype low-SHF-band centralized-RAN Massive MIMO system that has a flexible active antenna system (AAS)-unit configuration and facilitates advanced radio coordination features, such as coordinated beamforming (CB) coordinated multi-point (CoMP). In this study, we conduct field trials to evaluate downlink (DL) multi-user (MU)-MIMO performance by using our prototype system in outdoor and indoor environments. The results indicate that about 96% of the maximum total DL system throughput can be achieved with 1 AAS unit outdoors and 2 AAS units indoors. We also investigate channel capacity based on the real propagation channel estimation data measured by the prototype system. Compared with without-CB mode, the channel capacity of with-CB mode increases by a maximum of 80% and 104%, respectively, when the location of UEs are randomly selected in the outdoor and indoor environments. Furthermore, the results from the field trial of with-CB mode with eight UEs indicate that the total DL system throughput and user data rate can be significantly improved. key words: 5G, Massive MIMO, low-SHF-band, MU-MIMO, beamforming, C-RAN, CB, CoMP
6 citations