By Marcus C. Walden

Abstract: This paper presents the antenna G/T degradation incurred when communications systems use very inefficient receive antennas. This work is relevant when considering propagation predictions at HF (2-30 MHz), where it is commonly assumed that antennas are efficient/lossless and external noise dominates over internally generated noise at the receiver. Knowledge of the antenna G/T degradation enables correction of potentially optimistic HF predictions. Simple rules-of-thumb are provided to identify scenarios when receive signal-to-noise ratios might be degraded.

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By Marcus C. Walden

Abstract: This paper describes the design and characterization of a frequency-scanning meanderline antenna for operation at 60 GHz. The design incorporates SIW techniques and slot radiating elements. The amplitude profile across the antenna aperture has been weighted to reduce sidelobe levels, which makes the design attractive for radar applications. Measured performance agrees with simulations, and the achieved beam profile and sidelobe levels are better than previously documented frequency-scanning designs at V and W bands.

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Plextek presents two technical papers to the world’s leading experts on Antennas and Propagation at the IEEE International Symposium in July.

Cambridge, UK – 21st June 2017 – Design and innovation consultancy, Plextek will be presenting two technical papers at this year’s IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting in San Diego.

Widely recognised as a premier international forum, the world’s leading experts in antennas and propagation from academia, industry, and government will be there to discuss ideas on cutting-edge research and topics.

The week-long event will host a plethora of technical, education and social activities covering different specialist areas on antennas, propagation, electromagnetic engineering, and radio science.

Dr. Marcus Walden, Technical Lead in Antennas and Propagation commented:

“The Antennas and Propagation Symposium is a great forum to meet and network with people at the forefront of their technology areas, to exchange ideas and learn about cutting-edge topics. Antennas and propagation are integral to all radar and communications systems and, therefore, participation at events like this benefits the Plextek engineering design process. The knowledge gained from previous events has fed directly into Plextek system designs, including those for radar, smart-meter reading, and vehicle-telemetry amongst others. I’m really pleased to be able to present and share ideas with other industry thought leaders at such a prestigious event.”

The event will be held at the Manchester Grand Hyatt in San Diego, California and takes place from Sunday 9th of July to Friday 14th of July.

Dr. Marcus Walden will be delivering a 20 min presentation titled, “Antenna G/T Degradation with Inefficient Receive Antennas at HF (2-30 MHz)” as part of the session on Electronically Small Antenna Characteristics on Wednesday 12th of July.

Marcus will also participate in a two-hour interactive forum, where he will present his paper “A Frequency-Scanning Substrate-Integrated-Waveguide Meanderline Antenna for Radar Applications at 60 GHz” in the session on 60 GHz Radars and Communications on Thursday 13th of July.

For more information about our work on Antennas and Propagation, please visit our Antennas & Propagation page.

Notes to editors

Based near Cambridge, UK, Plextek designs new products, systems, and services for its clients in a diverse range of industries including defence & security, medical & healthcare, and wireless communications.

Central to its culture is the company’s ability to innovate, taking an idea from concept to market. For more than 25 years, our team of consultants, engineers and project managers has turned our clients’ business opportunities into commercial success, designing, manufacturing and supplying leading-edge products. Supported by our network of suppliers, commercial partners and research organisations, Plextek is the trusted partner of choice for more than 300 commercial clients, government agencies, and ambitious start-up companies.

For images, information or interview requests, please contact: Adam Roberts via email: press@plextek.com or call: 01799 533200

By Marcus C. Walden, Timothy Jackson & William Gibson

Abstract: This paper presents an initial empirical path-loss propagation model for communication links operating at streetlight/roof-top heights over the ranges of 100 m to 10 km in urban and suburban environments. The statistical path-loss model presented uses data taken from a significant number of deployed street-light telemetry systems transmitting in the licence-exempt/ ISM bands at 868 and 915 MHz. This propagation model provides a valuable tool for network planning where typical cellular propagation models might not be appropriate.

I. INTRODUCTION: Telensa Ltd. operate a network of street-light telemetry systems for a variety of customers (e.g. local and county councils) for control and monitoring of street lights. This capability is becoming desirable for energy efficiency and for service maintenance; for example, to switch off unnecessary lighting and/or to identify failing lights.

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By Marcus C. Walden

Abstract: This paper presents a comparison of Chilton ionosonde critical frequency measurements against vertical-incidence HF propagation predictions using ASAPS (Advanced Stand Alone Prediction System) and VOACAP (Voice of America Coverage Analysis Program). This analysis covers the time period from 1996 to 2010 (thereby covering solar cycle 23) and was carried out in the context of UK-centric near-vertical incidence skywave (NVIS) frequency predictions. Measured and predicted monthly median frequencies are compared, as are the upper and lower decile frequencies (10% and 90% respectively). The ASAPS basic MUF predictions generally agree with fxI (in lieu of fxF2) measurements, whereas those for VOACAP appear to be conservative for the Chilton ionosonde, particularly around solar maximum. Below ~4 MHz during winter nights around solar minimum, both ASAPS and VOACAP MUF predictions tend towards foF2, which is contrary to their underlying theory and requires further investigation. While VOACAP has greater errors at solar maximum, those for ASAPS increase at low or negative T-index values. Finally, VOACAP errors might be large when T-SSN exceeds ~15.

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