Rev 1.32 Pub–Sep 2009 – Author NJ Smith nsmith@rfsavvy.com ©2009 RF Savvy LLC - All Rights Reserved www.rfsavvy.com

WIRELYSS™ Embedded Antenna Technology Enabling The Green-Tech SMART Meter Revolution

By Norman Smith

Traditional, so called, under the glass mount

antenna technologies and other custom developed flex-circuit board antenna solutions that are frequently mounted with double sided tape, are not considered long-term reliable methods for locating antennas in electric utility meters. Also as the rate of Wireless integration increases space becomes a burden to design engineers working to integrate the systems under the meter cover. For instance utility meter collector units, are configured with two or more radio communication systems for wireless access to the internet as well as peer to peer communications within the mesh network. These systems are used for short range Home Area Network (HAN) communications, Wide Area Network (WAN) public cellular communications, intermediate ISM band communications and even GPS location based systems all of which are necessary in today’s advanced SMART Utility Meter deployments. Space Constraints The many antennas necessary for these communication systems are forced to compete for prime position or real estate on the utility meter body. This trend, of ever increasing embedded wireless requirements, is similar to that seen in the consumer wireless mobile phone market in recent years and is forcing antenna designers to compromise meter communications system performance as available real-estate becomes a challenge. What is needed is a means of leveraging available real estate on the solid state utility meter cover, see example in fig 1.0 above.

Solid state utility meter dielectric covers currently house no electronics, but have the potential to offer a perfect dielectric medium for mounting one or more antennas. Of course any meter cover mounted antenna solution would have to allow easy access for serviceability of the meter, therefore a permanently attached antenna with coaxial cable would be unacceptable. Meter Cover Un-tethered Embedded Antenna A recent technical study conducted by RF Savvy® has resulted in a patent-pending approach for WIRELYSS™ embedded antenna technology that enables designers to create multiple un-tethered antennas embedded or located within the utility meter cover itself. Fig 2.0 shows an example un-tethered dipole antenna designed to operate at 850MHz and fabricated on the inner surface of the meter cover. Note the absence of any radio frequency coaxial cable. The signal and ground connections are simply made between the cover mounted antenna and the radio modem mounted inside the meter body via capacitive or inductively coupled (spring loaded) electrodes that are attached to the meter body, the coaxial cable then connects from the meter body electrodes to the radio modem.

There are reckoned to be over 2 billion utility meters world-wide, with only about 10% of those capable of remote meter reading. The recent global economic downturn has spurred the passing of US government green-technology stimulus packages, to the tune of billions of dollars, with massive rebates available to utilities installing Automated Metering Infrastructure (AMI) and SMART Meters

(1). China, Europe and other

countries are also pledging similar infrastructure investments. Present commercial-off-the-shelf electric utility meter embedded antenna solutions offer inferior and unacceptable price-performance benefits as deployment run-rates push through the 100,000 units/month mark. As price-pressure increases on antenna designers, there exists a pressing need for cost-effective embedded antennas with break-through price-performance benefits.

(1) – American Recovery Reinvestment Act (ARRA) Feb 17th 2009 http://www.recovery.gov/

Fig 1.0 Example Solid State Electric Utility Meter

Fig 2.0 Un-tethered 850MHz dipole antenna example

Rev 1.32 Pub–Sep 2009 – Author NJ Smith nsmith@rfsavvy.com ©2009 RF Savvy LLC - All Rights Reserved www.rfsavvy.com

ABOUT THE AUTHOR: Norman Smith is Founder and CEO of RF Savvy® LLC an independent wireless design house that is focused on innovating green-tech antennas for next generation SMART Meters. He is a creative entrepreneur and successful businessman with over 20 years experience in the Wireless industry for companies that include; Nokia, GEC-Marconi, Hewlett Packard, Agilent Technologies and WP Wireless. Norman obtained his Bachelors degree in Electrical and Electronics Engineering from the University of Hertfordshire (England) and also holds an OND and HNC in Electronics and Telecommunications. He has spent the last 5 years successfully innovating embedded antennas for electric utility meters that have been used in; Landis & Gyr, Itron, Elster Electric and other automated meter reader solutions. RF Savvy® LLC (www.rfsavvy.com) is headquartered in California, USA. Norman can be reached at nsmith@rfsavvy.com For news/updates follow us at www.twitter.com/rfsavvy

Conclusions When compared with commercially available under-glass-mount or flexible printed circuit discrete antenna costs, the methods presented in this paper, of embedding antennas into the meter cover, are expected to be in the order 50% to 75% less per antenna. This will be an important factor in minimizing BOM costs for residential AMI SMART meters which themselves will need to be at USD $50 or less per meter to accommodate the massive ramp-up that the aforementioned stimulus packages and industry growth necessitates. Meanwhile meter manufacturers can expect to have an easier time passing FCC, and wireless carrier certifications such as PTCRB, due to the improved antenna mounting locations that this un-tethered antenna technology offers.

Commercial Manufacturing Techniques For mass production and optimum price/performance benefits the integral antenna elements, that may be fabricated from stamped metal or flex-printed circuit/film dielectric substrates, can be embedded into the meter cover plastic using a variety of commercially available manufacturing techniques including by way of example; insert-molding (one or two-shot processes), over-molding, molded-interconnect-device (MID), laser activated plastics such as LDS, or simply heat-staking the antenna elements to the inner surface of the meter cover. WIRELYSS™ Un-tethered Embedded Antenna Benefits This approach, of locating antenna elements integral to the meter cover itself, offers meter manufacturers significantly more real-estate to accommodate antenna elements. This method lends itself to a variety of antenna topologies that are possible including dipoles, monopoles, inverted F structures, slot antennas and even high dielectric resonator antenna structures. Furthermore the range of frequencies that can be supported by one or more antenna elements using this method include; 850/900/1800/1900/2.1GHz public cellular, ISM 2.4GHz, ISM 900MHz, Wi-Fi, Wi-Max and GPS bands. Additionally the radio frequency performance of the antenna (gain pattern/efficiency) is enhanced due to the increased distance away from the meter metrology circuits which have often been cited as a source of noise in some meter designs. Figures 3.0 and 4.0 show the measured VSWR and efficiency/gain pattern performance respectively of the example 850MHz WAN un-tethered antenna example from fig 2.0.

Fig 3.0 VSWR of Un-tethered dipole antenna example

Fig 4.0 Gain/efficiency pattern of Un-tethered dipole antenna example