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Antennas Extend Wireless Systems

June 15, 2011
Newer antenna designs are achieving smaller footprints and, at the same time, broader bandwidths, as more and more antennas are asked to handle multiple frequency bands.

Antennas are often taken for granted in a system design. While they lack the elegance of components like amplifiers and data converters, they are just as vital to the success of a communications, radar, electronic-warfare (EW), or other electronic system. With more electronic systems reaching for higher levels of modulation to squeeze more data into a transmission, antenna designers are seeking even more efficiency than ever before.

A current trend in the packaging of electronic systems is the integration of more functions within smaller housings. Tactical radios, even cellular telephones, are including additional capabilities such as Global Positioning System (GPS) receivers. In support of such multifunction systems, Pulse Electronics Corp. developed an ultrathin active GPS antenna that also supports third-generation (3G) cellular systems, such as GPRS, GSM, UMTS, and WCDMA. The model W4150GG5000 antenna (Fig. 1) can be installed with either side facing up so only one antenna per housing is required, whether mounting on a windshield or dashboard of a vehicle. the antenna receives location information from a GPS satellite and uses the cellular network to transfer this data to a central control center or third party. The antenna assists in vehicle and asset tracking and location, navigation, and emergency call systems. It measures 100 x 50 mm with a height of only 8 mm.

The antenna functions over 3G frequencies of 824 to 960 MHz with 2-dBi gain and 1710 to 2170 MHz with 4-dBi gain and as much as 70% radiated efficiency. for GPS, it operates at 1575.42 MHz with maximum gain of 26 dBi. Beatrice Colbeau, Product Manager for Pulse Wireless' Device Division, comments on the antenna's flexibility: "The W4150 series delivers high performance functionality integrated into an ultra-slim elliptical package which provides an aesthetically pleasing addition. It can be installed with either side facing up, making it an extremely flexible solution for the windscreen or dashboard of any vehicle."

Antenna design expertise at Kaltman Creations LLC extends very low in frequency, as the firm's customers have often asked for lower-frequency antennas for such measurement applications as electromagnetic-compatibility (EMC) testing. As a result, the company recently announced new lines of extremely low frequency (ELF), super-low-frequency (SLF), and low-frequency (LF) measurement antennas. These antennas expand on the firm's higher-frequency radial isotropic and log-periodic antennas for EM compliance testing, spectrum surveys, and general research applications.

The new antennas provide frequency coverage from 3 Hz to 60 MHz (across six models). The antennas carry the company's "LoWavz Antennas" trademark and provide flat gain in both directional and omnidirectional radiation patterns (Fig. 2). according to Mark Kaltman, President of Kaltman Creations, "We have a strong customer base in the 1 Hz to 1 MHz and 1 MHz to 9.4 GHz ranges as a result of our spectrum analyzer sales. Our new LoWavz antenna line fills the need for affordable yet accurate low frequency applications covering the ELF to HF bands." Most of the lightweight antennas are designed for 50-Ω systems and provide as much as 12 dBi gain. Several models include external preamplifiers for additional signal boosts.

CommScope loaned its antenna design expertise to the development of improved public safety communications networks. Earlier this year, the firm supplied numerous wireless products from its Andrew Solutions lineup to enable operation of the Department of Commerce's Public Safety Communications Research (PSCR) Demonstration Network in Boulder, CO. the firm's base-station antennas are currently the only antennas in use at the demonstration network sites. "The PSCR Demo Network was designed to create a totally interoperable, broadband public safety network across the US, and we are proud to be contributing the RF Path antennas and cables that are making it possible," says Paul Bell, Senior Vice-President and General Manager for Base Station Antenna and Microwave Products at CommScope.

The PSCR Demo Network allows police, fire, and emergency services professionals to test equipment for interoperability on the 700-MHz fourth-generation (4G) Long Term Evolution (LTE) cellular communications band. It is a joint effort between two Department of Commerce agencies, the National Institute of Standards and Technology and the National Telecommunications and Information Association. The network consists of three sites on which various stakeholders and end-users can test the interoperability of their equipment. The supplied equipment includes Teletilt base-station antennas with AISG 2.0 actuators, HELIAX transmission lines, connectors, and accessories, and antenna network management software.

An omnidirectional antenna model MD249 from Flann Microwave has been designed to provide a vertically polarized 360 field of view in its azimuth plane, with the widest possible acceptance angle in its elevation plane. It is optimized for use from 59 to 64 GHz, although it can operate from 50 to 70 GHz. Nominal gain is 1 to 3 dB. The design allows for tracking of sources above and below the horizontal plane; in addition, the antenna's characteristics can be used to maintain mobile communications over rough terrain. The antenna is supplied with a precision 1.85-mm coaxial connector, but can also be equipped with a waveguide feed if required. The omnidirectional antenna controls gain variations to 1.5 dB in the elevation plane and within 1.0 dB in the azimuth plane. The nominal half-angle 3-dB beamwidth is typically greater than 30 deg., while the nominal half-angle 10-dB beamwidth is typically greater than 60 deg. The maximum VSWR is 1.65:1. The antenna can handle as much as 5 W CW power.

Q-par Angus Ltd. recently announced an ultrawideband (UWB) omnidirectional antenna capable of covering from 1 to 40 GHz. Ideal for RF signal monitoring and surveillance as well as in test and measurement and electronic-warfare (EW) systems, the developmental antenna is expected to serve as a substitute for several existing antennas used for this frequency coverage. It yields as much as 5.5 dBi gain, with typically 1.5 dBi gain at 2 GHz. The antenna, with typical VSWR of 2.3:1, can handle power levels to 20 W CW. It measures just 100 mm in diameter by 90 mm high.

OC Series antennas from Antenna Factor are half-wave dipoles with higher gain than conventional whip antennas. Employing loaded-coil technology, these compact antennas minimize the length that would normally be needed for a given amount of gain at a given frequency. The antennas are available in 916- and 2400-MHz models and attach with a standard SMA or Part 15 compliant RP-SMA connector.

Finally, for antenna designers, software developers Computer Simulation Technology and EM Software & Systems-S.A. (Pty) Ltd. have announced the release of Version 3.0 of the Antenna Magus software. It includes 148 antenna topologies and 7 transitions, an expanded waveguide library, and a unique chart tracing tool to capture scanned graphs and images. In addition, users are now able to add their own custom antennas to the existing Antenna Magus database.

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