Antennas and Propagation

The Antenna Group is a research and development team spanning all aspects of antennas.  Services include inventing new antennas; developing application-specific antennas; performing studies on antennas and communication systems; and measurements for characterization of antennas.  Applications include sophisticated, high-performance government antenna systems and low-cost wireless antennas.  The Antenna Group includes the Satellite Communications Group and is a part of the Center for Wireless Telecommunications.

Need for Research

The success of any wireless communications device is integrally tied to the antennas used to transmit the signal. The antenna design must not only meet the technical requirements for propagating the signal but must also conform to aesthetic and form factor requirements. The statistical nature of electromagnetic wave propagation combined with a myriad of environmental elements, such as multipath, path loss, reflection, and scattering makes antenna design and propagation research an art as well as a science.

Technical Approach

The Antenna Group is a research and development team spanning all aspects of antennas. Services include inventing new antennas; developing application-specific antennas; performing studies on antennas and communication systems; and measurements for characterization of antennas. Applications include sophisticated, high-performance government antenna systems and low-cost wireless antennas. Utilizing state of the art measurement and analysis facilities, such as our anechoic chamber, we can design and test new systems limited only by our imagination. We are training the next generation of antenna and propagation leaders for the industry, government and academia.

VTAG personnel in the Anechoic Chamber

Services

Design
The Antenna Group designs a variety of antennas including low-profile, microstrip, wire and reflector antennas. It has a variety of design aids, including both commercial software packages and in-house custom codes.

Measurements
The Antenna Group designs and measures a variety of antennas and antenna systems. The Group has an outdoor antenna range for measuring antennas up to 40 GHz. An indoor anechoic chamber with both near field and far field measurement capability from 900 MHz to 40 GHz was installed recently. Two network analyzers are available for impedance measurements.

Fabrication
Printed antennas are fabricated and tested on site. This includes simple patch antennas and complex wideband elements and arrays. Other types of antennas, such as wire antennas, are also constructed.

Studies
We are especially interested in performing full research studies. Sponsor requirements are used to guide tradeoff studies that lead to proof-of-concept demonstration test articles, followed by refinement phases. Many computer codes are available for design studies.

Current Research Areas

Smart Handheld Antennas
Extensive measurements and modeling have are being performed for handheld transceivers with multiple antennas for diversity and adaptive beamforming. Measurements at many sites show that spatial, polarization, and pattern diversity all provide significant diversity gain. Interference rejection of 20 to 40 dB has been demonstrated using adaptive beamforming.

Smart Base Station Antenna Systems
Smart base station antenna systems operating in the cellular and PCS bands are being used for experiments with three diversity schemes: spatial, polarization, and angle. The performance of these three base station diversities are being compared under typical mobile user conditions.

Antennas for Personal Communications
Small antennas are designed and constructed for use with handheld devices and other applications at cellular frequencies and above.

Wideband Antennas
A number of printed circuit antennas have been designed and constructed for use above 1 GHz with bandwidths of 50% up to 10:1. Linear, circular, and dual polarized antennas are possible.

Wideband Arrays
To meet the demand for wideband multifunctional arrays, we are investigating several array architectures for very wideband applications. Antennas for Unlicensed Bands and Other Applications A stub loaded helix antenna for use with terminals in unlicensed band applications has been patented. It occupies less than 30% of the volume of a conventional helix antenna. It has been extensively tested and commercial units at 2.4 GHz are being manufactured. The SLH antenna is used primarily as an access point antenna. Smaller antennas are being developed for terminals.