High Performance, Low-Cost, Multiband Antenna Arrays with Beam Steering Capabilities for Wireless Communication Systems

Our group has several novel antenna design projects with the following objectives:

  1. Develop broad- and multi-band antennas and antenna arrays for hand held wireless communication devices
  2. Develop high performance, low-cost phased arrays with beam steering capabilities.

For the low cost multi-band antennas and antenna array, design approach is based our patented technology (US patent # 6,201,509, and US patent # 7,079,082) and using the continuous transverse stub (CTS) antenna technology [21, 22]. The developed designs have the advantage of low-cost, good impedance matching, multi-band using a single feed, and good tolerance to manufacturing errors. Fig.1 shows prototypes of a three elements single band array operating in the X-Band, and a photograph of a fabricated six elements multi band coaxial CTS array operating at both 4.2 GHz (c-band), and 19.4 GHz K-band) [22]. The design process is based on extensive simulation effort using a multi-grid Finite-Difference Time-Domain code also developed by our group [23]. Through research funding from the Army Research Office (ARO) we continue to develop new versions of these CTS deigns including the use of Electromagnetic Band Gap (PBG) perfect magnetic conducting planes to reduce the antenna size in half while maintaining its uniform radiation pattern in half space [3].

In another project funded by the Office of Naval Research (ONR) our group is using the coplanar waveguide CTS (US patent # 7,079, 082) and Ferroelectric materials technologies to develop low cost antenna array with beam steering capabilities [24]. Fig. 2a shows an example of a two elements coplanar waveguide CTS antenna array with Ferroelectric materials layers between the radiating stubs. Fig. 2b, shows resulting radiation patterns with and without biasing the Ferroelectric layer. The result shown in Fig.2b clearly illustrates the beam steering capability of this approach.

Fig. 1. (a) Photograph of fabricated multiband six-element coaxial CTS antenna array designed to operate at 4.2 and 19.4 GHz. (b) Comparison of measured (+s) and simulated (solid) radiation pattern at 4.2 GHz for the six element multiband coaxial CTS antenna array.

It should be noted that our group has developed a technique to overcome this difficulty by implementing a multilayer dielectric materials (SiO2 or polymer) as a middle layer between the tunable Ferroelectric material and the metallization [2]. On going efforts in this project are related to the fabrication of these multilayer integrated phased array antennas and validating the simulation results experimentally. With the recent expansion of the research facilities at HCAC, the group has now acquired a sputtering chamber for the multilayer development of the phase shifters (including the Ferroelectric and SiO2 layers) and also a microprobe station for testing the developed devices.

Fig. 2. (a) Simulation model of the integrated CTS phased array antenna and Ferroelectric phase shifter, (b) Simulation results illustrating the beam scanning capability using this low cost integrated technology [2].

Tasks and deliverables

  1. Develop prototypes of the integrated Ferroelectric and coplanar CTS phased array antenna design using the multilayer approach to reduce insertion losses while maintaining a high figure of merit.
  2. Examine the effectiveness of the proposed voltage biasing approach and determine the span of the beam steering capabilities while maintaining biasing in the 20 Volts range

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