In part I of this paper, we presented the basic architectures and theory for passive and active phased arrays. Here, we review array implementation, state-of-the-art applications, and identify future trends in phased-array technology.

Phased arrays-part II: implementations, applications, and future trends

A compact phase shifter using reconfigurable defected microstrip structure (RDMS) is proposed for phased array antennas. A complete phase shifter design scheme that serves as an engineering guidance is described. Stepwise phase shifters that have phase-shifting ranges of 90° and 180° with a step size of 45° are designed, fabricated, and tested. The experimental results demonstrate that the size, maximum insertion loss of the phase shifters, and the quantity of the lumped elements are reduced by 80%–90%, 25%–30%, and 50%, respectively, compared to our previous work. Subsequently, a four-element phased array is built employing such RDMS-based phase shifters, realizing a size reduction of 55% in the array size. The measurement results show that the phased array antenna is able to switch its main beam between $-15^\circ$ , 0°, and 15° in the H-plane, with the average realized gain around 10 dBi.

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A Compact Microstrip Phase Shifter Employing Reconfigurable Defected Microstrip Structure (RDMS) for Phased Array Antennas

Radio frequency identification (RFID) systems have many important applications in the 900 MHz frequency band. A 3x2-element planar smart antenna for RFID readers in a low cost compact package is developed. The smart antenna covers 860-960 MHz frequency band with more than 10 dB input return loss, 12 dBi broadside gain and up to 40deg elevation beam scanning with a 4-bit reflection type phase shifter array. Once implemented in the mass market, RFID smart antennas will contribute tremendously in the areas of RFID tag reading rates, collision mitigation, location finding of items and capacity improvement of the RFID system.

Development of Smart Antenna for RFID Reader

In this paper the design of an X-band frequency reconfigurable patch antenna has been demonstrated using PIN diode. A square slot has been introduced in order to realize PIN diode effect in antenna parameters. The tuning of frequency is realized by changing its effective electrical length, which is controlled by different mode of the PIN diode by applying different bias voltages across it along the slot of the antenna. An annular slot rectangular patch antenna is used and a gap of 2mm is used to attach PIN diode. When the PIN diode is forward biased i.e gap is closed by PIN diode and current will flow along the outer ring. ±60 MHz (1.34 %) tuning of frequency has been obtained by applying the bias voltage of 3 volt. The structure has been simulated in ADS software. Simulated and measured performances are presented. Results are used to demonstrate that there is good agreement between the simulated and measured results. The match between simulation and measured results suggests that proposed candidate can be used as a frequency reconfigurable antenna.

Frequency reconfigurable patch antenna using PIN diode at X-band

A switchable substrate integrated waveguide is presented that can be switched between two different modes of propagation via the biasing of a pin diode switch. To demonstrate the usefulness of the design a single pole single through (SPST) waveguide switch is presented. The switch is shown to have approximately 50 dB isolation and 3 dB insertion loss over the switchable bandwidth.

Robert V. Garver

Papers

Microwave Diode Control Devices