A MEMS-based tunable coplanar patch antenna fabricated using PCB processing techniques

Abstract

In this paper, a tunable coplanar rectangular patch antenna (CPA) designed using a MEMS varactor is reported. The MEMS varactor is monolithically integrated with the antenna on Duroid substrate using printed circuit processing techniques. Specifically, the MEMS varactor located at one of the radiating edges capacitively loads the CPA. The resonant frequency of the antenna is tuned electrostatically by applying a DC bias voltage between the MEMS varactor and the actuation pad on the antenna. The movable MEMS varactor membrane deflects downward toward the actuation pad due to an electrostatic force of attraction caused by the applied DC bias voltage. The deflection of the varactor membrane decreases the air gap, thereby increasing the loading capacitance. The increase in the loading capacitance results in a downward shift in the resonant frequency of the CPA. The CPA is center fed at the second radiating edge using a 50 Ω CPW feed line. The CPA operates in the frequency range from 5.185 to 5.545 GHz corresponding to the down and up states of the varactor. The tunable frequency range is about 360 MHz and the return loss is better than 40 dB in the entire tuning range. In this tuning range, the required DC voltage is in the range of 0–116 V.

Design and Development of Millimeter-Wave Micromachined Patch Antennas

“…Recently, it has been shown that the behavior of CPA is almost similar to that of the conventional microstrippatch antenna (MPA) and it exhibits wider bandwidth and lower cross-polarization radiation as compared to MPAs [11]. Moreover, due to availability of both signal and ground lines on the same plane, frequency-tuning can be achieved by placing a PIN diode or a MEMS varactor across one of its radiating arms [12]. Till now, CPAs have been fabricated on low-permittivity substrates.…”

The Design and Modeling of a Reconfigurable Inset-Fed Microstrip Patch High Gain Antenna for Wireless Sensor Networks

“…By using MEMS switches, the parameters of an antenna can be controlled as desired. The tunable frequency range is about 360 MHz with the required DC voltage in range of 0 V-116 V or 0.8 to 15 percent of the nominal operating frequency [4][5]. These antennas tune their operating frequency based on the changing value of a MEMS varactor located at one of the radiating edges.…”

“…These antennas tune their operating frequency based on the changing value of a MEMS varactor located at one of the radiating edges. Therefore the tuning range can often be small [4][5]. Another type of antenna can be tuned between two significant frequencies owing to a change in the active geometry, turned ON or OFF using MEMS switches, has been presented in [6] and [7].…”

Design and Optimization of Reconfigurable Inset-Fed Microstrip Patch Antennas with High Gain for Wireless Sensor Networks

“…With MEMS switches the parameters of an antenna can be controlled as one wanted. The tunable frequency range is about 360 Mhz with required DC voltage in range 0-116 V in [3] or 0.8 to 15 percent of nominal operating frequency in [4]. These antennas tune operating frequency based on change value MEMS varactor located at one of the radiating edges in [3][4] so tuning value is often small.…”

“…The tunable frequency range is about 360 Mhz with required DC voltage in range 0-116 V in [3] or 0.8 to 15 percent of nominal operating frequency in [4]. These antennas tune operating frequency based on change value MEMS varactor located at one of the radiating edges in [3][4] so tuning value is often small. The second type of antenna can tune clearly between two frequencies owing to changing geometry, which is turned ON or OFF by MEMS switches, were reported in [5][6].…”