This paper designs, fabricates, and analyzes an inductively-tuned K/Ka band RF MEMS (Radio frequency micro-electro-mechanical-systems) capacitive switches. The MEMS switch employs a defect ground structure (DGS) and an air bridge. Two different MEMS switches, one with air bridges and the other not, are designed. Surface current distribution results of MEMS switches in different states are simulated and discussed. A novel actuation voltage's calculation approach of MEMS switch is proposed. Measured results indicate that the type MEMS switch's actuation voltage is 20 V. For the MEMS switch without air bridges, the isolation is more than 15 dB from 12.5 to 20 GHz, and the insertion loss is less than 0.28 dB up to 20 GHz. For the MEMS switch with integrated air bridges, the isolation is more than 15 dB from 18.3 to 40 GHz, and the insertion loss is less than 0.64 dB up to 40 GHz. Circuit models and measured results of the proposed MEMS switches show good agreements. The pull-in and release time of this switch are 99 µs and 49 µs, and the lifetime of this type of switch is more than three million.
This paper proposes a novel RF MEMS capacitive shunt switch, which is applied in Kband (18 ∼ 26.5 GHz). The characteristic impedance matching of the RF MEMS switch is achieved by discontinuous coplanar waveguide (DCPW) structure. Two actuation poles are located at the bottom of the fixed-fixed beam, and they are covered with a dielectric layer of SiN. The pole's thickness is less than that of CPW signal, to avoid the phenomenon of dielectric charging between the beam and the pole. The proposed MEMS switch is fabricated on 400 µm-thickness high resistivity silicon, using the MEMS surface micromachining process. Measured results demonstrate that, at K-band, the return loss is better than 22 dB, and the insertion loss and isolation are better than 0.5 and 17 dB, respectively. The on/off switched time is 168/54 µs when the DC bias voltage is 0/54 V. This proposed MEMS switch provides a solution for K-band communication system applications.
In this paper, a K-band right hand circularly polarized (RHCP) antenna array with 4 × 4 elements is designed, fabricated, measured, and analyzed. The RHCP pattern is obtained from the helical antenna elements, with a unit cell of every four elements, sequentially counterclockwise by 90 deg. To decrease the profile of the vertical interconnection between the helical antenna and its feeding network, the integration of this RHCP antenna and its feeding network is realized by low temperature co-fired ceramic (LTCC) technology. The antenna's feeding network consists of eight directional couplers, four circulators, and one power divider. In the feeding network, different RF channels' isolations are improved by the shield structures which are realized by metal filled via holes. For the operating frequency, the measured axial ratio (AR) is better than 1.25 dB. The proposed antenna is small in size, and it is a very good candidate for mobile satellite communications.
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