Zhe-Jun Jin

Simultaneous Frequency and Isolation Reconfigurable MIMO PIFA Using PIN Diodes

A reconfigurable multiple input multiple output (MIMO) planar inverted-F antenna (PIFA) is presented for three worldwide m-WiMAX bands: 2.3-2.4 GHz, 2.5-2.7 GHz, and 3.4-3.6 GHz. In order to achieve low mutual coupling, i.e., high isolation, a band-notched quarter-wave slot line on the ground plane is used between the two reconfigurable antennas. Two PIN-diodes are appropriately located on the slot line in order to electrically control the slot length. By adjusting both the PIN-diode biases for the reconfigurable antennas and the reconfigurable isolation slot, the proposed antenna simultaneously obtains the operating frequency and isolation reconfigurability for the three operating bands. A parametric analysis is performed to investigate optimized slot lengths for the three operation modes. All of the simulated results are confirmed with measurements. Measured isolation performance of greater than 30 dB improves the radiation efficiency, diversity gain, and channel capacity for all operating frequencies.

Compact Wideband Open-End Slot Antenna With Inherent Matching

A compact wideband open-end slot antenna is proposed for DCS, PCS, UMTS, WLAN, and WiMAX band applications. The antenna is composed of an open-ended slot and a central line within the slot. The open-end slot decreases the antenna size in half, compared to a conventional slot-ring antenna. Furthermore, the narrowed slot and central line miniaturize the antenna and obtain wideband performance using the inherent impedance-matching network of the central line. The proposed antenna obtained an omnidirectional radiation pattern with an antenna gain of larger than 1 dBi and an antenna efficiency of greater than 50% over 1710-3660 MHz.

Equivalent-Circuit Modeling for Multilayer Capacitors Based on Coupled Transmission-Line Theory

This paper provides a novel modeling methodology for multilayer capacitors (MLCs) based on the coupled transmission-line theory. From an analytical solution of a single-layer capacitor, first- and second-order equivalent-circuit models for an N-layer capacitor are introduced using an infinite series approximation. The models demonstrated accurate prediction of the behavior of MLCs up to the first and second self-resonant frequencies. In addition, distributed physical parameters for the models were extracted directly from S-parameter measurements without an optimization process. High-frequency MLCs were measured up to 20 GHz using a vector network analyzer and compared with models from 1 to 47 pF.

Small antennas combining multiple bands with MIMO techniques

A small PIFA using multi-band, wide-band, high-isolation MIMO techniques, covering GSM900/DCS/PCS/UMTS/WLAN operational bands, has been demonstrated using both simulations and measurements. In order to achieve the wide bandwidth required for DCS/PCS/UMTS services, a resonator and a meander shorting line were adopted. In addition, a modified neutralization link was incorporated to obtain the high isolation characteristic necessary for a MIMO WLAN service. Simulations and measurements demonstrated very similar results for S-parameters, ECC, and radiation patterns. In addition, Good diversity characteristics for the WLNA band are also achieved. Therefore, the proposed antenna combining a multi-band antenna with MIMO antennas will be useful for future mobile handset applications.

Patterned Helical DVB-T Antenna With an Open Stub and a Matching Network

A miniaturized embedded digital video broadcasting-terrestrial (DVB-T) antenna with a patterned helical structure is proposed for mobile broadcasting. An open stub and a matching network are used in order to achieve a compact size and a wide bandwidth, respectively. The antenna has a volume of 58.83.29 mm3, which is small enough for use in mobile handsets. The measured results satisfy the DVB-T bandwidth requirements from 174 to 230 MHz and show omnidirectional radiation patterns with antenna gains ranging from -21 to -11 dBi.