Slot-coupled Feed Research Articles

A Novel Dual-Feed Slot-Coupling Feeding Technique for Circularly Polarized Patch Arrays

In this letter, a novel slot-coupling feeding technique has been adopted to realize a circularly polarized (CP) 2 × 2 microstrip array. Each array element is fed through two microstrip lines that are excited 90° out of phase (dual-feed technique) and coupled to a square patch by means of a square-ring slot realized in the feeding network ground plane. Design procedure, simulation results, and measurement data are presented for a 2 × 2 array working in the WiMax 3.3-3.8 GHz frequency band (14% percentage bandwidth). Due to both the symmetry properties of the novel slot-coupling feeding configuration and the implementation of a sequential rotation technique, excellent axial ratio (AR) performance is achieved in the WiMax band (AR < 1.35 dB at broadside) and for any direction in the antenna main beam (AR < 2.25 dB at 3.55 GHz). Actually, the 3-dB AR bandwidth is larger than the WiMax frequency band, as it goes up to about 30%.

A Wideband Slot-Coupled Stacked-Patch Array for Wireless Communications

In this letter, a novel slot-coupling feeding technique is used to realize a dual-polarized 2 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\,\times\,$</tex> </formula> 1 microstrip stacked patch array for mobile wireless communication systems. The array is intended as a basic module for base-station linear arrays, whose final size depending on beamwidth and gain requirements. Each array element is fed through two microstrip lines arranged on the basis of a sequential rotation technique. Each stacked square patch is excited through a square ring slot realized in the feeding network ground plane. Design procedure, simulation results and measurement data are presented for a 2 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\,\times\,$</tex></formula> 1 array working in the GSM 1800–1900 band (1710–1910 MHz), UMTS band (1920–2170 MHz), ISM band (2400–2484 MHz), and UMTS 3G expansion band (2500–2690 MHz) or, alternatively, WiMAX band (2300–2700 MHz), with a resulting 45% percentage bandwidth (reflection coefficient <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${&lt;-}$</tex></formula> 10 dB). Due to both the symmetry properties of the novel slot-coupling feeding configuration and the implementation of a sequential rotation technique, good results have been obtained in terms of port isolation and cross-polar radiation patterns.

DEVELOPMENT OF POLYMER-BASED DIELECTRIC RESONATOR ANTENNAS FOR MILLIMETER-WAVE APPLICATIONS

The goal of this paper is to use polymer-based materials (instead of hard ceramics) in fabrication of dielectric resonator antennas at millimeter-wave frequencies. The soft nature of polymers facilitates machining of antennas, while the low permittivity of polymers naturally enhances the bandwidth. More importantly, advantageous properties (e.g., ∞exibility and photosensitivity) of some polymers introduce special capabilities which can not be achieved by ceramics. A photosensitive polymer is utilized in this paper to fabricate polymer-based resonator antennas. As a result, deep X-ray lithography is enabled to produce high quality antenna structures. The proposed dielectric resonator antennas which inherently have very low relative permittivity (usually in a range from 3 to 5) are excited efiectively using a slot-coupled feeding method and analyzed in both the frequency and time domains. Impedance and radiation properties are compared with higher permittivity ceramic antennas. Impedance bandwidths up

Dual-band slot-coupled dipole antenna for 900 MHz and 2.45 GHz RFID tag application

A slot-coupled dipole antenna is presented for dual-band passive RFID tag application. A structure using a slot-coupled feed is explored to achieve dual-band operation. The proposed antenna shows good impedance and radiation characteristics for both bands of interest. The simulated and measured return loss results are in good agreement. Reasonably good radiation characteristics are obtained for 900 MHz and 2.45 GHz RFID bands.

Low-Cost Dual-Polarized Printed Array With Broad Bandwidth

This work presents a novel design of low-cost broad-band dual-polarized microstrip arrays. The antenna uses the slot-coupled feed for one polarization, while the microstrip line feed with slotted ground plane is used for the other polarization. It can make good use of the space on both sides of the ground plane, as the feed circuits for two orthogonal polarizations are placed on each side of the ground plane, respectively. The prototype four-element array designed at C band yields a bandwidth of more than 14% at both ports, and isolation below -30 dB. Good broadside radiation patterns are observed, and the cross-polar levels are below -20 dB at both E- and H-planes.

Dual-polarized dielectric resonator antennas

Two high input-isolation dual-polarized dielectric resonator (DR) antennas are presented in this communication. First, a slot-coupled feed technique with two narrow slots forming a T configuration is employed to design a dual-polarized DR antenna. Input isolation exceeding 35 dB has been obtained in the band for this design. Secondly, a hybrid feed mechanism with a coplanar waveguide (CPW) feed and a slot feed is used to achieve a dual-polarized DR antenna. A vertical strip is added at the center strip of the CPW feed to improve the coupling to the DR antenna. Also, input isolation exceeding 35 dB has been obtained in the band. Good cross-polarization levels less than -20 dB in the broadside direction are attained. The measured far-field radiation patterns are stable in the passband and the measured gains are around 5.5 dBi for the two feed ports of both cases.

Broadband dual-polarized patch antennas fed by capacitively coupled feed and slot-coupled feed

Designs of broadband dual-polarized patch antennas fed by promising feed structures of a capacitively coupled feed and a slot-coupled feed (antenna A), two capacitively coupled feeds of a 180/spl deg/ phase shift and a slot-coupled feed (antenna B), and two capacitively coupled feeds of a 180/spl deg/ phase shift and two slot-coupled feeds (antenna C) are proposed and experimentally studied. The first two feed designs are for the excitation of a single-element broadband patch antenna, while the last design is for a two-element broadband patch antenna. These proposed patch antennas have a thick air substrate, and the 10 dB return-loss impedance bandwidths obtained for the two polarizations are all greater than 13%. High isolation ( 20 dB) in both E and H plane patterns for the two polarizations of antennas B and C are achieved.

Efficient description of impedance and radiation features in printed-circuit leaky-wave structures-an unconventional scattering-matrix approach

This paper presents an original circuit model that furnishes an efficient description of the impedance and of the radiation performance for typical printed-circuit leaky-wave structures. In particular, referring to a junction between slot-coupled feeding and radiating microstrips, we have developed an unconventional equivalent transmission-line formulation, involving the propagation of the dominant mode for the feeding line and of the first higher mode for the radiating line, which is leaky. The quantification of the relevant scattering matrix, achieved with spectral-domain techniques, suitably summarizes the coupling effects and, consequently, the radiative features. Various antenna configurations have been tested, and the relevant results have been validated through comparisons with heavier full-wave numerical approaches. In addition to substantial computational advantages, this innovative approach gives the possibility of treating printed leaky-wave structures in a convenient fashion by means of a network formalism similar to that used in standard microwave circuits.