Z-shaped Slot Research Articles

Direction of arrival (DOA) estimation using switched beam antenna with butler matrix at mm-wave frequency

This paper presents a butler matrix-based microstrip hexagonal patch antenna with a direction of arrival (DOA) estimation approach for mm-wave application. The hexagonal-shaped patch antenna had been designed with a Z-shaped slot with an eight-port butler matrix. The DOA estimation is also done for the switched beam antenna using a novel direction of arrival (DOA) estimation algorithm known as Cramer-Rao lower bound (CRLB). The proposed design leads to significant size reduction and loss minimization. In addition to this, the design had the advantages of being low-cost, lightweight, and small-volume. The entire proposed design provides an operating frequency range of 28 GHz to 39 GHz with a center frequency of 33 GHz. The proposed work makes use of two butler matrices with two 45° phase shifters and 120° phase shifters. The effectiveness of the proposed algorithm and antenna design using the Butler matrix is evaluated for various performance metrics separately. The antenna is designed using Rogers RT/duroid 5880(tm) substrate, and the fabricated prototype is studied. The designed antenna attains high radiation efficiency, and it ranges between 97 and 98 % under both the measures and simulated scenarios under the operating frequency range of 28 GHz to 39 GHz.

A Substrate Integrated Waveguide Bandpass Filter Based on the Modified CSRRs and the Z shaped slot

ABSTRACT In this paper, a substrate-integrated waveguide (SIW) bandpass filter using the modified complementary spilt-ring resonators (MCSRRs) and the Z-shaped slot is presented. Based on the combination of MCSRRs and the Z-shaped slot, four layouts with MCSRRs in different directions are designed and their distributions of electromagnetic fields are analyzed in some detail. Simultaneously, the causes of the passband generation and change are explained. By comparing the performance of the four layouts, a bandpass filter with the advantages of compact structure, easy integration, and low insertion loss is designed on the basis of face-to-face layout. An additional transmission zero is obtained by introducing the Z-shaped slot. The selectivity is improved duo to two transmission zeros. The proposed filter allows the electromagnetic wave to be propagated in the passband below the cutoff frequency of the waveguide characteristic. To validate the design, the filter is fabricated and tested, and the tested results are consistent with the simulated results.

Design of dual band four port circularly polarized MIMO DRA for WLAN/WiMAX applications

This article presents a circularly polarized 4-port Multiple Inputs Multiple Outputs dielectric resonator-based antenna with two resonating bands for WLAN (5.0 GHz) and WiMAX (3.5 GHz) applications. Important attributes of proposed MIMO-DRA are: (i) Bandwidth enhancement is observed due to the use of ring-shaped ceramic material radiator; (ii) Incorporation of rectangular aperture lead to excite the dual hybrid mode in ring DRA, which helps to support dual-frequency range (iii) Circular polarization is achieved in both operating bands by conversion of rectangular to Z-shaped slot; and (iv) mutual coupling among port <−18 dB due to the use of space diversity. The fabricated prototype of the MIMO radiator is measured experimentally, which confirms the dual impedance bandwidth of 3.35 – 3.82 GHz and 5.09 – 5.41 GHz. The proposed antenna is right-handed circularly polarized (RHCP) within the frequency range of 3.54 – 3.72 GHz & 5.04 – 5.16 GHz respectively.

A Wideband Circularly Polarized Dielectric Resonator Antenna Array

In this article, a $2\times 4$ sequentially rotated wideband circularly polarized (CP) dielectric resonator antenna (DRA) subarray with the high gain is proposed in this article. The presented antenna is constituted by four dual-cylindrical ceramic blocks, four Z-shaped slot and a sequentially rotated feeding network, which can provide equal amplitude and orthogonal phase signals. The dual-cylindrical ceramic blocks are used as the radiation element, which is excited by four Z-shaped slots etched on the ground plane based on capacitive coupling way. By combining the dual-cylindrical ceramic blocks with the sequentially rotated feeding network, the presented antenna has a wide 3-dB axial ratio bandwidth (ARBW) of 42.9% (2.4 GHz, 4.40–6.80 GHz), a wide 10-dB impedance bandwidth (IBW) of 52% (2.84 GHz, 4.04–6.88 GHz) and peak gain of 12.5 dBic.

A novel dual-band bandpass SIW filter loaded with modified dual-CSRRs and Z-shaped slot

In this paper, a novel dual-band bandpass substrate integrated waveguide (SIW) filter has been presented by loading two modified dual complementary split ring resonators (CSRRs) and a Z-shaped slot on the top side of SIW. The modified dual-CSRR structure is obtained by folding its outer ring, adding T-shaped branch to its inner ring and placing the splits of the inner and outer rings of CSRR in the same direction. The modified structure allows the electromagnetic wave to propagate in the passband below the cutoff frequency of the waveguide. Compared with conventional CSRR of the same size, it has two passbands and work at a lower frequency. A dual-band bandpass filter is proposed by placing two proposed dual-CRSSs face-to-face on the top side of SIW. In order to improve the performance of the filter, the Z-shaped slot is introduced to enhance the electromagnetic coupling, thus increasing the transmission zero point, broadening the passband and enhancing the flatness in the band, and realizing the center frequency shift of the passband to the left. To validate the design and analysis, a dual-band bandpass SIW filter loaded with two modified dual-CSRRs and a Z-shaped slot is manufactured and measured. The first pass band of the filter has a center frequency of 1.94 GHz, a 3 dB band width of 0.28 GHz, the second pass band has a center frequency of 4.85 GHz and a 3 dB band width of 0.13 GHz, which is basically consistent with the simulation results.

Rectangular DR-based dual-band CP-MIMO antenna with inverted Z-shaped slot

ABSTRACT In this paper, a dual-band circular polarised (CP), Multiple Input Multiple Output (MIMO) antenna with bi-directional polarisation is presented. Designed antenna is operating at two frequency bands i.e. 5.4 GHz–6.2 GHz and 7.0 GHz–7.4 GHz. A rectangular dielectric resonator (DR) is excited by two ports for designing an MIMO antenna system. To generate the Circular polarisation, ground plane is modified by etching an inverted Z-shaped slot. The fundamental mode , and higher order mode , are generated in the antenna structure due to the specified geometry which excites the circular polarisation. 3-dB axial ratio (AR) bandwidth of 300 MHz (5.7 GHz–6.0 GHz) and 200 MHz (7.0 GHz–7.2 GHz) is obtained for the lower and upper bands, respectively. Maximum isolation is 19 dB, and 15 dB for the targeted bands have been achieved. S-parameters, gain and radiation pattern are measured to authenticate the simulated results. Envelope correlation, diversity gain, mean effective gain and channel capacity loss are calculated from the measured parameters; their values lie within the optimum range. Results show that antenna is suitable for WLAN 5.5/5.8 GHz and X-band downlink communication at 7.0 GHz.

Small-Sized UWB MIMO Antenna With Band Rejection Capability

A very compact and small sized 2-element planar Ultra Wide band (UWB) antenna having high isolation with band rejection characteristics designed on a FR4 substrate (23 × 26 × 0.8 mm 3 ) is presented in this paper. Each antenna element have a rectangular stepped-slot and a z-shaped slot, both etched in ground plane. The rectangular slot, proximity fed by a 50 Ω micro-strip transmission line, acts as a main radiator while z-shaped slot acts as a filter for rejecting the full WLAN band (5.15-5.85 GHz). Use of an inverted T-shaped slot near top end of ground plane improves isolation more than 24.5 dB in lower UWB band i.e. 3-5 GHz, while the rectangular vertical slot etched at center of the ground plane near the bottom edge reduces the mutual coupling at lower as well as at higher UWB band i.e. 5 - 10.6 GHz. Both measured and simulated results are presented which are found generally in good agreement.

A Miniaturized Circularly Polarized Implantable Annular-Ring Antenna

A novel miniaturized circularly polarized (CP) annular-ring microstrip antenna with a smooth profile is presented for Industrial, Scientific, and Medical (ISM) band (2.4–2.48 GHz) implantable applications. The radiating element of the antenna consists of an annular ring and a central circular patch. The CP radiation is generated by adding a pair of open stubs in the inner boundary of the annular ring. The antenna profile is minimized by properly cutting two kinds of rectangular slots onto the annular ring. Furthermore, the Z-shaped slot on a central circular patch is implemented for improved axial ratio (AR) and better impedance matching. The volume of the proposed antenna including substrate and superstrate is ${\text{120.69 mm}}^{3}$ , which is smaller than the other CP implantable antennas with similar performance. Simulated and measured −10-dB impedance bandwidth are 8.3% and 11.4%, respectively. The simulated 3-dB AR bandwidth is 2.49%. In addition, the radiation and specific absorption rate performance of the antenna are also characterized. It is a capable candidate for implantable applications.

Gain Enhancement of Ground Radiation Antenna for RFID Tag Mounted on Metallic Plane

A novel design for a radio-frequency identification (RFID) tag antenna mounted on a metallic plane is presented. The tag antenna has a rectangular radiating plate with a Z-shaped slot, which enables it to function like a half-wavelength slot resonator and a dipole-type ground radiator. A conjugate match to an Alien Higgs-3 chip with an impedance of 8 – j 142 $\Omega$ at 925 MHz is obtained by etching a half-wavelength slot resonator in the center of the rectangular radiating plate ( $120 \text{ mm}\times60\text{ mm}$ ). The tag antenna resistance and inductive reactance can be matched to the desired chip impedance by simply tuning the length and width of the Z-slot resonator. The space between the half-wavelength resonant radiating plate (dipole-type ground radiator) and the metallic plane enhances the antenna gain by increasing the reflection from the metallic plane. A horizontal electric dipole placed above the perfectly flat electric metallic plane enables a maximum gain of 8.7 dBi over a short distance, which is fourfold higher than that of an isolated half-wavelength dipole. Tests of an RFID reader with an effective isotropic radiated power of 4.0 W showed that the maximum read coverage of the proposed tag antenna mounted on a metallic plane exceeded 10 m. Measurement data were in good agreement with the simulation results.