L-shaped Parasitic Strips Research Articles

A Novel Coplanar-Strip-Based Excitation Technique for Design of Broadband Circularly Polarization Antennas With Wide 3 dB Axial Ratio Beamwidth

In this communication, a novel excitation technique for the design of a single-point-fed compact low-profile wide-slot antennas with broadband circular polarization (CP) and wide 3 dB axial ratio (AR) beamwidth is presented. Two inverted L-shaped parasitic strips placed coplanar to the microstrip line of an asymmetric coplanar waveguide (CPW) and a horizontal strip that protrudes from the vertical edge of the backside ground plane of the substrate are used for CP excitation. The overall footprint of the structure is only $L_{s} \times W_{s} = 0.3\lambda _{0} \times 0.28\lambda _{0}$ when measured at the lowest operating frequency. The antenna prototype has been experimentally validated. The measured results indicate that a wide impedance bandwidth of 72% (2.26–4.85 GHz) and a CP bandwidth of 66% (2.44–4.87 GHz) can be achieved. In addition to the wideband characteristics in terms of the impedance bandwidth and CP, a stable bidirectional radiation pattern with a wide 3 dB beamwidth of 85° ± 5° is obtained for 58% of the total CP bandwidth without involving any complex circuitry. Furthermore, by placing a flat metallic reflector behind the antenna, a unidirectional radiation pattern is produced without changing the geometrical dimensions of the proposed antenna. The average realized gain of the antenna without a reflector is 3.3 dBi, whereas it increases up to 6.3 dBi with the substrate-size reflector.

A Geometrically Simple Compact Wideband Circularly Polarized Antenna

A compact broadband wide-slot circular polarization (CP) antenna is proposed. An inverted L-shaped parasitic strip at the open end of a microstrip line extension and a slot modification is applied to attain wideband CP. The advantage of this technique is simplicity, which makes it readily redesignable for different frequency bands. To demonstrate the concept, three designs working at different frequencies are obtained. The redesign procedure is straightforward and only requires a recalculation of the selected physical dimensions followed by electromagnetic-based parameter tuning. A compact size of 0.09 λ 0 is achieved when measured at the lowest CP frequency. The optimized designs are validated experimentally in terms of | S 11|, axial ratio, realized gain, and radiation patterns. For the design corresponding to the lowest operating frequency, a total impedance bandwidth of ∼89% (3.2–8.4 GHz), axial-ratio bandwidth (ARBW) ≤3 dB of 82% (3.2–7.65 GHz), average in-band realized gain of 3.3 dBi, and a bidirectional radiation pattern with a dual sense of polarization are achieved. A thorough benchmarking indicates the superiority of the proposed antenna over the state-of-the-art designs in terms of all major performance figures.

Compact ultrawideband MIMO dielectric resonator antennas with WLAN band rejection

A new compact configuration of ultrawideband (UWB) multiple-input-multiple-output (MIMO) dielectric resonator antennas (DRAs) with wireless local area network (WLAN) band rejection is proposed. The antenna arrangement consists of two identical inserted rectangular DRAs excited by two microstrip feeds, with an overall compact size of 29 × 29 × 5 mm3. To enhance isolation and improve impedance bandwidth, a stub connected to the ground is added to the bottom plane of the substrate. Further, to reduce interferences with WLAN systems, two L-shaped parasitic strips connected to the dielectric resonators are added to create a band rejection between 4.98 and 6.08 GHz. The measurement results demonstrate that the proposed DRAs achieve satisfactory MIMO UWB performance, with an impedance bandwidth of around 106% excluding a rejection band for WLAN, low mutual coupling and a low envelope correlation coefficient across the whole desired frequency band.

Dual Zeroth-Order Resonant USB Dongle Antennas for 4G MIMO Wireless Communications

A multiband multiple-input multiple-output (MIMO) antenna system consisting of two antenna elements has been proposed for 4G USB dongle application. The designed MIMO antenna system with a compact volume of 25 mm × 30 mm × 3.5 mm operates in two zeroth-order resonance (ZOR) modes to cover the LTE band 13 (746–787 MHz), GSM850/900 (824–960 MHz), and LTE band 7 (2500–2690 MHz) simultaneously. A pair of L-shaped parasitic strips and an etching slot on the ground are employed to achieve good isolation between two elements. Measurement results show that proposed MIMO antenna system has total efficiency over 40% across the operation band and isolation less than −8 dB at the lower band and −16 dB at the upper band, respectively.

A Compact CPW-Fed UWB Antenna with Dual Band-Notched Characteristics

A compact CPW-fed planar UWB antenna with dual band-notched property is presented. The dual band rejection is achieved by etching a C-shaped slot on the radiation patch and two L-shaped parasitic strips in the ground plane. The experimental and measured results show that the proposed antenna exhibits an impedance bandwidth over an ultrawideband frequency range from 2.4 to 12.5 GHz with VSWR less than 2, except for two stopbands at 3.3 to 3.75 GHz and 5.07 to 5.83 GHz for filtering the WiMAX and WLAN signals, respectively. It also demonstrates a nearly omnidirectional radiation pattern. The fabricated antenna has a tiny size, only 32 mm × 32 mm × 0.508 mm. The simulated results are compared with the measured performance and show good agreement. The simple structure, compact size, and good characteristics make the proposed antenna an excellent candidate for UWB applications.

Ultrawideband Dielectric Resonator Antenna With WLAN Band Rejection at 5.8 GHz

A novel compact ultrawideband (UWB) dielectric resonator antenna (DRA) with a band rejection at 5.8 GHz is proposed and studied. The antenna is composed of a thin monopole printed antenna loaded with DR that is housed into a dielectric substrate and an L-shaped parasitic strip connected to the ground plane. The L-shaped strip and metallic sheet are utilized to improve impedance bandwidth. A modified metallic sheet underneath the dielectric resonator has been applied to create a band rejection at frequency 5.8 GHz. The measurement results exhibit acceptable performances in terms of reflection coefficient, radiation pattern, efficiency, and realized gain.

Planar multi-band monopole antenna with L-shaped parasitic strip for WiMAX application

A multi-band design of a planar inverted L-shaped monopole antenna with an L-shaped parasitic strip for the WiMAX system is proposed. With the use of L-shaped monopole and parasitic strips, multi-resonant modes close to the 2.6/3.5/5.5 GHz bands are excited to meet the specifications of the WiMAX system (IEEE 802.16e). Also, obtained impedance bandwidth across the operating bands can reach about 270/1000/1250 MHz for the 2.6/3.5/5.5 GHz bands, respectively. With a nearly omnidirectional pattern in the xy-plane, measured peak gains and radiation efficiencies are about 3.7/3.1/4.8 dBi and 68/80/84% at the 2.6/3.5/5.5 GHz operating bands, respectively.