Parasitic Rectangular Patch Research Articles

Performance Enhancement of Broadband Circularly Polarized Slot–Microstrip Antenna Using Parasitic Elements

In this letter, two novel broadband circularly polarized (CP) slot–microstrip antennas (SMPA) with circular and square structures are elaborated. The circular SMPA is composed of four crown patches as parasitic elements, four crown slots etched on a circular ground, and a circular loop sequential phase feeding structure (SPFS). However, the square SMPA consists of four parasitic rectangular patches, four square slots with cut corners, and a square-loop SPFS. In the circular SMPA, the parasitic crown patches and crown slots are used to excite multiple CP resonant modes, which are fed by a circular loop SPFS through capacitive coupling. Combined with these CP modes, the CP bandwidth of the presented antenna could be improved. Eventually, the proposed circular SMPA has a broad 3 dB axial ratio bandwidth of 20.6% (5.20–6.40, 5.8 GHz) and a wide −10 dB impedance bandwidth of 25.8% (4.92–6.38, 5.65 GHz), which could occupy the wireless local area network (5.725–5.85 GHz), ITS (5.8 GHz), and WIFI (5.85–5.925 GHz) bands.

Decoupling of closely stacked patch antennas for airborne radio altimeter applications

In this paper, a mutual coupling reduction technique between closely stacked patch antennas is proposed based on high impedance electromagnetic structure (HIES) in C-band (4.2~4.4 GHz). The considered stacked patch antenna array consists of two dielectric layers, one driven rectangular patch, and four parasitic rectangular patches. The decoupling element composed of two symmetrical rectangular loops embedded into the dielectric and printed at the bottom layer between the driven patches. The decoupling element acting as artificial magnetic conductor (AMC) with very high input impedance. After adding the decoupling unit, the maximum achieved measured port to port isolation is increased from 20 dB to 57 dB with 0.15λ0 edge to edge separation distance at the top layer and the realized gain is approximately 10 dB. The efficiency of the antennas increased from 91% to 95%. Moreover, the envelop correlation coefficient (ECC) is reduced from 0.0017 to <0.0004 and the total active reflection coefficient (TARC) is kept less than 0.2 through the operational bandwidth. The proposed structure is fabricated, and the simulation results are validated using experimental measurements. The measured results indicate that the proposed structure is suitable for airborne radio altimeter antennas and MIMO antenna applications.

2-D Wide-Angle Scanning Phased Array With Hybrid Patch Mode Technique

In this letter, a microstrip patch hybrid mode technique is introduced to design a 2-D wide-angle scanning planar phased array. The proposed element consists of a circular patch and four rectangular parasitic patches distributed around the circular patch. In order to obtain wider radiation beamwidth (BW) in two orthogonal azimuth planes, the TM11 mode of the circular patch and the zeroth-order resonant mode of the parasitic rectangular patches are separately excited. Experimental results show that the proposed element can obtain 3 dB BW more than 156° in the two orthogonal azimuth planes. Moreover, an 8 × 8 planar phased array formed by this element can realize wide-angle scanning in a range of about ±65° in the two orthogonal azimuth planes. In the above scanning range, the sidelobe levels of the phased array are always less than −7.8 dB, the scanning gain fluctuation is less than ±1.73 dB, and the main polarizations on the two orthogonal planes are both θ -polarized. In addition, the phased array has a simple structure, a low profile, and convenient fabrication.

Compact Wideband Circularly Polarized Antenna with Symmetric Parasitic Rectangular Patches for Ka-Band Applications

In this paper, a novel wideband circularly polarized (CP) millimeter wave (mmWave) microstrip antenna is presented. The proposed antenna consists of a central patch and a microstrip line radiator. The CP radiation is achieved by loading a rectangular slot on the ground plane. To improve the 3-dB axial ratio bandwidth (ARBW), two symmetric parasitic rectangular patches paralleled to a central patch and a slit positioned to the right of the central patch are loaded. To verify this design, the proposed antenna is fabricated with a small antenna of 2.88 × 3.32 × 0.508 mm3. The measured impedance bandwidth (IMBW) for S11&lt;−10 dB of the proposed antenna is 35.97% (22.8 to 33.8 GHz). Meanwhile, the simulation result shows that the 3-dB ARBW is 15.19% (28.77 to 33.5 GHz) within impedance bandwidth, and the peak gain is from 5.08 to 5.22 dBic within 3-dB ARBW. The proposed antenna is suitable for CP applications in the Ka-band.

Enhancing Isolation in Dual-Band Meander-Line Multiple Antenna by Employing Split EBG Structure

A closely located dual-band meander-line antenna array with isolation enhancement by inserting novel split electromagnetic bandgap (EBG) uniplanar structure is proposed. The meander-line antenna is coupled to a parasitic rectangular patch to achieve the dual-band operation. Splits are applied on the surface of an EBG structure to cause decoupling at the first resonant mode and utilizing an EBG structure to decouple at the second resonant mode. The prototype of the proposed structure achieves a dual band of 180 MHz (3.42–3.6 GHz) and 400 MHz (4.7–5.1 GHz). The mutual coupling is significantly reduced by 26 and 44 dB at 3.48 and 4.88 GHz, respectively, compared to the reference antenna. In addition, the structure has high front-to-back ratio radiation characteristics.

Improved Design of the Vivaldi Dielectric Notch Radiator With Etched Slots and a Parasitic Patch

A new design to improve the bandwidth and gain of the dielectric notch radiator is proposed. Rectangular slots are etched on both arms of the antenna to change the current density distribution. More resonant frequencies are created to reduce the voltage standing-wave ratio (VSWR) value and widen the bandwidth. A parasitic rectangular patch is introduced in the endfire aperture to enhance the electric field coupling and to produce stronger radiation in the endfire direction. Both changes improve the low- and high-frequency band performance, respectively. Evolution of the feeding structures is described in detail. Uniform-impedance microstrip line and slotline on the ground are designed to simplify the impedance matching and reduce optimized parameters. The proposed antenna prototype is fabricated and tested with the size of 31.5 mm × 41 mm × 0.508 mm. The measured results show that the bandwidth is 6.75–16.15 GHz under VSWR ≤2, and the corresponding realized gain ranges from 3.52 to 9.44 dBi. The measured radiation patterns are in good agreement with the simulated ones, which validates the design concept.

Gain-Improved Broadband Circularly Polarized Antenna Array With Parasitic Patches

A broadband circularly polarized (CP) antenna array with improved gain is proposed. The antenna consists of a CP loop that provides sequential phase, a 2 × 2 patch array, and four parasitic rectangular elements. The square patches are capacitively coupled with four strips, which are connected to the loop feeding network. Moreover, four parasitic rectangular patches are introduced to enhance the gain in the lower band. The measured 10-dB impedance bandwidth is 15.9% (5.01–5.87 GHz), and the 3-dB axial-ratio bandwidth of 640 MHz (5.08–5.72 GHz) is also obtained. Besides, the proposed antenna array has a flat gain over the operating frequency and the maximum gain of 12.5 dBi is achieved at 5.3 GHz.

Wideband high‐gain low‐profile dual‐polarized stacked patch antenna array with parasitic elements

ABSTRACTTo realize wideband high‐gain dual‐polarized radiation, the proposed antenna array consists of two microstrip feeding networks and two groups, altogether 13 metal radiation patches. One group, namely four of the patches, are two‐layer stacked octagonal patches excited by feeding networks directly, and the other group of nine patches, are parasitic rectangular patches for improving both impedance bandwidth and gain level. The height of the antenna array is 7 mm (∼0.083λ0@3.55 GHz). The measured impedance bandwidths for VSWR &lt; 1.5 at both ports are 12.6% (3.35–3.8 GHz). The isolation between the two ports is greater than 20 dB over the whole operating band. The measured gain is 16.2 dBi and the cross‐polarization level is less than −15 dB. The proposed structure possesses the features of low cost, low profile, high gain, wide band, and so forth. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2012–2016, 2015

Proximity fed gap-coupled half E-shaped microstrip antenna array

Broadband gap-coupled array configuration of proximity fed rectangular microstrip antenna with half E-shaped microstrip antennas are proposed. The rectangular slot in half E-shaped patch reduces the orthogonal TM01 mode resonance frequency of equivalent rectangular patch and along with TM10 modes of fed and parasitic rectangular patches, yields broader bandwidth of more than 470 MHz (>45%). An improvement in radiation pattern and gain characteristics over the bandwidth is obtained by gap-coupling half E-shaped patches along all the edges of proximity fed rectangular patch, which yields bandwidth of nearly 510 MHz (∼49%). Further to enhance the gain, a gap-coupled 3 × 3 array configuration of half E-shaped patches with proximity fed rectangular microstrip antenna is proposed. The gap-coupled array configuration yields bandwidth of more than 530 MHz (>50%) with broadside radiation pattern and peak gain of 11 dBi.

A Wideband Open-Slot Antenna With Dual-Band Circular Polarization

A wideband microstrip-fed open-slot antenna with dual-band circular polarization (CP) has been presented. A bent feeding structure and three slots, including a T-shaped and two inverted-L topologies etched in the ground plane, are designed to excite two orthogonal $E$ vectors with equal amplitude and 90 $^\circ $ phase difference (PD) for a radiating right-hand circularly polarized (RHCP) wave at 1.57 GHz and left-hand circularly polarized (LHCP) wave at 2.33 GHz. The two bands are the operated bandwidth of the global positioning system (GPS) and satellite digital audio radio (SDAR) service system. To improve the impedance bandwidth at the low-frequency band, a parasitic rectangular patch is added on the top plane of the substrate. Several resonances are merged, and thus, a wide impedance bandwidth is obtained. The measured impedance bandwidth of a reflection coefficient $ ranges from 1.45 to 3.93 GHz, and thus covers most of the commercial wireless communication systems, such as GPS, DCS, PCS, IMT-2000, WLAN, LTE, and WiMAX. The axial-ratio bandwidths are 65 MHz at the lower band (1.57 GHz) and 107 MHz at the upper band (2.33 GHz).

Design of a Ka Band Microstrip Patch Antenna with Pattern Reconfigurable Characteristic

This letter presents a novel microstrip patch antenna operating in the Ka band (26.5GHz-40GHz) with pattern reconfigurable characteristic. The antenna is provided with one circle patch, two arc patches and four parasitic rectangular patches. The centre patch is connected with the arc patch by a RF MEMS (microelectromechanical systems for RF circuits) switch. The beam can scan in the E-plane by switching the states of the antenna, which is implemented by changing the states of the switches installed in the gap between the patches. Different states of the antenna have different radiation patterns. The two states share the same operating band of 35.6-37.9GHz with the centre frequency of 36.6GHz and their maximum radiation directions are -38° and +37° respectively. The antenna can be applied in radar, satellite, security communications, etc.