Yong-Mei Pan

Wideband and Low-Profile Omnidirectional Circularly Polarized Patch Antenna

A wideband low-profile omnidirectional circularly polarized (CP) patch antenna is proposed and investigated in this communication. The design utilizes two monopolar modes of a circular patch which connects to a modified ground plane by a set of conductive vias, to achieve wide-band impedance matching. The curved branches introduced at the edge of circular ground plane excite a degenerate mode and create CP fields. To verify the design, a prototype operating at 2.4 GHz-WLAN band has been fabricated and measured. Measured reflection coefficient, axial ratio (AR), radiation pattern, and antenna gain agree well with simulation results. The proposed prototype has a low profile of 0.024 λ0, a 10-dB impedance bandwidth of 19.8% and a 3-dB AR bandwidth of 19.3%. To further characterize the design concept, a parametric study of the proposed antenna is carried out using HFSS, and general design guidelines are provided.

High-Gain Filtering Patch Antenna Without Extra Circuit

This paper presents a novel kind of patch antenna with high-selectivity filtering responses and high-gain radiation performance. The proposed antenna is mainly composed of a driven patch and a stacked patch, with its entire height being 0.09λ. Three shorting pins and a U-slot are embedded in the driven patch to enhance out-of-band suppression levels and skirt selectivity near the lower band-edge, whereas the stacked patch provides a sharp roll-off rate at the upper band-edge and also an enhanced gain. Without using extra filtering circuits, the proposed antenna exhibits a quasi-elliptic boresight gain response with three radiation nulls. For demonstration, an antenna is implemented covering the LTE band (2.3-2.7 GHz). The antenna achieves an average gain of 9.7 dBi within passband, and out-of-band suppression levels of more than 21 dB.

A Low-Profile High-Gain and Wideband Filtering Antenna With Metasurface

A low-profile, high-gain, and wideband metasurface (MS)-based filtering antenna with high selectivity is investigated in this communication. The planar MS consists of nonuniform metallic patch cells, and it is fed by two separated microstrip-coupled slots from the bottom. The separation between the two slots together with a shorting via is used to provide good filtering performance in the lower stopband, whereas the MS is elaborately designed to provide a sharp roll-off rate at upper band edge for the filtering function. The MS also simultaneously works as a high-efficient radiator, enhancing the impedance bandwidth and antenna gain of the feeding slots. To verify the design, a prototype operating at 5 GHz has been fabricated and measured. The reflection coefficient, radiation pattern, antenna gain, and efficiency are studied, and reasonable agreement between the measured and simulated results is observed. The prototype with dimensions of 1.3 λ0 × 1.3 λ0 × 0.06 λ0 has a 10-dB impedance bandwidth of 28.4%, an average gain of 8.2 dBi within passband, and an out-of-band suppression level of more than 20 dB within a very wide stop-band.

Dual-Band Base Station Array Using Filtering Antenna Elements for Mutual Coupling Suppression

This paper presents a novel dual-band base station antenna array using filtering antenna elements for size miniaturization. It consists of two 1 × 6 subarrays arranged side by side, which are designed for Digital Cellular System (DCS: 1710-1880 MHz) and Wideband Code Division Multiple Access (WCDMA: 1920-2170 MHz) applications. The two subarrays are composed of filtering antenna elements with high in-band radiation efficiency and out-of-band radiation rejection levels. The radiation of the DCS subarray is suppressed in the WCDMA band and vice versa. Mutual coupling between the two subarrays, therefore, can be suppressed and high isolation can be obtained with reduced subarray spacing. For demonstration, a dual-band filtering antenna array is designed and fabricated. The overall width of the array is only 206 mm, which is much narrower than that of typical industrial products (~290 mm). An isolation of 35 dB is obtained between the two subarrays without any decoupling network. The measured antenna gains are about 14.2 and 14.5 dBi for DCS and WCDMA bands, respectively, and the 3-dB beamwidths of the horizontal radiation patterns are 65° ± 5°. In addition, null filling below the main beam in the vertical radiation patterns is realized by elaborately designing a feed network to manipulate the output magnitude and phase of each array element. The proposed array is suitable for potential base station applications.

Dual-Polarized Filtering Antenna With High Selectivity and Low Cross Polarization

This paper presents a dual-polarized patch antenna with quasi-elliptic bandpass responses. The proposed antenna is mainly composed of a feeding network, a driven patch, and a stacked patch, with its entire height being 0.09λ. The feeding network consists of two orthogonal H-shaped lines that coupled to the driven patch, each for one polarization. The elaborately designed feeding lines not only ensure a sharp roll-off rate at the lower band edge, but also help to achieve low cross polarization and high isolation between two feeding ports. On the other hand, the upper stacked patch provides improved suppression levels at the upper stopband and also an enhanced gain within passband. Consequently, a compact dual-polarized antenna with satisfying filtering performance is obtained, without using extra filtering circuits. For demonstration, an antenna is designed to fit the specification of LTE band (2.49-2.69 GHz). The implemented antenna achieves an average a gain of 9 dBi, a cross-polarization ratio of 29 dB, an isolation of 35 dB within LTE band. The out-of-band suppression level is more than 40 dB within the 2G and 3G frequency bands from 1.71-2.17 GHz. It can be used as the antenna elements in multiband base station antenna arrays to reduce the mutual coupling.

Low-Profile Dual-Band Filtering Patch Antenna and Its Application to LTE MIMO System

This paper presents a low-profile dual-band filtering antenna element and its application to long-term evolution (LTE) multiple-input multiple-output (MIMO) system for wireless customer premise equipments (CPEs). The proposed element consists of two separate U-shaped patches operating at different frequencies and a multistub microstrip feed line. For size miniaturization, the smaller U-shaped patch is embedded in the larger one. In addition, the multistub feed line can generate two controllable resonant modes as well as two nulls in realized gain at the boresight direction. Since the modes of the patches and multistub feed line can be controlled individually, the two operating bands can be tuned to desired frequencies. Also, the radiation nulls in boresight gain can be controlled, high roll-off rate and out-of-band radiation rejection levels are thus obtained. For demonstration, a low profile (0.009λ0) dual-band filtering antenna element operating at 1.9 and 2.6 GHz for TD-LTE applications (B39 and B38-bands) is implemented. Dual-band bandpass responses and four radiation nulls are observed in the experiment. Measured in-band gains are 6.7 and 7.3 dBi, whereas out-of-band gains are less than -10 dBi. Based on this element, a four-element MIMO antenna is further designed for LTE CPEs, where low profile and high integration of multiple components are required. A low mutual coupling of less than -19.2 dB and the low envelope correlation coefficients of better than 0.2 are obtained with a small edge-to-edge spacing of 0.15λ0.

A Compact Filtering Dielectric Resonator Antenna With Wide Bandwidth and High Gain

A rectangular filtering dielectric resonator antenna (FDRA) with low profile, wide bandwidth, and high gain is first investigated in this communication. It is fed by a microstrip-coupled slot from bottom, with open stub of the microstrip feedline elaborately designed to provide two radiation nulls at band edges for a filtering function. A separation is introduced in the slot to provide a good suppression level in lower stopband, while two parasitic strips are parallelly added to the microstrip feedline to offer good suppression in the upper stopband, and consequently, a compact FDRA with a quasi-elliptic bandpass response is obtained without involving specific filtering circuits. Based on the design, a modified DRA fed by a pair of separated slots is proposed to further enhance the gain by ~4 dB. A prototype operating at 5 GHz has been fabricated and measured for demonstration. The reflection coefficient, the radiation pattern, and the antenna gain are studied, and reasonable agreement between the measured and simulated results is observed. The prototype has a 10-dB impedance bandwidth of 20.3%, an average gain of 9.05 dBi within passband, and an out-of-band suppression level of more than 25 dB within a wide stopband.

Wideband Circularly Polarized Dielectric Resonator Antenna With Bandpass Filtering and Wide Harmonics Suppression Response

A wideband circularly polarized (CP) dielectric resonator antenna (DRA) with filtering response was proposed in this communication. To combine additional filtering and harmonic suppression functions within an antenna while realizing circular polarization, a new wideband filtering quadrature coupler was implemented to feed a hollow DRA. The filtering quadrature coupler was based on a snowflake shaped patch, whose operating modes can be flexibly controlled by the loading slots. Quarter wavelength coupled line sections were introduced to the coupler, realizing simultaneously wide bandwidth, excellent bandpass filtering, and wide harmonics suppression characteristics. For demonstration, a filtering CP antenna operating at 1.8 GHz was designed, fabricated, and measured. Reasonable agreement between simulated and measured results was observed. The prototype exhibited excellent bandpass filtering characteristics together with a wide overlapping bandwidth of 27.8%, within which the axial ratio value was less than 3 dB, and return loss was better than 12.4 dB. Over the same band, an average gain of 6 dBic with a variation less than 1 dB was achieved. A rejection level larger than 19 dB was found within the suppression band up to the third harmonic.

Compact differential-fed antenna with filtering response

In this paper, a compact differential-fed antenna with filtering responses is proposed. The antenna is composed of two radiating patches and a differential-fed circuit embedded with two u-shape slots which generate two notches. The stacked patch is employed to further improve the impedance bandwidth to fit the LTE communication application. The proposed antenna achieves the 18% impedance bandwidth. The average gain within the bandwidth is 9.5 dBi with less than 0.5 dB variation. The cross polarization ratio is less than 30dB. Out of the operating band, the gain drops sharply, exhibiting a bandpass response.

Compact Single- and Dual-Band Filtering Patch Antenna Arrays Using Novel Feeding Scheme

This paper presents two compact patch antenna arrays using a novel feeding scheme to integrate bandpass responses. The two arrays have no filtering circuits but reveal high filtering performance. For each array, only a microstrip feed line is coupled to radiating patches and specific coupling regions are employed to obtain the desired current distribution on the radiating patches. In the operating band, the induced currents on the patches are in phase, resulting in high boresight gain. At the out-of-band frequencies, the patches are not excited or the induced currents on them are 180° out of phase, resulting in radiation suppression. Using this method, out-of-band radiation can be suppressed without degrading the in-band performance. For demonstration, a four-element planar patch array is first implemented. Single-band bandpass response is observed in the experiment. Measured in-band gains are 12.6 dBi, whereas out-of-band suppression is more than 20 dB. Then the feeding scheme is employed to design two three-element subarrays to form a planar dual-band patch array. Also, dual-band bandpass responses are obtained with high frequency selectivity.