Operation principle and design approach of a novel planar end-fire circularly polarized (CP) complementary antenna is proposed. A vertically polarized printed magnetic dipole and a horizontally polarized printed dipole are combined on the same substrate, and a planar CP antenna with end-fire beam in parallel with its plane is thus designed. Prototype antennas centered at 5.80 GHz are then fabricated and measured to validate the operation principle and the design approach. The experimental prototype reported that the impedance bandwidth ( $20\text{log }\vert\text{S}_{11}\vert ) is about 1.90%, from 5.75 to 5.86 GHz and the 3-dB axial ratio (AR) bandwidth is about 14.48%, from 5.19 to 6.00 GHz. Therefore, the proposed design is applicable as a low-profile handheld reader antenna in radio-frequency identification (RFID) systems.

A Planar End-Fire Circularly Polarized Complementary Antenna With Beam in Parallel With Its Plane

A novel planar end-fire circularly polarized (CP) complementary Yagi array antenna is proposed. The antenna has a compact and complementary structure, and exhibits excellent properties (low profile, single feed, broadband, high gain, and CP radiation). It is based on a compact combination of a pair of complementary Yagi arrays with a common driven element. In the complementary structure, the vertical polarization is contributed by a microstrip patch Yagi array, while the horizontal polarization is yielded by a strip dipole Yagi array. With the combination of the two orthogonally polarized Yagi arrays, a CP antenna with high gain and wide bandwidth is obtained. With a profile of $0.05\lambda _{\mathrm{0}}$ (3 mm), the antenna has a gain of about 8 dBic, an impedance bandwidth ( $\vert S_{11}\vert dB) of 13.09% (4.57–5.21 GHz) and a 3-dB axial-ratio bandwidth of 10.51% (4.69–5.21 GHz).

A Broadband and High-Gain Planar Complementary Yagi Array Antenna With Circular Polarization

A novel circularly polarized (CP) complementary source antenna with endfire radiation is proposed in Ka-band. With the existence of two antipodal notches etched at the edges of the two broad walls of an open-ended substrate-integrated waveguide, two orthogonal electric field components radiated from the equivalent magnetic current, and the electric currents separately can be excited simultaneously. The magnitude and phase differences between the two filed components can be controlled effectively by properly tuning the dimensions of the notches. The operating mechanism and the design procedure of the antenna are analyzed in detail. Wide −10 dB impedance and 3 dB axial ratio bandwidths of 64% and 51%, a gain varying from 3.1 to 6.4 dBic, and the symmetrical radiation pattern are obtained. In order to further increase the gain and front-to-back ratio (FTBR) of the antenna, a dielectric rod structure is then integrated with the antenna. An overlapped operating bandwidth of 41%, an improved gain up to 12 dBic and the stable radiation pattern with an FTBR close to 20 dB are verified by a fabricated prototype. The antenna presented in this paper provides a new mean to design the wideband endfire CP antenna with a simple configuration, which would be attractive for future millimeter-wave wireless systems.

Millimeter-Wave Wideband Circularly Polarized Planar Complementary Source Antenna With Endfire Radiation

A novel wideband planar endfire circularly polarized (CP) antenna with wide 3 dB axial ratio (AR) beamwidth is presented. The operation principle of the proposed CP antenna is described at first through the combination of a planar magnetic dipole and a V-shape open loop. Then, it is demonstrated how its AR beamwidth can be precisely controlled with resorting to the shape and thickness of the open loop element. Finally, the theoretical design approach is numerically verified, and the results are then experimentally validated. It is observed that a 3 dB AR beamwidth is achieved in an extremely wide angular region up to 250° within the principal elevation plane over a frequency range of 2.41–2.51 GHz. The proposed antenna has exhibited a wide impedance bandwidth of 22.23% in fraction, a 3 dB AR bandwidth of no less than 8.00% in fraction, and a simple planar profile in geometry. In addition, its endfire beam is in parallel with its plane.

A Novel Planar Endfire Circularly Polarized Antenna With Wide Axial-Ratio Beamwidth and Wide Impedance Bandwidth

A new planar quasi-magnetic–electric circularly polarized (CP) antenna is proposed. The antenna has a simple planar structure with a small size and a single feed, and produces an omnidirectional CP radiation pattern. It is based on a quarter-wave shorted patch connected with two printed strips. The tangential electric field at the main open aperture of the shorted patch can be considered as an equivalent magnetic current, while the two strips contribute two electric currents. With a single feed, the proposed antenna exhibits an inherent phase difference of about 90° for the two kinds of currents, and therefore, a CP radiation is obtained. The antenna is designed and fabricated. Measured results show that the antenna has an impedance bandwidth of 4.3%. In the band of interest, the antenna generates a circular polarization and an omnidirectional pattern in the plane perpendicular to the magnetic and electric currents, with an average axial ratio below 1.5 dB and a gain between 2.4 and 3.3 dBi.

A Planar Quasi-Magnetic–Electric Circularly Polarized Antenna

A novel planar circularly polarized antenna with endfire radiation beam in parallel with the antenna substrate’s plane is proposed. The operation principle of the antenna is analyzed and design guidelines are laid down. Then, an optimized loop-aperture combined antenna is designed and demonstrated to exhibit an endfire beam in parallel with its plane within 5.74-5.88 GHz for $\vert{{\rm S}_{11}}\vert$ lower than $-10~\hbox{dB}$ and axial ratio smaller than 3 dB. The proposed antenna can be used as a low-profile, cost-effective, hand-held reader antenna for radio frequency identification systems .

Jing-Wen Shi

Papers

Planar Endfire Circularly Polarized Antenna Using Combined Magnetic Dipoles