Differential Feeding Network Research Articles

Ka-Band Omnidirectional High Gain Stacked Dual Bicone Antenna

This communication presents a new omnidirectional antenna based on biconical antenna element to realize high gain and high omnidirectivity at Ka-band. Two biconical antenna elements are stacked and fed differentially by a specially designed differential feeding network embedded inside the antenna. Measurement shows that the $- {10}$ -dB impedance bandwidth of the antenna is 14.2% (26.2–30.2 GHz), within which the antenna can achieve a high gain of around 12.5 dBi corresponding to a sharp 3-dB beamwidth of about 5° in the elevation plane. The ripple of the omnidirectional radiation pattern in the azimuth plane is smaller than ${\pm }{0}.{5}\;{\text{dBi}}$ .

High‐isolation microstrip patch array antenna for single channel full duplex communications

An orthogonally polarised stacked square microstrip patch array antenna structure with high-isolation performance is proposed for single channel full duplex wireless communications. A double symmetric microstrip array structure is collaborated with a special self-interference cancelling network called differential feeding network (DFN) in order to achieve high-isolation performance. The proposed 2 × 2 and 4 × 4 symmetric array antenna structures with the DFNs were designed to operate at the idustrial, scientific and medical band of 2.34–2.54 GHz. By measurement, the average isolation performances of 53 and 60.7 dB were obtained in 200 MHz frequency band by the 2 × 2 and 4 × 4 array antennas, respectively. The measured average gains of the 2 × 2 and 4 × 4 array antennas were found to be 14.4 and 19.4 dBi, respectively.

A Compact, Broadband Spiral Antenna With Unidirectional Circularly Polarized Radiation Patterns

A low-profile, compact spiral antenna with a broadband circularly polarized (CP) response is presented. The antenna is backed by a ground plane and has unidirectional radiation patterns over its entire frequency band of operation. This antenna is a multilayer structure composed of a center-fed modified Archimedean spiral that exploits a novel loading structure, a ring-shaped absorber, and a feed network, which includes a 180° power splitter. The loading structure possesses both inductive and capacitive characteristics, which increase the equivalent electrical length of the antenna while maintaining its maximum dimensions. The Archimedean spiral is integrated into the multilayer dielectric structure along with its differential feed network. An optimized ring-shaped absorber is used on the periphery of the antenna to reduce the ground effects on the antenna performance. The proposed antenna occupies a volume that is 89% smaller than that occupied by a conventional ground-plane-backed Archimedean spiral antenna. At its lowest frequency of operation, the antenna has electrical dimensions of 0.21λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> × 0.21λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> × 0.09λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> , where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> is the free-space wavelength at the lowest frequency of operation (0.5 GHz). Over the frequency range from 0.5 to 1.4 GHz (2.8:1), the antenna has a VSWR of 2.4:1, and it has a CP radiation pattern with an axial ratio better than 1.2 dB. Within this frequency range, the antenna has minimum and maximum realized gain values of -5.0 dBiC and 3.1 dBiC, respectively.

Differentially Fed Planar Aperture Antenna With High Gain and Wide Bandwidth for Millimeter-Wave Application

This paper presents a novel planar aperture antenna with differential feeding. Compared with conventional high-gain aperture antennas, such as horn and reflector antennas, it maintains a high gain and wide bandwidth, but has a much lower profile with only one quarter-wavelength height. Since the height ( ${\lambda_{\bf{g}}}/4$ ) at millimeter-wave (mmWave) band is as low as the most of the commercially available laminates, planar aperture antennas with high gain and wide bandwidth can be realized at mmWave band using the proposed structure. A prototype working at 60 GHz band was designed and fabricated on a single layer laminate using standard printed circuit board (PCB) technology. A differential feeding network based on $E$ -plane tee was also designed to feed the prototype for the measurement purposes. Experiment results show that the prototype achieves a $- 15-{\bf{dB}}$ impedance bandwidth from 56.2 to 69.7 GHz (21.5%). The peak gain at broadside is 15.3 dBi at 60 GHz. The 3-dB gain bandwidth is from 54.0 to 67.5 GHz (22.2%). Within the operating bandwidth, the radiation pattern is stable with a low cross-polarization level below $- 24\;{\bf{dB}}$ , and is symmetrical about both the ${\bm{E}}$ - and ${\bm{H}}$ -planes.

A Wideband High-Isolated Dual-Polarized Patch Antenna Using Two Different Balun Feedings

In this letter, a dual-polarized patch antenna with low profile and wide bandwidth is presented. The square patch, where a bow-tie slot is etched on, is excited by two different balance-to-unbalance feedings for dual polarization. One of the polarizations is excited by the central-placed transition, which transfers the unbalanced microstripline feed to the balanced slot feed. The other polarization is excited by a differential feed network, which contains two capacitively coupled probe feeds. By adopting the two balanced feedings, high isolation and low cross polarization are achieved. A prototype of the proposed antenna is built and tested. Measured results show that the -10-dB reflection coefficient bandwidth of the two polarizations is about 18.8%, with port isolation less than -28.5 dB.