Design and Experiment on Differentially-Driven Microstrip Antennas

Abstract

Design and experiment is given of differentially-driven microstrip antennas. First, the design formulas to determine the patch dimensions and the location of the feed point for single-ended microstrip antennas are examined to design differentially-driven microstrip antennas. It is found that the patch length can still be designed using the formulas for the required resonant frequency but the patch width calculated by the formula usually needs to be widen to ensure the excitation of the fundamental mode using the probe feeds. The condition that links the patch width, the locations of the probe feeds, and the excitation of the fundamental mode is given. Second, the wideband techniques for single-ended microstrip antennas are evaluated for differentially-driven microstrip antennas. A novel H-slot is proposed for differentially-driven microstrip antennas to improve impedance bandwidth. Third, the effects of imperfect differential signal conditions on the performance of differentially-driven microstrip antennas are investigated for the first time. It is found that they only degrade the polarization purity in the H-plane with an increased radiation of cross-polarization. Finally, both differentially-driven and single-ended microstrip antennas were fabricated and measured. It is shown that the simulated and measured results are in acceptable agreement. More importantly, it is also shown that the differentially-driven microstrip antenna has wider impedance bandwidth of measured 4.1% and simulated 3.9% and higher gain of measured 4.2 dBi and simulated 3.7 dBi as compared with those of measured 1.9% and simulated 1.3% and gain of measured 1.2 dBi and simulated 1.2 dBi of the single-ended microstrip antenna.

A Novel Tunable Microstrip Patch Antenna Using Liquid Crystal

“…No bias tee is needed. The novel tunable microstrip patch antenna structure fully explores the advantages of the stacked patches, differentially driving and aperture coupling [14][15][16]. In particular, the radiation efficiency is higher when the patch width of the microstrip antenna is larger.…”

“…Generally, the patch width is limited because of the undesirable influence of higher-order modes. Higher-order modes can be significantly suppressed for the differentially-driven microstrip antenna, so the radiation efficiency of the differentially-driven microstrip antenna can be much higher than that of the single-ended counterpart [15], differentially driving operation is used in the novel antenna so that the radiation efficiency is higher. It is particularly suitable for highly-integrated solutions of modern wireless systems [17][18][19].…”

A Novel Wideband Magneto-Electric Dipole Antenna with Improved Feeding Structure

“…Besides this, differentially fed antennas introduce a cancellation mechanism that helps to suppress some higher-order modes and unwanted radiation from vertical feeding structures (e.g. a feeding probe), to reduce the cross polarization radiation and thus enhance the polarization purity [1][2][3][4][5]. Recently a new wideband "Magneto Electric Dipole Antenna" has been proposed by K.M.Luk et al [6][7], and it has been originated from the researches made in the designs of complimentary antenna.…”

Dual-Band Circularly Polarized Antenna With Differential Feeding

“…Moreover, there is increasing interest in antennas with differential signal operation recently [12][13][14][15][16]. This is because the differential signal operation is more suitable for radio frequency integrated circuits [12].…”