Low-Profile Steerable Loop Antenna With Capacitively Coupled Feeds

Abstract

A novel application of capacitively coupled feeds for making a switched beam square loop antenna (SLA) matched to 50 at its inputs is presented. The capacitively coupled feeding mechanism introduces capacitance into the antenna input impedance, which cancels out the high dominant inductance due to the probe and the ground plane, and helps in the realization of low-profile SLA. The net thickness for an antenna developed for the test frequency of 4.7 GHz is 3.04 mm ( ) and has four feeding ports. In order to obtain a tilted beam by this antenna, there must be a gap in the middle of side lengths of the antenna. When one of the ports is excited and the three remaining ports are open-circuited, the antenna generates a linearly polarized tilted beam directed toward the quadrant opposite to the excited port. Thus, by exciting one port at a time and open-circuiting the other three, the antenna can steer the beam in four different quadrants and scan the entire space in front of antenna. The antenna developed has an impedance bandwidth of 270 MHz and an average directivity of 7.6 dBi. Index Terms-Beam-steerable antenna, capacitive feed, low-profile antenna, square loop antenna (SLA).

Dual-Band Low-Profile Capacitively Coupled Beam-Steerable Square-Loop Antenna

“…To tackle this problem, a capacitively coupled feeding technique [13]- [14] is developed to match the thin substrate SLA to the 50Ω feed line. The capacitive coupled feeds introduce appropriate capacitance into the input impedance of the antenna.…”

“…Thus, the new feeding mechanism allows the radiating square loop to be placed very close to the conducting ground plane. The proposed Capacitively Coupled Square Loop Antenna (CCSLA) is similar to [13]- [14] and has a net substrate thickness of 3.04 mm (i.e. : λ 0 /26) at the operating frequency.…”

A Four-Arm Circularly Polarized High-Gain High-Tilt Beam Curl Antenna for Beam Steering Applications

“…These antennas are capable of directing the beam only toward the intended direction avoiding the interference/noise sources [3] [4]. Consequently, these antennas provide better signal to interference ratio (SIR) enabling the communication system to support high-rate data-transmission.…”

A low-profile switched-beam dual-band capacitively coupled Square Loop Antenna

“…Thus, the new feeding mechanism allows the radiating square loop to be placed very close to the conducting ground plane. The proposed Dual Band Capacitively Coupled Square Loop Antenna (DBCCSLA) is similar to [9]- [10] and has a net substrate thickness of 3 mm (i.e. : λ 0 /24 at the operating frequency of 4.1 GHz).…”