Ronald Joseph

BANDWIDTH ENHANCEMENT OF CIRCULARLY POLARIZED SQUARE SLOT ANTENNA

Bandwidth enhancement technique of circularly polarized square slot antenna is presented in this paper. A square slot antenna with the components of L-probe separated could achieve an axial ratio (AR) bandwidth of 33.84%. Placing Stubs in the slot by studying the electric fleld behaviour could enhance the AR bandwidth by around 10%. Creating an L-shaped slot on the ground plane, where the electric fleld rotates in the desired clockwise direction, can further enhance the bandwidth by 7%. A < i10dB S11 bandwidth of 46.15% and < 3dB AR bandwidth of 50.35% could be achieved with the present design. Unidirectional patters are obtained by having a cavity at the wide slot of the antenna and shows a measured bandwidth of 41.79% in S11 and 44.97% in AR. Both antennas show a cross polarization discrimination of more than 15dB on a wide azimuth range. The measured results well comply with the simulated results.

Circularly polarized broadband antenna with circular slot on circular ground-plane

A novel circularly polarized antenna with a circular radi- ating aperture and circular ground plane for broadband characteristics is presented in this paper. The vertical and horizontal components of the L-shaped probe are separated and placed at the front and back sides of the substrate. The antenna is excited by a microstrip line which is connected to the vertical component of the L-shaped probe and electromagnetically couples the signal to the horizontal compo- nent of the L-shaped probe. The concept of placing an appropriate stub in the slot, by observing the electric fleld vector behaviour in the slot, is proposed to enhance the axial ratio (AR) bandwidth by around 15%. The fabricated antenna shows wideband impedance and circu- lar polarization characteristics of 48% along with a maximum gain of 6dBic. The measured and simulated antenna characteristics are in good agreement.

Circular slot antennas using L-shaped probe for broadband circular polarization

Novel circularly polarized antennas with a circular radiating aperture for broadband characteristics are presented in this paper. The vertical and horizontal components of the L-shaped probe are separated and placed at the front and back side of the substrate. The antennas are excited by a microstrip line which is connected to the vertical component of the L-shaped probe and electromagnetically couples the signal to the horizontal component of the L-shaped probe. A novel concept of placing stub in the slot of a planar antenna, by observing the electric fleld vector behaviour in the slot, is proposed to enhance the axial ratio (AR) bandwidth by around 10%. Unidirectional patterns can be obtained by having a cylindrical cavity of height ‚g=4 behind the antenna and is efiective when no stubs are placed in the slot. A < 3dB AR bandwidth of 39.5% with cavity and 41.18% without cavity but with stub in the slot is obtained in simulation and the results well match with the measurement.

Design of broadband circularly polarized aperture antennas using L-shaped bent probe

In this paper, the authors present some designs of broadband CP antenna with a L-shaped bent probe. The bandwidth can be expanded to 50% at the center frequency. Furthermore, a design way with observing the behavior of electric field and current distribution is presented where the behaviors are controlled by additional metallic patches and slots to control the current and electric field behavior for improving the antenna performances.

Broadband circularly polarized antenna with circular sot and separated L-probes

Circularly polarized antennas have been extensively studied recently and received much attention because of its alluring applications in satellites, RADARs, GPS and mobile communications [1]-[2]. Circular polarization is beneficial because most of the future applications require design freedom of not requiring alignment of the electric field vector at the receiving and transmitting locations.

Broadband circularly polarized cavity-backed antenna

The design and experimental investigation of a circularly polarized antenna with circular slot for broadband characteristics is proposed. The horizontal and vertical probes of the L-shaped probe, which is a key element to generate circular polarization, are separated in the structure, contrary to the concept of having joined probes. Another novelty of placing stubs in the slot, which are attached to the ground plane, is proposed to improve the axial ratio (AR) characteristics of the antenna by around 10%. Unidirectional patterns can be obtained by having a cavity of height Ig/4 behind the antenna and is effective when no stubs are placed in the slot.

A novel circularly polarized broadband antenna with separated L-probes

In order to achieve broadband characteristics in impedance matching and axial ratio as well as to reduce the cross polarization, a novel circularly polarized antenna is simulated, fabricated and measured. The antenna uses a square slot, but the novelty in the structure is that the horizontal and the vertical probes of the L-shaped feeding probe are separated and fabricated on the front and back side of the structure. The proposed antenna could substantially reduce the cross polarization and variation in phase difference characteristics. A good agreement between the simulated and measured results is achieved. The test antenna was found to have good S11 characteristics, axial ratio and radiation characteristics.

Square slotted circularly polarized antennas with separated L-probes for broadband characteristics

Broadband circularly polarized antennas with a square slot are developed and discussed in this paper. The L-shaped probes that generate circular polarization are separated in the structure. An additional stub attached to the ground plane enhances the antenna characteristics, achieving a bandwidth of 43.9% (2.39-3.75GHz) in axial ratio ≪3dB and 46.48% (2.84-4.56GHz) in return loss ≪10dB. Good agreement between measured and simulated result is achieved.