Mathieu Caillet

A New Wideband Circularly Polarized Hybrid Dielectric Resonator Antenna

Dielectric resonator antennas (DRAs) have been targeted in the past two decades as a potential solution for wideband antennas. Although DRAs offer wider frequency band and smaller size than patch antennas, their design to obtain good circular polarization over a wide frequency band can be challenging. In this letter, a new hybrid DRA has been investigated to produce circular polarization over a wide frequency band. The targeted application is to produce a compact antenna for satellite navigation systems. The obtained design was fabricated and measured, showing impedance matching from 1.08 to 1.82 GHz, i.e. over 50% bandwidth. The radiation characteristics of the antennas were also characterized. The achieved gain is over 1.5 dBic, and the axial ratio (AR) is under 1 dB at boresight over the 1.131.63 GHz frequency band. The half-power beamwidth is greater than 75°, and the axial ratio beamwidth (AR < 3 dB) is over 100° .

A Compact Wide-Band Rat-Race Hybrid Using Microstrip Lines

A compact microstrip rat-race hybrid with a 50% bandwidth employing space-filling curves is reported in this letter. The footprint of the proposed design occupies 31% of the area of the conventional similar design. Across the frequency bandwidth, the maximum amplitude unbalance is 0.5 dB, the phase variation is plusmn5deg , the isolation is better than 25 dB and the return loss is greater than 10 dB. Moreover, the circuit is planar, easy to design, and consists of only one layer without requiring plated thru holes, slots or bonding wires.

A Broadband Folded Printed Quadrifilar Helical Antenna Employing a Novel Compact Planar Feeding Circuit

A broadband printed quadrifilar helical antenna employing a novel compact feeding circuit is proposed in this paper. This antenna presents an excellent axial ratio over a wide beamwidth, with a 29% bandwidth. A specific feeding circuit based on an aperture-coupled transition and including two 90° surface mount hybrids has been designed to be integrated with the quadrifilar antenna. Over the bandwidth, the measured reflection coefficient of the antenna fed by the wideband compact circuit has been found to be equal to or lower than -12 dB and the maximum gain varies between 1.5 and 2.7 dBic from 1.18 to 1.58 GHz. The half-power beamwidth is 150°, with an axial ratio below 3 dB over this range. The compactness of the feeding circuit allows small element spacing in array arrangements.

A Compact Circularly Polarized Antenna Using an Array of Folded-Shorted Patches

The development and optimization of a circularly polarized (CP) antenna using an array of four folded-shorted patch elements is investigated. The realized antenna is compact ( 0.2λ0 by 0.2λ0), highly integrated, and offers good radiation performance at 400 MHz. A compact coupler-based feeding network for the four elements within the array, integrated into the antenna ground plane, provides a sequential 90° phase difference between the radiating folded-shorted patches. This very compact CP antenna design may be useful for microsatellite and other miniaturized phased array systems for communications.

Compact Differentially Fed Inverted Microstrip Circular Patch With an Integrated Coupler

This letter presents a compact design of an inverted microstrip circular patch differentially fed by an integrated coupler. The compact design offers symmetric copolarized radiation in both principal planes and low cross-polarized radiation in the H-plane. A relatively high gain of 8.3 dBi is experimentally demonstrated. Moreover, the integrated unilayer coupler feed shares a common ground plane with the inverted patch providing a compact design.

A Compact Wideband Dielectric Resonator Antenna with a Meandered Slot Ring and Cavity Backing

We design a compact cavity-backed antenna structure where a dielectric resonator (DR) element is surrounded by a meandered circular slot ring to enhance radiation efficiency. The DR for the antenna is cylindrical in shape, and four degenerate HE11δ modes are excited and driven by four, quadrature-fed aperture-coupled slots. Such a compact implementation hybridizes operation of the DR with the miniaturized ring as well as the four aperture-coupled slots for circular polarization. Measured realized gain values are greater than 5 dBic from 1.14 to 1.55 GHz defining a bandwidth of more than 30%. In addition, the half-power and 3-dB axial-ratio beamwidths were measured to be more than 100 ° and 200 °, respectively. The proposed design technique to employ such a secondary meandered slot ring may also be useful to improve antenna gain, bandwidth, and efficiency for other antenna and array structures.

Wideband circularly polarized antenna elements for GPS/GNSS applications developed at DRDC Ottawa

This paper presents several wideband circularly polarized antennas for GPS/GNSS applications that have been developed at Defense Research & Development Canada – Ottawa. Three radiating elements were designed using different technologies. All of them exhibit very good performance in terms of impedance matching, coverage, gain and axial ratio over the entire GNSS frequency band (1.15 GHz to 1.62 GHz). Their characteristics are presented and compared in terms of EM performance and size.

Millimeter Wave Reconfigurable Antenna Based on Active Printed Array and Inhomogeneous Lens

This paper deals with radiation pattern reconfigurable antenna in millimetre wave range. An active printed antenna array is designed in 24 GHz band and feed an inhomogeneous lens (Half Maxwell Fish Eye) to obtain reconfigurable patterns and in particular sectorial and directive cases. In the first part, the authors describe a four patches multilayer active array which allows achieving radiation pattern control by associating a commutator to each element and by changing the fed patches number. In a second part, this array feed an inhomogeneous lens to shape radiation pattern.

A phased array simulation tool for synthesized array factors having multiple beams and/or multiple nulls

This article presents a phased array simulation tool (PAASoM) developed to synthesize radiation patterns of arrays of any geometry having multiple beams and/or nulls considering the characteristics of the phased array components, such as the antenna elements, the phase shifters and the amplifier or attenuators. Through a graphic user interface or a text input file, the user describes the problem under study, the array features and the results of interest. PAASoM allows qualitative and quantitative studies, and uses an unconventional but highly descriptive graphic visualization to present the overall radiation characteristics over a frequency or scanning range of interest.

Amplitude and phase quantization effects on synthesized array factors including one beam and one prescribed null

In this article, investigations into the amplitude and phase quantization effects for a 16-element linear array with half-wavelength element spacing and digital phase shifters are reported for an array factor having a main beam and a prescribed null. The main beam is fixed, and the prescribed null angular position varies between 1 and 60°. Based on results with ideal amplitude and phase, the effects of phase quantization on the radiation characteristics are studied for several main beam positions. Particularly, one can notice that the main beam angular position and half-power beamwidth errors are similar to the results with exact phase. However, phase quantization greatly affects the prescribed null position and depth.