Design of square-ring microstrip antenna for circular polarisation

The design of a square-ring microstrip antenna with circular polarisation (CP) is presented. To compact the antenna size and overcome the high impedance problem, the CP antenna is excited by a coupling strip located inside the square-ring patch. Several prototypes of the square-ring CP antennas with various substrate thickness (0.013-0.09/spl lambda//sub 0/) have been constructed and studied experimentally, and their coupling-strip designs and CP performance are described.     

Dual-frequency microstrip antenna with dual circular polarisation

A single-feed dual-frequency microstrip patch antenna that can produce dual circular polarisations (CP) is presented. The microstrip antenna has an annular-ring patch and is excited by an L-shaped microstrip line through the coupling of a ring slot in the ground plane. The occurrence of the dual CP is because the magnetic currents circulating along the ring slot at two specific frequencies have opposite flowing directions. Both simulated and measured results are provided to validate the CP performance of the proposed antenna     

单馈电双模方形微带天线及圆极化实现收稿

基于展开理论,给出了沿贴片对角线馈电时方形微带天线的内场分布和输入阻抗公式.通过在贴片四周切割缝隙,有效地降低了天线双主模的谐振频率并实现了圆极化辐射,讨论了缝隙长度与天线极化之间的关系.为实现微带天线的小型化提供了一种新途径,给出了UHF波段天线设计实例.     

Slot-coupled microstrip antenna for broadband circular polarisation

Broadband circular polarisation (CP) operation of single-feed slot-coupled microstrip antennas is achieved using an inclined nonlinear coupling slot. This nonlinear slot, end-loaded with two V slots, significantly broadens the CP bandwidth to about 2.1 times that obtained using a simple inclined coupling slot for CP operation. Details of the antenna design are described, and experimental results of the CP performance are presented     

Slot-coupled microstrip antenna for broadband circular polarisation

A microstrip antenna with broadband circular polarisation (CP) is presented. The proposed microstrip antenna has a circular patch and is excited by a series microstrip-line-feed configuration through the coupling of a ring slot in the ground plane. The broadband operation is achieved by coupling two CP resonant elements, which are due to the circular patch and the ring slot, respectively. A typical prototype using foam material of thickness 5 mm as the antenna substrate is constructed. Measured results show the 3 dB-axial-ratio bandwidth centred at 2500 MHz is more than 10%.     

Hybrid perturbation scheme for wide angle circular polarisation of stacked square-ring microstrip antennas

A unique hybrid perturbation scheme is proposed for circular polarisation of stacked square-ring microstrip antennas, where both positive and negative perturbations are used. It is shown that the method broadens the angular range of circular polarisation. Measured results confirm the simulations.     

Small circular microstrip antenna with dual-frequency operation

By using a single shorting pin and a single probe feed, the dual-frequency operation of the circular microstrip antenna is demonstrated. This dual-frequency design can result in a much reduced antenna size and provide a tunable frequency ratio of ~2.55-3.83 for the two operating frequencies. Typical experimental results are presented     

Dual aperture-coupled microstrip antenna for dual or circular polarisation

A new method for radiating dual or circular polarisation with a printed circuit antenna element is described. A square microstrip patch on one substrate is coupled to a pair of microstriplines on another substrate via two orthogonal, rectangular apertures in a common ground plane. Quadrature excitation of the system results in circularly polarised radiation.     

Single-feed dual-frequency rectangular microstrip antenna with pairof step-slots

A novel dual-frequency rectangular microstrip antenna with a pair of step-slots embedded close to the nonradiating edges is proposed and experimentally studied. The two operating frequencies have the same polarisation planes and similar broadside radiation characteristics. By adjusting the step ratio of the step-slots, the frequency ratio of the two operating frequencies is tunable in the range ~1.23-1.63. Details of the antenna design and experimental results are presented and discussed     

Single-feed dual-band circularly polarised microstrip antenna

A novel technique for obtaining dual-band circular polarisation (CP) radiation of a single-feed circular microstrip antenna is proposed and demonstrated. By embedding two pairs of arc-shaped slots of proper lengths close to the boundary of a circular patch, and protruding one of the arc-shaped slots with a narrow slot, the circular microstrip antenna can perform dual-band CP radiation using a single probe feed. Details of the antenna design and experimental results are presented     

Single-feed small circularly polarised square microstrip antenna

The design of a single-feed small microstrip antenna with circular polarisation (CP) radiation is described. This design is achieved by cutting slits in the square patch and. By adjusting the lengths of the slits, the microstrip antenna can perform CP radiation with a reduced patch size at a fixed operating frequency. This design also provides a wide CP bandwidth and relaxed fabrication tolerances     

Reconfigurable microstrip antenna with polarisation diversity

A single probe-fed reconfigurable microstrip patch antenna with symmetric cross slots is proposed. By controlling four pin diodes on the patch slots, the proposed antenna has right hand circular polarisation, left hand circular polarisation or linear polarisation.     

Single-feed slotted equilateral-triangular microstrip antenna forcircular polarization

Novel designs of single-feed equilateral-triangular microstrip antennas for circular polarization (CP) are proposed and studied experimentally. It is demonstrated that by embedding a narrow slot or a cross slot of unequal slot lengths in the triangular patch, circularly polarized radiation of microstrip antennas can easily be achieved using a single probe feed. Furthermore, results show that for the design with a cross slot, the proposed antenna can perform CP radiation with a reduced antenna size at a given frequency (denoted as compact CP operation here); that is, the required antenna size is smaller for the proposed antenna for performing CP radiation as compared to a conventional circularly polarized triangular microstrip antenna at a fixed operating frequency. Details of the proposed CP designs are described, and typical experimental results are presented and discussed     

Single-feed dual-frequency rectangular microstrip antenna withsquare slot

By cutting a square slot at the centre of a rectangular microstrip patch, both compactness and dual-frequency operation can be achieved. Several designs have been implemented. From the experimental results obtained, the required antenna size using the proposed design method can be reduced by ~17% compared to that of the conventional design method using a simple patch without the slot. Typical experimental results are presented and discussed     

Single-feed circularly polarized microstrip ring antenna and arrays

An analysis is presented for a microstrip-feed proximity-coupled ring antenna and a four-element array. Interactions between the embedded microstrip feed and the radiating element(s) are rigorously included. Results demonstrate that circular polarization of both senses can be achieved with a ring antenna with proper design of two inner stubs located at angles of ±45° with respect to the feedline. Theory and experiment demonstrate an axial ratio 3-dB bandwidth of 1% and the voltage standing wave ratio (VSWR) <2 bandwidth of 6.1%. The axial ratio bandwidth is typical for a microstrip antenna with perturbations, while the VSWR bandwidth is larger than for the circular or rectangular patch with perturbations. A mutual coupling study between two elements shows that the axial ratio is less than 2 dB for interelement spacing greater than 0.55λ_eff, while the VSWR <2 for all spacings considered. A comparison between theory and experiment is provided for a 2×2 element array. The benefits of sequentially rotating the antenna elements in an array environment are presented. The axial ratio and VSWR bandwidths are both increased to 6.1% and 18% for a four-element array. A single-element antenna with two orthogonal feeds to provide both senses of polarization is demonstrated. The ring antenna is small (D/λ₀=0.325), the substrate thickness is thin (H/λ₀~0.035), and the microstrip feed produces a completely planar antenna system, which is compatible with microwave and millimeter integrated circuits (MICs), and monolithic microwave integrated circuits (MMICs)     

Single-feed triple-frequency rectangular microstrip patch antenna with pairs of spur-lines

A rectangular microstrip patch antenna with triple resonant frequencies is presented. Two pairs of spur-lines are embedded in the non-radiating edges of the patch antenna to excite extra resonant frequencies. The placement of spur-lines is made to achieve good radiation efficiency and impedance matching at all three resonant frequencies. Good agreement between the simulations and measurements is obtained.     

Broadband circularly-polarised microstrip antenna with switchable polarisation sense

A circularly-polarised microstrip antenna capable of switching polarisation sense is presented. The proposed microstrip antenna has a circular radiating patch and is excited by an open-loop microstrip line through the coupling of a ring slot in the ground plane. Two ends of the open-loop microstrip line can be taken for the input ports to excite right-hand and left-hand circular polarisations, respectively. A prototype using PIN diodes to electrically switch the input ports is implemented, and the measured results show the 3 dB axial ratio bandwidth of more than 10% can be obtained at the two polarisation senses     

Dual polarisation of microstrip reflectarray antenna

Dual polarisation of a microstrip reflectarray was demonstrated for the first time. A 16 element array of square microstrip patch antennas operating in the X-band was used to reflect the main beam 20" off broadside in both the E-plane and H-plane     

Reconfigurable microstrip antenna with pattern and polarisation diversities

A microstrip antenna with the functions of switchable pattern and polarisation is presented. The antenna is composed of a square-ring radiating patch and four shorting walls. The shorting walls are connected to each edge of the square-ring patch through one pin diode. By controlling the states of the pin diodes, the square-ring microstrip antenna can radiate two complementary patterns (conical and broadside); moreover, dual orthogonal linear polarisations are provided for the broadside radiation. These diversity functions are operated at the same frequency band. An antenna prototype has been implemented and the results obtained are given     

Circular polarisation diversity with small size microstrip antenna

The circular polarisation diversity with the square patch microstrip antenna was obtained by the implantation of the quadrature hybrid as a microstrip feed line. The small size antenna is achieved by using the aperture coupled structure. The cavity model has been used to design an aperture coupled microstrip antenna (ACMSA) and determine the length of the open microstrip stub line in order to match microstrip antenna. The MATLAB and Advanced Design Software (ADS) have been used for designing and simulating the ACMSA. There is a good agreement between the simulated and the experimental results.