An annular ring coupled to a shorted patch

A novel broad-band microstrip antenna is presented. The printed configuration consists of a shorted circular patch and a concentric parasitic annular ring. Compared to a conventional microstrip patch, this ensemble is smaller in size with enhanced impedance bandwidth. Both experimental and theoretical impedance behavior and radiation characteristics of the modified patch are considered. Very good agreement between the experiment and the theory was achieved     

Broadband stacked annular ring coupled shorted circular microstripantenna

A novel microstrip antenna consisting of a stacked annular ring coupled to a shorted circular patch is presented. This new geometry offers a large impedance bandwidth, a higher gain and lower cross-polarisation levels in the H- and E-planes. Experimental results are compared with theoretical values     

A dual polarized aperture coupled circular patch antenna using a C-shaped coupling slot

The design and development of a dual linearly polarized aperture coupled circular microstrip patch antenna at C-band are presented. The antenna uses a novel configuration of symmetric and asymmetric coupling slots. Variations in isolation between orthogonal feedlines and antenna axial ratio with the position of coupling slots are studied and broadband isolation and axial ratio are achieved. The prototype antenna yields 7.6 dBi peak gain, 70/spl deg/ 3-dB beam width, 25 dB cross-polarization levels and an isolation better than 28 dB between the two ports. With an external quadrature hybrid coupler connected to the two orthogonal feedlines, the antenna yields 3-dB axial ratio bandwidth of more than 30% at 5.8 GHz.     

Stacked quasi-elliptical patch array with circular polarisation

A simple stacked subarray antenna with circular polarisation is presented. The antenna is based on a quasi-elliptical patch antenna fed with a 45deg offset microstrip line and a circular patch stacked on top of it via an air substrate. The single-element circularly polarised antenna is sequentially rotated into a four-element synchronous subarray resulting in improvement in antenna performance in terms of impedance bandwidth, gain and axial ratio. The antenna is experimentally verified and the results are reported     

U-slot circular patch antennas with L-probe feeding

Experimental results for U-slot circular patch antennas with L-probe feeding are presented. Using a foam layer of thickness ~0.1λ₀ as a supported substrate, an impedance bandwidth of 38% (SWR⩽2) and a gain of 6.8 dBi have been achieved. The far-field radiation patterns are stable across the passband     

Tunable circular patch antennas

A method to control the resonant or operating frequencies of circular patch antennas has been investigated experimentally and theoretically. It consists of the placement of passive metallic or tuning posts at approximate locations within the input region of the antenna. Comparison of measured and analytical results seems to establish the validity of a theoretical model proposed to determine the input performance of such circular patch antennas.     

Broadband patch antenna with ring slot coupling

A novel broadband linearly polarised patch antenna design is achieved using an H-shaped patch coupled to a microstrip feed line via a ring slot in the ground plane. The results indicate that a wide impedance bandwidth of 54% (2.3-3.845 GHz) can be achieved, together with a broadband gain of 6.6 dB and low levels of cross-polarisation.     

Wideband aperture coupled microstrip patch array with backlobereduction

An E-plane aperture coupled microstrip patch array antenna is presented which incorporates novel microstrip reflector elements in its design. These elements provide a significant reduction in back radiation levels over a bandwidth in excess of 20%. Design considerations for the array elements are given and radiation patterns for the microstrip elements and the total array are presented     

Compact annular-ring embedded circular patch antenna with cross-slot ground plane for circular polarisation

A compact circular patch antenna embedded in a narrow annular-ring which uses an unequal cross-slotted ground plane is presented. This new compact structure provides circular polarisation and is easily matched to 50 /spl Omega/ at the low frequency of operation. The size of the proposed antenna is reduced by over 55% compared to the conventional annular-ring CP patch antenna with a strip. The bandwidth and centre-frequency show weak dependence on the position of the feedpoint in the patch and demonstrate wider manufacturing tolerances. Good circularly polarised properties and wide bandwidth are obtained for the proposed compact antenna.     

Full-wave aperture coupled patch antenna

An aperture coupled patch antenna with a dual-lobed (cavity mode TM/sub 200/) radiation pattern is described. The antenna employs a full-wavelength long patch fed via a butterfly-shaped aperture and a stripline feed network. This configuration provides high patch to feed network coupling and reduced back radiation. Measured return loss and pattern data are presented with proposals for several potential applications of this element.<>     

Slot coupled dual-mode patch filters

A configuration for the realisation of extracted pole planar elliptic function filters is proposed. The new filter configuration consists of chamfered patches in a microstrip assembly which are coupled by a slot. The two degenerated modes that can exist in a two-dimensional square resonator are slightly shifted in resonance frequency     

A novel wide-band circular patch antenna

In order to overcome the narrow-bandwidth of the patch antenna, one kind of configuration which can widen the bandwidth significantly is discussed in this letter. Analyzed by the equivalent-circuits method and simulated by HFSS, a rule derived from simulated results that can aid to design the microstrip antennas is found. Finally, the structure parameters are optimized out, which reaches 44.67% impedance bandwidth. Furthermore, this kind of configuration can also be applied to the multi-layer patch antenna.     

Radiation modes in circular patch antennas

We have formulated exact solutions of the normal modes in the microstrip patch antenna possessing circular geometry. The theory makes use of a new Green's function in conjunction with current potential analysis. The calculations demonstrate that the magnetic wall confinement boundary conditions as formulated in past theories hold approximately true if the surface wave loss is minimal compared to other losses: dielectric loss, conductor loss, and radiation loss. For practical path antennas the normal modes are not confined locally near the microstrip patch. Rather, they are composed of propagation surface waves which extend far beyond the region containing the patch antenna. We term these normal modes as leaky modes, since they resemble the leaky modes found in dielectric image guides. Measurements by us of the radiation mode frequencies and the intrinsic Q-values of the microstrip patch antennas compared very well with theory     

Semiconductor circular ring lasers fabricated with the cryo-etchingtechnique

GaAs-AlGaAs multiple quantum well semiconductor circular ring lasers with a σ shape were fabricated by using the deep UV laser-assisted cryo-etching technique. Most of the fabricated lasers had external quantum efficiencies of more than 18% which mere higher than similar devices previously reported. The modal spacing observed from the resonance spectrum near threshold was always several times that corresponding to the circular oscillation of the ring cavity. The observed modal spacing was quite consistent with the theoretical result based on a coupled-cavity model     

Tri-band frequency selective surface with circular ring elements

Theoretical analysis, physical reasonings, and experimental verifications are presented for a frequency selective surface with circular ring elements. Both double-screen and single-screen designs are generated for a tri-band system that reflects the X-band signal while transmitting through the S- and Ku-band signals. In these designs, the dielectric loading effect is used to reduce ring size and element spacing and thus avoid the grating lobe problem. The circular ring element is very insensitive to a large variation of the RF incident angle     

A systematic design method to obtain broadband characteristics for singly-fed electromagnetically coupled patch antennas for circular polarization

We present a systematic, empirical design technique to obtain optimum broadband impedance, axial-ratio (AR) and gain bandwidths for a singly-fed electromagnetically coupled patch antenna for circular polarization. Our investigation has also revealed tradeoffs amongst obtainable AR, impedance bandwidth and AR bandwidth. Using two design examples at different frequency bands and for different senses of circular polarization, we have demonstrated the effectiveness of the proposed knowledge-based tuning method. We have obtained at C-band measured values of impedance bandwidth (VSWR/spl les/2) equal to 43%, 3-dB AR bandwidth of 8%, AR of less than 0.3 dB and a mean gain level of 7 dB. For the Ku-band element, a 40% impedance bandwidth and a 17.3% of 3-dB AR bandwidth have been obtained with a peak gain of 7.2 dBic.     

Multifunctional aperture coupled stack patch antenna

A multifunctional aperture coupled stacked patch antenna is presented that operates at dual frequency bands. At the lower frequency band, the antenna exhibits a 2:1 VSWR bandwidth of 20%, and at the higher frequency band, it behaves like a conventional narrowband patch antenna with a 2:1 VSWR bandwidth of 3%. Measured VSWR and far-field radiation patterns as well as numerical predictions are presented. A proper choice of the patch dimensions has been found critical to achieve this multifunctional performance.<>     

单频圆形微带贴片天线设计

基于微带贴片天线在无线引信中的应用,设计了一种中心频率为7.2 GHz的同轴馈电圆形微带天线,该天线介质基片相对介电常数为εr=4.4,回波损耗小于-20 d B,天线增益大于5 d B。根据微带天线原理,通过HFSS软件设计的天线,实验结果表明:天线谐振频率、回波损耗等性能参数符合设计要求。