Aperture-coupled small microstrip antenna

An aperture-coupled small microstrip antenna is described. The antenna is formed by short-circuiting a microstrip radiating element with a shorting pin to the ground plane and exciting the element with a microstrip feedline through an electrically small aperture. Two principal advantages of this design are that the size of the antenna is significantly reduced and that it is relatively easy to fabricate the antenna. Experimental data for the return loss and the radiation pattern of the antenna are presented to validate the design     

An aperture coupled microstrip antenna with a proximity feed on a perpendicular substrate

A new feeding configuration for microstrip antennas is described, where separate substrates are used for the radiating patch element and the microstrip feedline. The substrates are joined perpendicular to each other, and the patch is excited through an aperture in the antenna substrate ground plane by proximity coupling to the microstrip feedline, This design thus has a number of advantages over other feeding configurations, particularly when used in an integrated phased array application. These features, as well as the measured results from two experimental models, are described.     

Aperture-coupled microstrip line leaky wave antenna with broadsidemainbeam

A microstrip first higher order leaky wave antenna (LWA), centre-fed by an aperture-coupled microstrip with a broadside mainbeam, is presented. The measured bandwidth (23% for VSWR<2:1) is in agreement with the leaky radiation band predicted. The experimental gain patterns, compared with those of a patch antenna fed by the same type of structure, reveal the difference between these two kinds of antenna. With increasing frequency, the radiation field of the LWA spreads into the H-plane, forming a flatter broadside pattern, which can be applied to long rectangular area communication     

Circularly polarized microstrip antenna with a single feed

A novel circularly polarized (CP) microstrip antenna with a single coaxial feed is introduced. The antenna consists of two layers, each radiating fields which at the zenith are perpendicular to each other with 90° phase difference. The CP bandwidth is substantially higher than that of the previously reported CP microstrip antennas with two nearly degenerate modes. In principle, a perfect CP radiation is feasible without the input impedance mismatch. The CP design procedure is independent of the feed location     

Planar circularly polarized microstrip antenna with a single feed

A novel circularly polarized (CP) microstrip antenna is introduced. The antenna is fed with a single coaxial probe and the structure is planar. The CP bandwidth is much larger than available single-probe microstrip antennas and the CP radiation quality is excellent over the entire upper hemisphere     

Aperture-coupled dielectric resonator antenna with a perpendicularfeed

The aperture-coupled dielectric resonator antenna with perpendicular feed is investigated experimentally. The return loss, radiation pattern, and antenna gain of the new configurations are given and discussed     

新型带扇形馈源的宽带缝隙天线

介绍了一种新型的采用扇形微带馈源的宽带缝隙天线,给出了反射损失曲线和辐射方向图。该天线采用稍高的相对介电常数（εr=4．3）和薄基片（h=1．1mm）,获得了约106％的阻抗带宽（S11≤-10dB）,频率范围是1．65GHz～5．38GHz。采用电磁仿真软件Ansoft HFSS8．0^TM对几个天线尺寸的影响进行了仿真与讨论,并与文献[6]的结果相比较,验证了设计的有效性,同时也证明了结果的可靠性。     

Slot-coupled microstrip antenna with a triplate line feed whereparallel-plate mode is suppressed

In a slot-coupled microstrip antenna with a triplate line feed, the parallel-plate mode is excited by the slot, resulting in a decrease of radiation efficiency. The authors present a technique for suppressing the parallel-plate mode in this type of the antenna. Measured results confirm the effective performance of the proposed method     

Slot-coupled dielectric resonator antenna using a proximity feed ona perpendicular substrate

The slot-coupled dielectric resonator antenna with a proximity feed on a perpendicular substrate is investigated experimentally. The return loss, radiation pattern, and antenna gain of the new configuration are measured and discussed     

Fractal boundary circularly polarised single feed microstrip antenna

A Koch fractal boundary circularly polarised single feed microstrip antenna is presented. The proposed antenna gives very good circular polarisation with axial ratio close to 0 dB at the centre frequency of 2510 MHz, 3 db axial ratio bandwidth of about 1.6% and impedance bandwidth of 6.2%. Tt is established that it is easy to obtain circular polarisation using the fractal curve as the boundary. The antenna provides about 6 dB gain over the frequency band of operation.     

Circularly polarised microstrip antenna array using proximitycoupled feed

A 2×2 circularly polarised (CP) microstrip antenna array using a proximity coupled feed and sequential rotation is described. As compared with a previously presented single-element circularly polarised microstrip antenna with a cross-slot, the new array achieves a much wider impedance bandwidth of 11.18% and has an axial ratio bandwidth of 4.1%. The return loss, radiation patterns and axial ratio of the antenna array were measured and are presented     

Aperture-coupled antenna with switchable polarisation and frequency agility

The design of an aperture-coupled microstrip antenna with switchable polarisation and frequency agility is studied. Switching between two orthogonal linear polarisations (LPs) is realised by mounting two switching pin diodes on the antenna. To achieve multi-operating frequency (frequency agility) on one of the LPs, a voltage-controlled varactor diode is loaded between the top-loaded square patch and the ground plane. From the measured results, a good cross-polarisation level is observed when operated in both linear states at around 2 GHz.     

Aperture-coupled patch antenna on UC-PBG substrate

The recently developed uniplanar compact photonic bandgap (UC-PBG) substrate is successfully used to reduce surface-wave losses for an aperture-coupled fed patch antenna on a thick high dielectric-constant substrate. The surface-wave dispersion diagram of the UC-PBG substrate has been numerically computed for two different substrate thickness (25 and 50 mil) and found to have a complete stopband in the frequency range of 10.9-13.5 and 11.4-12.8 GHz, respectively. The thicker substrate is then used to enhance broadside gain of a patch antenna working in the stopband at 12 GHz. Computed results and measured data show that, due to effective surface-wave suppression, the antenna mounted on the UC-PBG substrate has over 3-dB higher gain in the broadside direction than the same antenna etched on a grounded dielectric slab with same thickness and dielectric constant. Cross-polarization level remains 13 dB down the co-polar component level for both E- and H-planes     

CPW feed circularly polarised microstrip antenna using asymmetric coupling slot

Design of a coplanar waveguide (CPW) feed square microstrip antenna with circular polarisation (CP) radiation is described. This CP design is achieved by using an asymmetric inductively coupling slot in the ground plane of the CPW feed line. Results show that the proposed antenna can have a CP bandwidth of 2.4%, whereas a simple inclined coupling slot case has 1.6% CP bandwidth at a fixed square patch size. Typical experimental results are presented and discussed     

A twin slot antenna on a layered substrate coupled to a microstrip feed line

A method is described for calculating the input impedance as seen by the detector for a twin slot antenna structure. This technique is then used to analyze several twin slot antenna configurations, leading to improved performance.     

Aperture-coupled, differentially-fed planar inverted F antenna

A differentially-fed single aperture is used to excite an unsymmetrical antenna contactlessly. The current maximum below the aperture is generated by an odd-mode signal, rather than an open-circuit stub. Simulated and measured 0.9 GHz results, with a planar inverted F antenna, suggest potential applications in mobile communication systems.     

A novel single feed frequency and polarization reconfigurable microstrip patch antenna

In this paper, a novel single feed frequency and polarization reconfigurable microstrip patch antenna is presented. This antenna mainly comprises of a corner truncated square patch with a rectangular ring slot, eight PIN diodes and six conductive pads. Four PIN diodes are placed symmetrically in the rectangular ring slot to bridge the gap and to switch the frequency between WLAN bands resonating at 5.2G Hz and 5.8G Hz. Four PIN diodes connect the corner truncated square patch to parasitic triangular conductors. PIN diodes are used to switch the polarization between linear, right hand circular and left hand circular at each frequency. When compared to conventional patch, the proposed design provides a size reduction of 12% at 5.2G Hz, and 30% at 5.8G Hz. The simulated reflection coefficient and radiation patterns are presented and compared with the experimental data. This antenna finds applications for modern wireless communication system.     

Analysis of a suspended patch antenna excited by an electromagnetically coupled inverted microstrip feed

A suspended patch antenna electromagnetically excited by an inverted microstrip line has been studied based on a full-wave transmission line analysis in conjunction with a microwave network theory. The input impedance calculated has been compared with measured data.     

An annular-ring microstrip antenna fed by a co-planar feed circuitfor mobile satellite communication use

A new configuration of circularly polarized annular-ring microstrip antenna (ARMSA) fed by a branch-line hybrid coupler placed at the inner part of the ARMSA and its design method using an equivalent circuit are presented. Since the ARMSA has a narrow bandwidth and high-input impedance, a parasitic element placed above the ARMSA is employed for not only obtaining a broadband characteristic, but decreasing the input impedance down to 50 Ω. A hybrid coupler to generate circular polarization, therefore, can be connected to the co-planar space of the ARMSA directly without a large-size matching circuit and a very low profile and simple structure can be achieved. The ARMSA is excited at the TM₂₁ mode to produce a conical pattern, which has a high gain in a low-elevation angle for mobile satellite communications. An effective design method using the equivalent circuit is indicated and, as a result, it is obvious that a broadband characteristic is obtained when each resonant frequency of the ARMSA and parasitic element is identical. Experimental results in the L-band showed satisfactory characteristics for vehicle antennas     

Parallel-series feed network with improved G/T performance for high-gain microstrip antenna arrays

A 16 x 8 microstrip antenna array with 28 dB of gain at 18 GHz using a parallel-series feed with reduced conductor traces is presented. The feed network connects antenna elements with about 50% reduction in conductor traces compared to conventional arrays with equal numbers of radiating elements. It also enhances the gain-bandwidth performance of the array and maintains a broadside radiation pattern in a wider frequency band. The full-wave simulation results are verified by means of measurements that demonstrate a relative gain-bandwidth of 4.4% with less than 1 dB of gain ripple.