Dual frequency microstrip antenna

A single-feed dual-frequency microstrip antenna is reported. It can be impedance-matched independently at the two frequencies of operation. The tested antenna has a VSWR of 1.33 at 2.32 GHz and 1.12 at 9.425 GHz. The configuration reported here can be impedance matched over a wider frequency range using standard impedance-matching techniques.     

Broadband dual frequency microstrip antenna

A new dual port microstrip antenna geometry for dual frequency operation is presented. The structure consists of the intersection of two circles of the same radius with their centres displaced by a small fraction of the wavelength. This antenna provides wide impedance bandwidth and excellent isolation between its ports. The gain of the antenna is comparable to that of a standard circular microstrip antenna operating at the same resonant frequency. A theoretical analysis for calculating the resonant frequencies of the two ports is also presented     

Dual frequency miniature microstrip antenna

A single-feed dual frequency compact microstrip antenna with a shorting pin is described. This new antenna configuration gives a large variation in frequency ratio of the two operating frequencies, without increasing the overall size of the antenna     

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.     

Modal expansion method of analysis for slot-coupled microstrip antenna

A modal field expansion technique together with the Poynting theorem are used to derive the input impedance of a slot-coupled microstrip antenna. The approach leads to easier and lower computational requirements. Predicted values of input impedance are compared with previous theoretical and experimental results.<>     

Construction of a slot-coupled planar antenna for dual polarisation

A new type of feeding technique for a dual polarisation antenna is presented. The proposed feeding system was experimentally investigated for both a single element antenna and basic planar array antenna. This antenna system demonstrated high performance in both isolation characteristics and radiation patterns     

Small slot-coupled circularly-polarised microstrip antenna withmodified cross-slot and bent tuning-stub

A novel design of small slot-coupled circularly-polarised circular microstrip antenna with a modified cross-slot cut in the patch and a bent tuning-stub aligned along the patch boundary is proposed and experimentally studied. Results show that, for fixed circular polarisation (CP) operation, the antenna proposed can have an antenna size reduction of ~80%, as compared to a regular-size CP design. The significant size reduction of the proposed antenna is due to the novel modified cross-slot cut in the patch, and CP operation is obtained using a bent tuning-stub incorporating a properly oriented coupling-slot in the ground plane of the microstrip feed line     

Slot-loaded, meandered rectangular microstrip antenna with compactdual frequency operation

A novel single-feed compact dual-frequency design is demonstrated. The proposed design consists of a rectangular patch loaded with two parallel slots close to the radiating edges and meandered with slits at the non-radiating edges. The two operating frequencies have parallel polarisation planes and, by varying the insetting slit length, the frequency ratio of the two frequencies is tunable in the range of ~1.8-2.4. In addition, with the insetting slit, the two frequencies can be greatly lowered, which results in a large antenna size reduction for fixed dual-frequency operation     

Gap-coupled microstrip array antenna for wide-band operation

The theoretical and experimental investigations carried out on a gap-coupled microstrip array antenna reveal that there is a significant improvement in VSWR and bandwidth characteristics of the gap-coupled microstrip array antenna as compared with a conventional microstrip array antenna. The input impedance and the resonant frequency of the gap-coupled patch are found to depend heavily on the gap length as well as on the dielectric constant of the substrate material.     

Slot-coupled meandered microstrip antenna for compactdual-frequency operation

By using a meandered rectangular patch and a slot-coupling feed. Compact dual-frequency operation of microstrip antennas is achieved. In this design, the two operating frequencies are mainly controlled by the patch dimensions and the insetting slit length; a large frequency ratio (>2.5) of the two operating frequencies can also be obtained. For fixed dual-frequency operation, an antenna size reduction as large as ~50% has also been obtained using the present proposed design as compared to the case using a regular rectangular patch     

Slot-loaded bow-tie microstrip antenna for dual-frequency operation

By loading a pair of narrow slots close to the radiating edges of a bow-tie microstrip antenna, dual-frequency operation can be obtained using a single probe feed. Various frequency ratios, within the range 2.0-3.0, of the two operating frequencies can be obtained by varying the flare angle of the bow-tie patch. Details of the antenna design and experimental results are presented and discussed     

Single-element rectangular microstrip antenna for dual-frequency operation

The letter describes a single-element rectangular microstrip antenna which can operate simultaneously for two different frequency bands.     

Low-profile dual-frequency circular microstrip antenna for dual ISMbands

A novel dual-frequency design of a singIe-layer, single-feed circular microstrip antenna for dual ISM bands is demonstrated. Due to the embedding of an offset open-ring slot in a circular patch, a novel dual-frequency operation with its two operating modes centred at about frequencies 2.4 and 5.2 GHz has been obtained. The two operating frequencies have similar broadside radiation patterns and same polarisation planes, and small antenna-gain variation. Details of the antenna design and experimental results for the proposed antenna are presented     

Dual band tunable microstrip patch antenna

A simple design for a dual-band microstrip antenna operating at 3 GHz is presented. The dual band operation is obtained when the antenna is loaded with a cross-line shorted with a ground plane at one end. The frequency separation is found to be sensitive to the position of the cross-line     

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     

Long backfire antenna with insular image guide feed for dual frequency operation

A long backfire antenna using an insular image waveguide feed compatible with microwave dielectric integrated circuit technology is presented. The antenna operates as a backfire component from 9.7 to 9.9 GHz and as an endfire antenna from 8.9 to 9.9 GHz, with symmetrical radiation patterns and low crosspolarisation. The important parameters of the antenna are experimentally optimised to give a maximum gain of 20 dB and 17 dB when working as a backfire and endfire antenna, respectively. This type of antenna can find extensive applications at millimetre-wave frequencies.     

A C/ka dual frequency dual Layer circularly polarized reflectarray antenna with microstrip ring elements

This paper reports a dual frequency dual layer circularly polarized reflectarray operating in the C and Ka bands. A 0.5-m right-hand circularly polarized planar reflectarray antenna is designed using microstrip ring elements of variable rotations to achieve a cophasal beam at broadside. The microstrip ring elements are more compact than the traditional reflectarray elements and can minimize blockage for the multilayer multifrequency applications. The highest efficiencies measured are 46% at 7.3 GHz and 38% at 31.75 GHz. The tested cross-polarization levels are -21 dB at 7.3 GHz and -29.2 dB at 31.75 GHz at the broadside direction. The tested results show that the designed ring element is suitable for both the single and dual layer applications with good bandwidth and circularly polarized performance.     

Dual frequency microstrip rectangular patches

A dual frequency microstrip rectangular patch antenna resonating at frequencies 520 MHz and 2.5 GHz is presented. This antenna incorporates a matching structure to improve the impedance characteristic at one resonance frequency and uses symmetrically positioned varactor diodes to control resonance at a lower frequency. The use of varactor diodes also provides the benefit of a broad tuning range at the lower resonance frequency. A tuning range of 32% at 520 MHz was measured.<>     

Compact microstrip antenna with dual-frequency operation

The characteristics of a single-feed dual-frequency compact microstrip antenna with a shorting pin are studied experimentally. Besides the compactness of the antenna, this dual-frequency design can provide a high frequency ratio of >3.0 between the two operating frequencies. Typical experimental results of the proposed antenna are presented and discussed