Search

This paper presents a slotline open-loop resonators based frequency reconfigurable antenna with autonomous switching of frequency bands. The dual-port slot antenna is designed to operate at 2.1 GHz when excited at port-1, and when port-2 is excited, the antenna can be reconfigured to operate at 2.85 GHz and 5.52 GHz, respectively. Port-1 is used to receive the control signal, which is converted to a DC signal using a rectifier. The rectified control signal is used to switch the operating frequency bands of the port-2. The proposed antenna configuration gives the flexibility of remote/wireless control of the operating frequency. The antenna prototype is fabricated and measured for observing the frequency switching at port-2. The measured results show that the antenna has been effectively switched from lower band frequency (2.8 GHz) to upper band frequency (5.41 GHz) when the PIN diode is ON. The proposed antenna in its final configuration can be potentially suitable for transmitter reconfigurable antenna without the need for external DC bias voltage.

This paper presents a novel design of a low profile circularly polarized (CP) metasurface (MTS) antenna with in-band radar cross-section (RCS) reduction property. The MTS is loaded as a superstrate on slot antenna and it can be viewed as a polarization-dependent MTS (PDMTS). The rectangular patch-based PDMTS is analyzed using characteristic mode analysis to find two orthogonal degenerate modes, which produces CP waves. Linearly polarized slot antenna is used to excite the PDMTS. The performance of PDMTS loaded slot antenna is analyzed numerically using full-wave analysis method. The PDMTS CP antenna is fabricated and its performance is tested experimentally. The proposed antenna has a compact structure and it has an overall size of $0.52{\lambda _0}\times 0.52{\lambda _0} \times 0.078{\lambda _0}$ (where ${\lambda _0}$ is the free space wavelength). The measured results show that the PDMTS antenna achieves $-10\,{\rm dB}$ impedance bandwidth of 29.41$\%$, 3-dB axial ratio bandwidth of 9.05$\%$, broadside gain of 6.34 dB, and monostatic RCS reduction of $-30.2\,{\rm dBsm}$ at the resonant frequency of 5.86 GHz. The simulated results are in well agreement with the measured results and it is well suited for C-band Radar and Satellite communication.

This paper presents the design of a coplanar waveguide (CPW)-fed single-layer wideband circularly polarized (CP) planar slot antenna backed by a frequency selective surface (FSS). The planar slot antenna is fed with a stub-loaded modified CPW feed line to tune and optimize the impedance bandwidth. The corners of the square slot antenna are perturbed to produce two orthogonal degenerate modes required for a wideband CP operation. The FSS layer is placed under the slot antenna to increase the gain and axial ratio bandwidth. The measured results of the proposed antenna provide an impedance bandwidth of 63.22% and an axial ratio bandwidth of 31.14% with a peak gain of 4.87 dB. The proposed antenna has a simple geometry, a wide CP bandwidth, and a good gain.

In this letter, a novel high-gain circularly polarized (CP) antenna based on the zero-index metamaterial (ZIM) is presented. A square ring with two asymmetrical splits is used as a unit cell to achieve high gain and circular polarization. The 9 × 9 periodic array unit cells act as an aperture efficient focusing metasurface lens and polarization converter for a primary source antenna. The focusing effect of the ZIM enhances the gain of the microstrip patch antenna placed above it by an amount of 5–6 dB. Also, the ZIM converts the linearly polarized wave emitted by the patch antenna into circularly polarized waves. The circular polarization is achieved by optimizing the two split gaps on the ring of the unit cell, which gives two orthogonal polarizations with the required phase. The proposed design is fabricated and verified experimentally. The prototype has measured impedance bandwidth from 7.04 to 7.68 GHz. The 3 dB axial ratio is achieved from 7.11 to 7.56 GHz, with a peak gain of 12.31 dBic at 7.45 GHz. The gain of around 11.5 dBic is achieved over the entire CP bandwidth with a good cross-polarization level.

A transmission line (TL) loaded, compact, ultrawideband (UWB) square slot antenna is proposed in this letter. The square slot is a microstrip line fed and loaded with an array of periodically perturbed TLs to achieve a UWB response from 2.1 to 11.5 GHz. The slot is designed to resonate at 2.6 GHz. The TLs are dispersion engineered to resonate at several frequencies so as to provide a wideband response. Loading of the engineered TLs on the square slot produced multiple resonances without affecting the fundamental mode of the slot antenna. The proposed antenna design is analyzed using dispersion relations and equivalent circuits. The proposed antenna is fabricated on an RT/Duroid 5880 substrate with a size of 50 × 50 × 1.52 mm3. The antenna performance metrics, such as impedance bandwidth, gain, and efficiency, are experimentally verified. Good agreement is obtained between simulated and measured results.

A simple copper strip array loaded multiband square slot antenna with microstrip line feed is proposed in this paper. The slot antenna is designed to radiate at 2.28 GHz. The slot is loaded with a uniform array of rectangular copper strips to produce other resonances at 2.2 GHz, 3.4 GHz, 4.6 GHz, 5.4 GHz, 6.6 GHz. The proposed antenna is modeled and simulated using HFSS. The antenna prototypes are fabricated and tested. Good agreement is obtained between the measured and simulated results. The surface current distributions at the various resonant frequencies are simulated. The principle of operation is explained based on the distributions obtained and using analytic equations. An equivalent circuit model is also studied. Impedance bandwidths of 500 MHz, 300 MHz, 600 MHz, 400 MHz, 600 MHz and a gain of above 3 dB is obtained at the five resonant frequencies.

A compact multiband circularly polarized slot antenna is proposed here. An F-shaped microstrip feedline is used to excite the square slot antenna loaded with a U-shaped strip and a split ring resonator (SRR) to generate three circularly polarized bands at 1.5 GHz, 2.75 GHz and 3.16 GHz. A meandered slot is used in the feedline and the U-strip to improve the axial ratio bandwidth (ARBW). The meandered feedline excites the slot to produce resonance at 2.5 GHz. This resonance along with that of the F-shaped feed, loaded SRR and U-strip combine to give rise to three circularly polarized bands which can be tuned depending on the feed, SRR and U-strip dimensions. The orientation of the F-shaped feed decides the sense of polarization of the three circularly polarized bands of the proposed antenna. The proposed antenna is fabricated on a substrate of FR4 material with dimensions 50 x 50 x 1.56 mm3. The antenna is prototyped and measured in terms of impedance bandwidth, ARBW, gain and efficiency. The simulated and measured results show reasonably good agreement.

In this communication, a simple and compact multiband circularly polarized (CP) slot antenna loaded with metallic strips and a split-ring resonator (SRR) is proposed. The multiband operation is obtained via exciting the SRR and copper strips by the microstrip-fed square slot antenna. The SRR resonates at 1.83 GHz, while the strips and the slot antenna provide resonances at 2.5 and 3.1 GHz. Resonant modes of loaded SRR and strips combined with the fundamental mode of the slot produce CP waves at the resonance frequencies of the proposed antenna. The proposed antenna allows for independent tuning of different bands via the use of the tilted strips and the SRR. Also, the sense of polarization at the resonance frequencies can be controlled by changing the orientation of the strips and the SRR with respect to the slot. The proposed antenna is fabricated on an FR-4 substrate of dimension $50 \times 50 \times 1.56$ mm3. Antenna performances in terms of 10 dB return loss bandwidth, 3 dB axial ratio bandwidth, gain, and efficiency are validated experimentally and are in a good agreement with the simulated results.

A Goubau-line leaky-wave antenna (LWA) with a large scanning angle is presented in this letter. In contrast to the conventional Goubau-line leaky wave with a small scanning angle range, this letter employed a periodically bending Goubau line, which not only brings in a periodic perturbation for leaky-wave radiation, but also enhances the scanning range due to the increased delay for each line element. The simulation and experimental results show that the proposed LWA provides $90\%$ radiation efficiency and 7–10 dBi radiation gain from backfire to endfire through broadside as frequency changes. The proposed antenna features good radiation performance and has a compact and low-profile configuration.

In this paper, an aperture efficient wideband high-gain patch antenna is designed using a novel multilayer-based metamaterial structure combined with a reactive impedance surface (RIS)-backed patch antenna. The metamaterial unit cell is a two-layer structure which is stacked one after other to form the overall unit cell. The microscopic behavior of the proposed unit cell has been investigated. This unit cell gives low refractive index over a wide bandwidth with a negligible loss. An RIS-backed patch antenna has been designed in the required frequency band to feed the multilayer zero-index metamaterial medium. The introduction of this surface is to provide unidirectional radiation over a wideband in the zero refractive index region. The proposed antenna gives a 14% fractional bandwidth over the $C$ - and $X$ -bands. The proposed antenna enhances the peak gain of the conventional patch antenna by an amount of 8.5 dB at 8 GHz. Finally, the antenna has been fabricated and its performance is verified experimentally.

A compact tri-band slot antenna with independent tuning capability of its resonant frequencies is proposed in this article. A microstrip line fed square slot is loaded with split ring resonators (SRR) to obtain multiband characteristics. The slot is designed to resonate at 2.6 GHz. Two SRRs with single and multiple splits are loaded with the slot, which provide additional resonances at 4.3 and 4.7 GHz, respectively. Parametric analysis of the antenna shows that its resonance frequencies are controlled independently. The proposed antenna is fabricated on an FR4 substrate with a size of 60 × 60 × 1.56 mm2. The proposed design offers stable omnidirectional patterns and >3.8 dBi at all the resonating frequency bands.

A wideband dual polarized bowtie antenna for 5G applications is presented. The dual polarization is achieved by using two different bow-tie antenna elements placed in orthogonal orientation. The design consists of rectangular slots on the two arms of bow-tie antennas which enhances the port to port isolation. The unidirectional radiation pattern is obtained by placing a perfect electric conductor (PEC) ground plane at λ/4 distance. The radiating elements are designed to operate at 3.5 GHz. Measured results of the proposed dual polarized bow-tie antenna exhibit a bandwidth of 42.85% (3.1 – 4.6 GHz) and 11.4% (3.3 – 3.7 GHz) for a VSWR of < 2 and 1.5 respectively. An isolation of 28dB between the two ports and an average gain of 8.4 dB is measured for both the polarizations.

In this paper, a compact tri-band split ring resonator (SRR) loaded slot antenna is proposed which offers independent frequency tunability for operation at WLAN and WiMAX bands. The microstrip fed slot antenna is loaded with a modified SRR to obtain the triband resonance. The compactness is achieved by using an open slot antenna. The slot is designed to resonate at 2.4 GHz, which combines with the resonance obtained due to a fictitious short circuit produced at a certain point along the slot. This leads to the wideband property at the first band. The second and third resonances are obtained at 7.5 GHz and 9.3 GHz. The resonances can be independently controlled by changing the slot and SRR dimensions.

In this paper, a novel compact slot antenna suitable for penta-band applications is proposed. The different resonances are obtained by loading the slot on the top layer with an array of copper strips of equal length and with a Split Ring Resonator (SRR) at the bottom layer. The antenna prototype is fabricated and measured. The simulated and measured results are in good agreement. The antenna is found to resonate at frequencies of 1.51 GHz, 2.35 GHz, 2.9 GHz, 3.66 GHz and 5.6 GHz. Also, a gain higher that 2.4 dBi and a bandwidth of at least 80MHz are obtained for all the bands.

This letter presents a polarization-reconfigurable compact slot antenna with reduced radar cross section (RCS) using an asymmetric cross-shaped metasurface (MS). The proposed MS can reconfigure the polarization of the slot antenna between right-hand circular polarization (RHCP), left-hand circular polarization (LHCP), and linear polarization (LP) by rotating it with respect to the center of the slot antenna. In addition, the MS reduces the RCS of the slot antenna significantly in all polarization states. The cross-slot MS is placed just over the planar slot antenna without any air gap. The simulated monostatic RCS of $- $ 19.5 dBsm is observed at 4.4 GHz for LHCP and RHCP cases and $- $ 17.0 dBsm for LP mode of operation. Antenna performance in terms of its input matching, far-field parameters, monostatic RCS, and axial ratio are measured at its three polarization states, which are in agreement with simulated results.

In this paper, spoof surface plasmon polariton (SSPPs) and substrate integrated waveguide (SIW) based bandpass filter is proposed. The metal strip on the top of the substrate is composed of periodic slots which supports surface wave mode of SPP within the closed substrate integrated waveguide. The dispersion relation of the proposed structure shows that it has both low-pass feature of SSP and the high-pass feature of SIW, and hence the combination of these two features leads to a bandpass filter (BPF). The results show that the passband is from 11.5–19 GHz with relative bandwidth of 49%. Bandwidth can be controlled by properly adjusting the parameters of the design. The proposed design features a compact size and easy fabrication, due to the integration of SPP in a closed SIW.

A compact square shaped microstrip triband slot antenna is proposed. Two Split Ring Resonators (SRR) of the same configuration are loaded at one edge of the slot in a back to back orientation. The other edge of the slot is displaced with two 180° rotated SRR's with multiple slits. The additional bands are obtained from the resonance properties of the loaded SRR's. The antenna is simulated and measured. The resonance frequencies obtained are 2.7 GHz, 4.3 GHz and 4.7 GHz. A minimum bandwidth of 130 MHz is achieved.

This paper proposes a Split Ring Resonator (SRR) loaded quad band microstrip slot antenna designed to operate at 2.42 GHz, 4.33 GHz, 8.46 GHz and 10.9 GHz. The additional resonant bands are generated by loading the square slot antenna with two pairs of SRR structures on either side of the feed line. The bands centered at 8.46 GHz and 10.9 GHz are found to exhibit wideband and circular polarization properties respectively. The resonance band at 8.46 GHz provides a wide bandwidth of 2.43 GHz. One pair of the loaded SRR structure consists of two spiral shaped connected SRR's. The excitation of these structures gives rise to a circularly polarized band at 10.9 GHz with 3-dB axial ratio bandwidth of 390 MHz. Maximum gains of 3.82 dB, 3.95 dB, 7.5 dB and 4.2 dB are obtained at the four resonant frequencies, respectively. A minimum bandwidth of 270MHz is observed for all the bands of operation.

A dual-band circularly polarized (CP) microstrip line fed slot antenna using a set of split ring resonators (SRRs) is proposed in this communication. Outer ring connected SRRs are placed on the back side of the slot to create the CP upper band. Diagonally opposite corners of the slot are truncated, which together with the SRRs give CP response in the lower band. The proposed dual-band CP antenna provides design flexibility to control the resonance frequency and sense of polarization at the dual bands, independently. The proposed antenna is designed to operate at 3.1 and 4.7 GHz, which is fabricated and tested. The experimental results show the −10-dB impedance bandwidths of 400 MHz in both the bands and the 3-dB axial ratio bandwidth of 3.1% (from 3.05 to 3.15 GHz) and 4.2% (from 4.65 to 4.85 GHz) in lower and upper bands, respectively. Finally, a metallic cavity is used with the antenna to achieve a unidirectional radiation pattern with front-to-back ratio of more than 15 dB without affecting the impedance bandwidth and CP performance of the antenna.

A compact multi-band antenna using a zeroth order resonator (ZOR) loaded with a split ring resonator (SRR) and modified ground plane is proposed in this paper. The antenna resonates at 2.8 GHz, 4.3 GHz and 5.8 GHz. The antenna has a compact size of only 28.3 × 24 × 1.524 mm3. The ZOR antenna resonates at 2.8 GHz and the loading of SRR on the back side of the antenna produces the resonance at 4.3 GHz without affecting the ZOR mode. The modified ground plane provides an additional band at 5.8 GHz. The proposed antenna is simulated, fabricated and tested. The measured −10 dB impedance band width of 300 MHz, 350 MHz and 450 MHz is observed in the respective bands. Omni-directional radiation patterns are obtained at all the three bands.

A frequency re-configurable dual band dual polarized antenna is proposed. This consists of a rectangular feed patch layer and two MS layers of same thickness. MS layers are made of rectangular loop based unit cells periodically placed in both X and Y direction. The total profile of the antenna is 0.07 λ0 only. Simulation result shows that the operating frequency of the antenna can be changed by physically rotating both the MS layers with respect to the centre of the patch antenna. As the MS is rotated the excitation and the polarization with the electric field of the patch to the MS layers change which changes the effective permittivity of the whole substrate and hence the frequency of the operation also changes. Measured results are well matched with the simulation results. At all the frequencies antenna has peak gain of more than 5.5 dB and the minimum efficiency is more than 89%.

A technique to tilt the beam to the specific direction and widening the beam width of a dipole antenna using controlling the position of via in electromagnetic band gap (EBG) structures has been presented in this paper. In addition to the low profile structure, the proposed method tilts the beam in either H-plane or E-plane of the dipole. The tilt angle or beam width of the dipole antenna can be easily determined for fixed beam direction by fixing the EBG via location from the centre of the EBG. The maximum tilt angle of 34° and 29° is achieved in E-plane and H-plane respectively. A wide beam width of 153° is obtained for the wide beam antenna.

A reduced profile directional and high gain slot antenna loaded with Electromagnetic Band Gap (EBG) cavity and anisotropic negative permeability medium (NPM) is proposed which is investigated numerically as well as experimentally. Measured result shows a good agreement with the simulation result. Bandwidth of the proposed antenna extends from 3.4 GHz–4.1 GHz (Fractional Bandwidth (FBW) of 19%). Significant improvement in gain about 7 dB is achieved as compared to the conventional slot antenna with E and H plane beam-width of 35.30 and 36.80, respectively.

In this paper, a reconfigurable antenna utilizing the property of negative permeability of split ring resonators is proposed for band notched UWB and narrow band applications. The proposed design yield the resonant frequency of the narrow band operation and notch frequency of UWB operation coinciding at 5.8 GHz frequency. The proposed antenna is simulated and measured. Radiation efficiency of 80% and 50% is observed for the UWB and the narrow band operation, respectively.

In this paper a novel circular polarized/dual band dual polarized antenna has been proposed, which is validated experimentally using the meta-surface. First a 450 rotated rectangular loop based meta-surface is excited with a patch radiator to obtain the dual band dual polarized operation. Thereafter another same meta-surface is loaded on top of it to merge the two dual polarized band to obtain circular polarization. Appropriate rotation of the top meta-surface ensures maximum coupling with the X directed electric field from the bottom MS. Impedance bandwidth for dual band dual polarized operation is from 5GHz–5.28 GHz and from 5.6 GHz–5.75 GHz. For circular polarization response, impedance band width is from 4.8 GHz–5.77 GHz (Fractional Bandwidth of 19%). and 3 dB axial ratio is from 5.15 GHz–5.76 GHz. Measured gain of the antenna is 7.4 dB.