The results from the equivalent circuits and simulation show acceptable agreement. The return loss and radiation patterns are shown in Figure 10. The antenna bandwidth for the proposed magneto-dielectric substrate is about six times higher than that of the dielectric substrate. Cite this article as: Ali, M. This paper presents a flexible wearable antenna on fabrics such as cotton, jeans and silk. Note, however, that the circuit presented in Figure 1. For these measurements, the real part represents the input resistance and the imaginary part represents the input reactance, with a positive value being inductive reactance and a negative value being capacitive reactance.
The second antenna, the half-mode cavity, originates from a half-mode substrate-integrated cavity, where an open aperture placed on the substrate's symmetry plane enables to only use one-half of the entire cavity. With microstrip feeding, it is also a relatively simple task to implement either linear or circular polarization excitation of the antenna. Two other interesting compact structures for the implementation of wearable textile patch antennas operating at 2. As a result, large negative differential conductance is expected against small peak current density. In this paper we present the comparative performance analysis of 4 different shaped antennas.
A rectangular cavity is formed inside the antenna substrate, by using eyelets as metallized holes, with an appropriate spacing distance between each other. The authors first developed an analytical analysis of both structures. Tatsuo Itoh, in , 2005 11. Alternatively, matched bandwidth of the antenna can be increased by making the antenna substrate electrically thicker, effectively lowering the Q-factor of the antenna cavity for increased bandwidth. Effects of bending were also verified by simulations, resulting in a very small increase of resonance frequency for a bending radius of 10 cm, which does not compromise the overall performance in the operation band. The structure consists of a cavity-backed slot antenna on a flexible protective foam substrate, with electrotextiles Flectron metallization on both sides.
This model provides a reasonable estimate for the resonant frequency and a fairly accurate estimate of the input impedance close to resonance. Top View of Microstrip-Fed Patch Antenna Returning to Figure 11. A simple and intuitive technique for modeling this antenna is the transmission line model. The measured results agree well with the simulated results. Measured gain patterns also remain almost unchanged in the on-body case, with respect to the free-space situation, with the maximum value being about 6 dBi in the broadside direction, which is more than sufficient to establish a reliable off-body communication link. In a patch antenna, most of the propagation is above the ground plane and can have high directional gain. Such a kind of patch antenna answers to important requirements in off-body communications, such as suppression of undesired surface waves and a high level of shielding from the human body, even with a very small ground plane, high directivity, and front-to-back ratio, as well as performance stability.
Thus, it can be concluded that a radiating patch can be modeled by two slots separated by a transmission line. The simplest way for estimating this is the transmission line model for the patch antenna. This proposed antenna model and progressing the investigation of an inset fed wideband circular slotted patch antenna is suitable for 5. In particular, the authors showed, through both measurements and simulations, how the proximity of a human arm over which the antenna was bent affects its performance by producing a resonance frequency shift. Microstrip-fed patches have very narrow bandwidths, almost invariably less than 5%.
This causes radiation at the two edges of the antenna, as shown by the fringing fields in the diagram. The InGaAs and InAlAs layers are lattice-matched to InP substrates. The antenna is also low profile and low cost, has good conformability, and has ease of manufacturing. A parallel resistance is put between the bias supply lines in order to prevent parasitic oscillation due to return pass of the bias supply lines. This behavior may have significant applications to polarization-specific antennas and may be useful for improving isolation between neighboring antennas on a shared platform.
With reference to Figure 3. The antenna, shown in Fig. A simulation model of this design is shown in Fig. The bandwidth, however, does provide a useful starting point as well as useful insight into the operation of the antenna. Note that there are many other simple models that also provide a first-order estimate of the input impedance. The antenna gain and the return loss of the suggested antenna at 0. In this case, the antenna is modeled as two radiating slots of width Δ l oc and length a separated by a microstrip transmission line with dimensions corresponding to the dimensions of the patch antenna.
As shown in Figure 10. A circularly shaped slot has been chosen to be etched on diminutive square patch 4. The fundamental resonance of the cavity formed by the microstrip patch antenna will occur at the frequency where the total effective length of the patch antenna, b + 2Δ l oc, is equal to one-half a guided wavelength in the microstrip cavity. In this case, higher resonances of the antenna will be determined by circular harmonics Bessel functions and can be designed to occur away from circuit harmonics. Note that the feeding can be placed at one end of the antenna or at some point a distance x inside the patch, either by the use of an inset feed or a coaxial probe. The shapes taken into consider are E, T, H and F. The efficiency in this case for a dielectric loss tangent of 0.