Gain Optimization of Low-Profile Textile Antennas Using CMA and Active Mode Subtraction Method

Abstract

This paper presents an active mode subtraction method based on the characteristic mode analysis to estimate the forward directivity based on the difference in modal significance curves. This made the optimization of the antenna gain in the design process to be more efficient. To the best of the authors' knowledge, such method is innovative and proposed in literature for the first time. This method is derived on the basis that the total radiated field of the antenna, and consequently, the directivity is mainly contributed by the excited dominant modes. To demonstrate its effectiveness, three compact, planar, and wearable antennas with increasing complexity will be designed and optimized using this method. The first is a conventional circular patch antenna operating at 5.3 GHz, whereas the second one is a planar loop antenna operating at 3.08 GHz. The third design is a crown-shaped planar antenna (CPA) with a 3 × 3 artificial magnetic conductor (AMC) plane integrated underneath to reduce potential coupling effects from the body. All three antennas are made fully using textiles with the same thicknesses: felt fabric as its substrate and ShieldIt Super as its conductive textile. For all designs, the use of the proposed method, which is validated using the method of moments, has predicted the maximum direction of radiation and its respective gain at the desired frequencies with good accuracy. Besides that, the design of the AMC plane for the CPA is also optimized using CMA prior to the integration with the antenna and a leather wrist strap. Measurements of the final crown-shaped antenna design indicated a good agreement with simulations, with an operating bandwidth of more than 240 MHz, FBR of 15.73 dB and a directional radiation pattern outward from the body.

Creation of a system for designing textile patterns using an iterative function system

“…The creative system is oriented towards the textile field and provides network-based vector textile pattern creative design functions for enterprises in this field [8]. The system also provides information management for textile goods data and user authority management.…”

A monopole antenna with cotton fabric material for wearable applications

“…This challenging role is reflected in the considerations that take when designing such types of antennas. One of these considerations is the influence on the antenna resonance behavior due to the loading effect of the high permittivity body tissue 7 , 8 . On the other hand, in antenna design choosing flexible materials have to be considered to be utilized close to the rounded parts of the human body.…”

A Flexible Multiband Dendritic Structure Fractal Antenna for 4G/5G/WLAN/Bluetooth Applications

“…However, due to the limitations of paper itself, including its fragile nature and the instability of its dielectric constant after being exposed to moisture, paper was not a good dielectric material, but this attempt was still a successful attempt. In literature [15], the authors used leather as the dielectric material for related attempts, and felt was used as the dielectric material in [16], both of which have relatively good performance. In the continuous exploration of antenna technology, people try to apply fractal and bionic theory to antenna design [17].…”