Electro-textile based wearable patch antenna on biodegradable poly lactic acid (PLA) plastic substrate for 2.45 GHz, ISM band applications

Biodegradable polymers and plastics are environment friendly because they decrease environmental pollution, conserve resources and reduce non-recyclable waste. Poly lactic acid (PLA) is a biodegradable plant derived polymer. Their properties are improved by copolymerization, blending, plasticization, polymer alloy technology and by development of composites techniques. These polymers can be used in computers, mobile phones, housing, textiles, optical, packaging films and bags. In this paper the feasibility of 1.7 and 3 mm thicker PLA as a substrate in wearable patch antenna is investigated. For comparison patch antenna on identically thicker (1.7 and 3 mm) FR-4 substrate is also simulated under the same conditions in CST Microwave Studio. The return loss, gain, directivity and efficiency of both antennas were compared on operating frequency of 2.45GHz. The proposed antenna employing PLA substrates give return losses of -21 and -22dB, gain of 6 and 6.14 dBi, directivity of 7.58 and 7.54dBi and efficiency of 59 and 70% on 1.7and 3mm thicker substrates respectively, while reference antenna using FR4 substrates results in return losses of -19 and -19.3dB, gain of 2.7 and 3.45dBi, directivity of 7.02 and 6.92 dBi and efficiency of 35and 43% for 1.7 and 3 mm thicker FR4 substrates.