Design Of UHF Band Antenna For RFID Reader Applications

Microstrip antennas widely using in different areas of radiofrequency transmitting.It is cheap and easy manufacturing.But it has a number of disadvantages,among which are narrow band,low gain.In this master thesis universal patch antenna is represented.1)Proposed construction consists patch antenna and metal disk array mounting on its.Without disk directors antenna provides omnidirectional properties,with average gain about 2.5 d B.In case of adding metal disks,antenna becomes directivity with average gain coefficient 7.5 d B.Thus,antenna can be using depend on situation like omnidirectional with not high gain,or with high gain and radiation directivity.2)Antenna bandwidth is adapted to UFH range,which is equal to 11%(860 to 960 MHz with central on 910 MHz).But achieved bandwidth value is 24% for omnidirectional antenna and 19% for directional one(result in chapter 4).Antenna has perfect matching with load impedance 50 Ohm,that means antenna can easy use with standard coaxial cable.Average impedance of antenna equals to 49,9 Ohm for omnidirectional and 47.8 Ohm for directional one.Achieved return loss and VSWR coefficients are less than-14 d B and 1.4respectively(less than-20 d B and 1.25 in omnidirectional case).These characteristics are detailed describe in last chapter of this work.3)Calculated total cost of such antenna does not exceed 20 yuan per unit.Thus,antenna is easy for manufacturing and has cheap price,that is mean antenna can be made without special equipment.4)Antenna with guide elements has directivity with opening angle equal 60o degrees()in front direction.Common patch antennas have directivity with opening angle equal 120o.Reducing angle of reading antenna,we also reduce level parasitic reading of tags,which placed close to each other.Thus,proposed antenna can be useful in RFID area applications.Due to not big sizes antenna may be used in mobile RFID reader,with help of omnidirectional properties it can read tags in all directions.It is conveniently in case if tags placed on big boxes,which is difficult to move.Main result of this work is designing of reconfigurable antenna,which provide wide number of characteristics with reducing final cost of its manufacturing.