Research On Low-Profile Fixed-Frequency Beam-Scanning Antenna

The beam scanning antenna can be divided into a frequency scanning antenna and a fixed frequency scanning antenna.The frequency scanning antenna refers to an antenna whose main beam angle of the pattern changes with the change of frequency.The fixed-frequency scanning antenna refers to an antenna that changes the angle of the main beam of the pattern by changing other parameters when the frequency is fixed.Commonly used in frequency scanning antennas is a leaky wave structure,which has the advantages of simple structure and low profile,and the research theory is mature.However,with the development of wireless communication,many communication devices and mobile terminals work in a specific frequency band,so Frequency-scanning antennas relying on changing the frequency to achieve beam-scanning characteristics are not suitable for most communication systems.Phased array antennas can meet these requirements of modern communication systems,but the system is complex,high-profile and expensive.To this end,this paper proposes a fixed-frequency beam-scanning antenna design,which has the advantages of low profile and easy integration,and has high application value for communication systems with limited space.The main contents and innovations of this paper are as follows:1.A low-profile fixed-frequency beam scanning antenna based on 2-bit unit is proposed.The 2-bit unit has four freely switchable radiated field phases.By changing the phase state of the radiated field of each unit,the main beam angle of the antenna array can be continuously changed from-39°to 38°at 6.2 GHz.With a scan range of 77°;a gain of 13.6 dBi to 16.2 dBi;a radiation efficiency of around 80%and a profile height of 1.611 mm.2.A phase weighted coding method is proposed.For 1-bit array coding,when the phase difference between the inter-cell radiation fields is 180°,the unit radiation fields cancel each other out,which is exactly the opposite of our expectation.In order to reduce this error,a phase weighted coding method is proposed,which introduces a weighting factor of φ.By adjusting the state of the PIN diode,the operating frequency band of the unit with an error greater than ±φ is adjusted outside the working frequency band of the antenna,so that inter-cell radiation can be performed.Field phase difference is reduced to less than 2(p,.3.A fixed-band beam scanning antenna based on 1-bit wide-band unit is proposed,which has the advantages of wide-band and low profile.The frequency band is 25 GHz to 33 GHz;the relative bandwidth is 28.57%;the main beam pointing angle of the antenna pattern can be continuously changed from-60° to 40°,with a scanning range of 100°;the gain is 10 dBi-15 dBi;the height of the profile is 1.14 mm.