Abstract
Reconfigurable antennas play an important role in wireless communication systems as the physical and electrical properties of their structures can be modified, allowing them to be used in different applications. In this paper two reconfigurable filtennas are presented to integrate mobile devices that communicate (uplink and downlink) with satellites in low-orbit constellations. A microstrip patch antenna in uplink mode (29 GHz), is surrounded by copper structure that, once connected via a PIN diode, takes the antenna to resonate in a lower frequency band (20 GHz). To deal with both bands, two filters were integrated into the radiating structure: edge-coupled and hairpin filters. The antennas were characterized and compared through simulation and measurements, in terms of impedance adaptation, radiation pattern and isolation between operating bands, validating their operability. Their small size and low cost allow these antennas to be integrated into mobile terminals that communicate with satellites or 5G systems.
Highlights
The PIN diode was forward biased, connecting the external metal structure to the patch antenna, changing its operation to the lower frequency band, 20 GHz, and the RF signal flows through port 1
In this paper two reconfigurable filtennas for LEO satellite terminals and Internet of Things (IoT) sensors were designed, with the ability of operating at two different frequency bands (20 GHz and 29 GHz), that corresponds to the satellite downlink and uplink frequencies
Two types of filters were used in each structure to achieve better results
Summary
This concept is essential in the wireless communications world because with a single element it is possible to meet different requirements, for different applications, as would be achieved using multiple antennas This reconfiguration is possible using various techniques, including the use of PIN diodes, RF-MEMS (MicroElectro-Mechanical Systems) and varactors, which can act as ON/OFF switches, modifying the physical structure, allowing the change of their properties. Through the connection of two PIN diodes, four patches integrated above the substrate can be connected, changing the antenna’s polarization and allowing slight deviations in the resonant frequency, reaching a bandwidth of 5.07 GHz to 5.95 GHz. A square microstrip antenna with spiral shape is shown in [6], where RF-MEMS are used as ON/OFF switches.
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