This allows different resonances to be turned on and off as desired. Each of these resonant frequencies can be tuned independently by routing the tuning switch connection close to the apex of the voltage distribution for that frequency. Placing tuning switches at multiple locations along the length of a single antenna allows a single antenna to support a wide range of frequency bands that correspond to different natural resonances of the antenna. Signals received by the antenna can then be demultiplexed into individual channels and digital data can be extracted in parallel. First, an individual resonance can be tuned capacitively or inductively the aperture switch plus the antenna acts like an equivalent RLC circuit, which modifies the natural frequencies of the antenna. Typical switch connections for impedance tuning and aperture tuning Aperture TuningĪperture tuning allows a system with an antenna to switch between frequencies in two ways. Aperture tuning ICs typically include enough supporting electronics such that external bypassing and filtering is not necessary, while impedance tuning ICs typically require some external passives for bypassing and filtering. Antenna switches are commercially available as surface-mount ICs. Both methods require the use of an antenna switch to change the resonance frequencies of an antenna. There are two methods used to tune an antenna during operation: impedance tuning and aperture tuning. Antenna tuning can be used to adjust the resonance frequencies back to the intended frequencies. This causes a redshift in the resonant frequencies, thus the scattering parameters shift to lower frequencies. The number of available bands is much larger than the number antennas in a smartphone or other mobile devices, thus the resonances in an antenna must be actively tuned during operation in order to operate in multiple channels simultaneously.Īntenna tuning is also important for compensating changes in the resonance frequency when a mobile device is held in the user’s hand or brought up to the head. In 5G wireless systems, carrier aggregation delivers higher data rates with increased bandwidth by combining at least two carriers with mmWave frequencies, typically in different frequency bands. Antenna tuning techniques allow antenna resonant frequencies to match particular 5G bands simultaneously in order to maximize antenna efficiencies/minimize return loss in the required bands. Note that this does not account for other capabilities like NFC. 5G also mandates four independent downlink channels for most bands, meaning new mobile devices require four antennas for cellular communication. This technique is required in 5G systems that operate beyond WiFi frequencies in order to keep power consumption low, provide the bandwidth required for carrier aggregation.Ĭarrier aggregation and multiple input multiple output (MIMO) require multiple antennas that operate simultaneously. To continue the recent series of articles on PCB design for 5G systems, one other aspect of designing RF design for 5G-capable wireless systems involves a technique called antenna tuning. Whether swinging a whammy bar on stage or just ensuring each string hits the right note, this tuning changes that the resonant frequencies of each to the tone desired by the musician. Guitar players know all about tuning their instruments. 5G antenna tuning is like tuning a guitar as you play
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