# Broadband Microstrip Antenna for 5G Wireless Systems Operating at 28 GHz
## 3 Frequency Range for Local Multipoint Distribution Service  
The technological solutions used in the 5G system eliminate the disadvantages of LTE. These solutions make use of very high frequencies (in a 28 GHz millimeter band) and beamforming techniques. In that, several clients within the range of the same base station can use a 1 Gbps internet connection.  
The usefulness of the 28 GHz band is limited, in particular, because of requirements applying to transmission between the user and the base station (the \"upstream\" link). The 28 GHz frequency band has been made available by the Federal Communications Commission (FCC) by reallocating the local multipoint block distribution service (LMDS) A1, which is 850 MHz wide and lies between 27.50 and 28.35 GHz bands [8; 9; 10].  
In response to the growing demand for an additional frequency spectrum, mostly for fixed/mobile 5G applications that require significant bandwidth to support higher speeds >1.0 Gbps at a lower latency, the Federal Communications Commission (FCC) has ordered the A1 channel and reallocated it as part of the new Upper Microwave Flexible Use License (UMFUS). The ordered part of the frequency spectrum has been transformed into a new licensing system based on two 425 MHz wide blocks (blocks L1 and L2) [11; 10; 12; 13]. The division of the LMDS spectrum in the 28 GHz frequency band is presented in Figure 1.  
The 28 GHz band and other millimeter frequency bands (mmWave), such as 24 GHz and 37/39 GHz bands, will play a key role in 5G implementations under the new Upper Microwave Flexible Use License (UMFUS). The UMFUS bands are standardized for 3 GPP in accordance with 5G New Radio (NR) guidelines, in particular within Frequency Band 2 (FR2), which includes millimeter frequencies.  
The UMFUS bands are currently maintained and used by national mobile phone operators, innovative mobile phone companies, regional phone operators, and other organizations wishing to implement mobile networks or provide fixed wireless access (FWA) services [8; 9; 10].  
The UMFUS bands are subject to rules and regulations, which impose power limits at fixed and base stations operating in conjunction with mobile systems (EIRP density  
Figure 1: The 28 GHz (27.50–28.35 GHz) local multipoint distribution service (LMDS) spectrum.  
limit + 75 dBm/100 MHz). The average power of the sum of all antenna components in a mobile base station must not exceed a maximum EIRP value of +43 dBm. Network deployments may use any desired duplex scheme, provided that other technical or operational requirements are met [13].  
The 28 GHz band is ideal for a wide range of applications making use of speeds >1 Gb/s (depending on channel size), which are achievable using the spectrum designated by UMFUS. High-speed backhaul, \"at home\" 5G/FWA, and other applications make use of the ability to implement fixed PTP (point-to-point) and PTMP (point-to-multi-point) configurations. The 28 GHz band can also be used for mobile applications, which are currently a key pillar of 5G deployment championed by national carriers and other organizations [11; 12; 13].