## 1 Introduction
Massive antenna arrays using up to 128 elements, increasing performance and gain of radar communication systems are presented in [10], taking advantage of digital beamforming based on coded aperture radar (CAR) technique at 77 GHz. In [11, 12, 13], the importance of the beamforming spectral efficiency is demonstrated, with the cancelation of undesired interferences by placing nulls in their directions that can lead to a lower bit error rate (BER). In [14], there is a software-defined phased array radio operating at 28 GHz that uses software to control multiple beam characteristics. However, additional hardware was required, a field programmable gate array (FPGA) board for digital control and an Ettus B200 mini software-defined radio (SDR) for data waveform control. In [15], a highly compact 28 GHz complementary metal-oxide-semiconductor (CMOS) integrated circuit (IC) with multiple input multiple output (MIMO) and beamforming capabilities with a single wire for baseband multiplexing is reported. Figure 1: Modern environment of multicommunication systems. However, it requires heavy digital signal processing (DSP) MIMO operations to retrieve the information. A similar concept was recently shown in [16], proposing a digital array receiver for satellite applications, also integrating DSP algorithms, operating in a single-chip RF system on chip (SoC) solution installed on the Xilinx ZCU1275 prototyping platform; however, operating in a fixed frequency range between 27.5 and 28.35 GHz. A 64-channel massive MIMO transceiver with a fully digital beamforming (DBF) architecture is presented in [17]. The MIMO transceiver operates in time division duplex (TDD) mode, at 28 GHz with a 500 MHz signal bandwidth. A high data rate in the communication was achieved using the beam-tracking technique and two streams of 64-QAM (Quadrature Amplitude Modulation) signals. However, one of the great difficulties of this architecture is the high cost of the hardware structure that supports the 64 channels. Due to the high power consumption of the RF frontends, additional space in the circuit is required for heat dissipation. A Ka band DBF array transmitter using a direct digital synthesizer (DDS) for millimeter-wave applications is proposed in [18], operating at 24 GHz. This system reveals a complex calibration and has fluctuation over different scanning angles that unbalance the gain of different beam peaks in the \(1\times 15\) antenna array. In [19], the implementation of an X band \(4\times 4\) digital phased array module is shown, which includes one custom CMOS RF SoC. This system has high side lobes due to the transmitter (Tx) calibration process that involves random errors both in the phase and magnitude. The concept of beamforming, in the sense of the ability to control the radiation shape of an antenna array, can be performed either digitally, like the examples presented previously [14; 15; 16; 17; 18; 19], analogically (by using the frontend analog phase shifters [20]) or in a hybrid way [21]. A millimeter-wave hybrid beamforming system architecture based on analog phased subarray is reported in [22]. This work uses a 32-element antenna array with a hybrid beamforming transceiver to operate at the 28 GHz band in TDD mode, with 500 MHz bandwidth. An important aspect is the reduction in the number of intermediate frequency (IF) channels compared to [14; 15; 16; 17; 18; 19], reducing the cost comparing to fully digital architectures. However, one issue with this architecture is the analog phase shifting, which is critical to increasing the insertion loss up to 19.5 dB, requiring the use of additional amplifiers to compensate such losses. Additionally, this architecture has a higher complex design of the control signal because of the non-linearity between the control signals (amplitude weighting control) and output phase of this vector-sum phase.