Effective wireless low‐power transmission using a phased array antenna

Beam-steering antennas are the ideal solution for a variety of system applications, it is most commonly achieved through using phased arrays, where phase shifters are used to control the relative of the main-beam. In this paper, a low-cost directive beam-steering phased array (DBS-PA) antenna using switched line phase shifters is demonstrated. The proposed DBS-PA antenna has four micro-strip patch antennas, three power dividers and four phase shifters printed on the same Rogers RT-Durroid substrate with a dielectric constant of 2.2 with dimensions of 8 × 3.5 cm. The phased array antenna has a directivity of 15 dBi and the main beam direction can be switched between the angles of ±30 degrees with a 3dB beam-width of 25 degrees. All design and simulations have been carried out using Agilent AdS and Ansoft HFSS software tools. The frequency considered for the operation is 10 GHz.

Abstract. The antenna cross polarization suppression (CPS) is of significant importance for the accurate calculation of polarimetric weather radar moments. State-of-the-art reflector antennas fulfill these requirements, but phased array antennas are changing their CPS during the main beam shift, off-broadside direction. Since the cross polarization (x-pol) of the array pattern is affected by the x-pol element factor, the single antenna element should be designed for maximum CPS, not only at broadside, but also for the complete angular electronic scan (e-scan) range of the phased array antenna main beam positions. Different methods for reducing the x-pol radiation from microstrip patch antenna elements, available from literature sources, are discussed and summarized. The potential x-pol sources from probe fed microstrip patch antennas are investigated. Due to the lack of literature references, circular and square shaped X-Band radiators are compared in their x-pol performance and the microstrip patch antenna size variation was analyzed for improved x-pol pattern. Furthermore, the most promising technique for the reduction of x-pol radiation, namely "differential feeding with two RF signals 180° out of phase", is compared to single fed patch antennas and thoroughly investigated for phased array applications with simulation results from CST MICROWAVE STUDIO (CST MWS). A new explanation for the excellent port isolation of dual linear polarized and differential fed patch antennas is given graphically. The antenna radiation pattern from single fed and differential fed microstrip patch antennas are analyzed and the shapes of the x-pol patterns are discussed with the well-known cavity model. Moreover, two new visual based electromagnetic approaches for the explanation of the x-pol generation will be given: the field line approach and the surface current distribution approach provide new insight in understanding the generation of x-pol component in microstrip patch antenna radiation patterns.

An artificial transmission line based on Barium-Strontium-Titanate (BST) thick-film is used as a phase shifter in this work. The benefits of artificial transmission lines are exploited to realize a very compact phase shifter with a length of 3mm for 342° differential phase shift. The prototyped phase shifter exhibits a figure of merit (FoM) of 52°/dB in the frequency range 8–10 GHz. The proposed circuit is fabricated in only one photolithography process cycle on a low cost screen printed thick-film ceramic.

The design details of K band 6 bit digital phase shifter circuit in 65nm CMOS technology (MMIC) for phased array antennae in general and active phased array antennae in particular, are presented in this paper. The circuit is composed of Si CMOS switches and filter based phase shifting network. The 6 bits are designed individually using the lumped equivalents and then connected together. The switches form an integral part of the design. The parasitic impedances associated with the switches are compensated in the design. With 6 bits, a total of 64 states are derived with different switching combination, and coverage of 360 is achieved. The insertion loss is observed to be <tex>$-13\pm 6.5$</tex> dB and the input and output matching was greater than 5 dB over the band of 19&#x2013;20 GHz. The RMS phase error achieved is 3&#x00B0; at the centre frequency of 20 GHz. The area of the design is <tex>$1.255\ \text{mm}\times 0.424\ \text{mm}$</tex>, the circuit operates at 1.2V and the power consumed is almost low.

Phased array antenna capable of providing wider scanning range of beam radiation. The conventional phased array antenna mostly covered a single polarization of beam radiation. Therefore, by improving the phased array antenna design by implementing dual polarization will enhance the capacity of beam radiation to radiate at wide angular angle. A dual linearly polarized phased array antenna slanted at ±45° has been designed to operate at frequency of 28 GHz by using CST tool. Based on the simulation performance, the reflection coefficient (S11) and radiation pattern of both single and array antenna shows a good performance. The S11 value for both single and array antenna are -11.36 dB, and -20.17 dB, respectively. The gain of single slanted -45°, single slanted +45°, and 1x2 ±45° array patch antenna are 7.48 dB, 7.47 dB, and 7.08 dB.

Phased array antenna is widely used in military field, so the fault diagnosis of phased array antenna is an important research topic. Conventional near-field and far-field pattern testing methods consider all the radiating elements as a whole. These methods focus on how to measure the antenna pattern, and can hardly locate the antenna fault to single radiating element. To repair the phased array antenna, the fault radiating element must be located. Usually, fault locating needs to test all the radiating elements one by one. In this paper, we propose a new method to test many elements at one time. This method is based on subarray testing and cosine similarity. We divide the phased array antenna into many small subarrays, and using several test antennas in the middle-field of the antenna under test to get a set of data. These data contain the amplitudes and phases of the antenna's main lobe and side lobe. Then, using cosine similarity to compare those test data with fault data in expert database, the fault radiating elements can be located. Simulation and field test show that this method can distinguish different faults in the phased array antenna caused by different radiating elements.

A space-fed X-band phased array antenna (PAA) is presented. The space-fed PAA uses physically autonomous individually addressable unit cells as the building blocks of an arbitrarily large array antenna. The X-band PAA unit cell consists of both a feed facing printed antenna element and a target facing printed antenna element. These elements are related by an RF phase shifter placed in the RF signal path between them which introduces relative phase delay and enables analog beam forming. Unit cell autonomy is realized by wirelessly transferring power and command signals required to operate a microcontroller (MCU) and the RF phase shifter at each unit cell. Each unit cell includes RF to DC conversion circuitry as well as an MCU designed to interpret a common control signal and command unit cell phase delay. The wireless phased array unit cell can be replicated in configurations of size and shape that are independent of RF, power, and array module control distribution networks. To demonstrate feasibility a four-element wireless PAA is constructed and antenna patterns for various control states are shown.

Phased Array Antennas (PAAs), using patch -radiating elements, are projected to transmit data at rates several orders of magnitu de higher than currently offered with reflector -based systems. However, there are a number of potential sources of degradation in the Bit Error Rate (BER) performance of the communications link that are unique to PAA -based links. Short spacing of radiatin g elements can induce mutual coupling between radiating elements, long spacing can induce grating lobes, modulo 2� phase errors can add to Inter - Symbol Interference (ISI), and phase shifters and power divider network introduce losses into the system. This paper describes efforts underway to test and evaluate the effects of the performance degrading features of phased - array antennas when used in a high data rate modulation link. The system effects created by small increments in the scan angle, as would be experienced during a LEO system passing over a fixed point on the ground, have been simulated in the far field environment and analyzed. Computer simulation of the system under test has also been conducted by creating models using Matlab/Simulink. Variations of the test configuration, including a lower carrier frequency to data rate ratio and various modulation schemes, have been analyzed with these models. The results from the experimentation and simulation will be discussed and the impact for future implementations will be examined.

This paper presents the design of an electronically scanning phased array antenna which is constituted using 130 RF MEMS capacitive switches conflated with a series of linearly placed micro strip rectangular inset feed patch antennas and a corporate feed network. The design and analysis is performed in Ansoft HFSS (version 13.0). As the urge of obtaining high radiation pattern, light weight, low cost and better performance over wide range of frequencies, the micro strip antennas is still in demand. A phased array antenna using high-Q metal-insulator-metal capacitors which are intended as loading elements in the phase shifter have been designed in this context. The simulated result sights the designed 4-bit DMTL phase shifter which provides nearly 22.5°/45°/90°/180° phase shifts for different combination of MEMS switches. The design is optimized for Ku band at 15 GHz and the return loss for the phased array antenna is annexed to be -27.41dB. A highly integrated structure has been designed on silicon substrate having an area of 3.1×1.9cm2 only.

A 94-GHz phased array antenna using a log-periodic antenna has been developed on a GaAs substrate. The developed phased array antenna comprises four log-periodic antennas, a phase shifter, and a Wilkinson power divider. This antenna was fabricated using the standard microwave monolithic integrated circuit (MMIC) process including an air bridge for unipolar circuit implementations on the same GaAs substrate. The total chip size of the fabricated phased array antenna is 4.8 mm × 4.5 mm. Measurement results showed that the fabricated phased array antenna had a very wide band performance from 80 GHz to 110 GHz with return loss characteristics better than -10 dB. In the center frequency of 94 GHz, the fabricated phased array antenna showed a return loss of -16 dB and a gain of 4.43 dBi. The developed antenna is expected to be widely applied in many applications at W-band frequency.

Microstrip antennas or patch antennas are popular for their attractive features such as low profile, low weight, low cost, ease of fabrication and integration with RF devices. Micro strip antennas have been found favorable because they are inexpensive to manufacture and compatible with monolithic microwave integrated circuit designs (MMIC). They are usually employed at UHF and higher frequencies because the size of the antenna is directly tied to the wavelength at the resonance frequency. A Microstrip or patch antenna is a narrowband, wide-beam antenna fabricated by etching the antenna element pattern in metal trace bonded to an insulating dielectric substrate with a continuous metal layer bonded to the opposite side of the substrate which forms a ground plane. The most commonly employed microstrip antenna is a rectangular patch. The major disadvantages of Microstrip antennas are lower gain and very narrow bandwidth. Microstrip patch antennas have some drawbacks of low efficiency, narrow bandwidth (3-6%) of the central frequency. Millimeter wave technology being an emerging area is still much undeveloped. As micro strip antennas have found wide variety of application areas, a number of techniques are evolved to improve its limited bandwidth. A good approach to improve the bandwidth is increasing the thickness of substrate supporting the micro strip patch. However problems exist on the ability to effectively feed the patch on a thick substrate and the radiation efficiency can degrade with increasing substrate thickness. A substantial research needs to be done in this area as its applications are numerous. The radiation patterns and S11 performance are used for the analysis of the different configurations. In the present endeavor a rectangular patch antenna is designed on thick substrate and simulated using MATLAB software and configuration on different dielectric susbstrates was used .

This paper presents a unique design concept for a dual-frequency,electronically steerable, MM-wave phased array antenna using Monolithic Microwave Integrated Circuit (MMIC) technology. Such an antenna design will be found most attractive for satellite communication and missile seeker applications, where size, weight and power consumption are the most stringent requirements. The block diagram of a dual-frequency (20 GHz/30 GHz), electronically steerable, phased array antenna using MMIC technology is shown in Figure 1. Specific details on the critical RF components are also shown in Figure 1. Because of the location of the radiating elements on the hemispherical surface, the antenna is inherently capable of providing electronic scanning over 360 deg. in AZ-plane and over plus/minus 60 deg. in EL-plane. This electronically steerable phased array antenna will generate multiple beams in the AZ-plane with consistent bandwidth and pattern symmetry. This design exploits true integration of printed circuit antenna technology, GaAs active device technology, MM-wave microstrip technology and printed circuit time delay phase shifting element technology. This design employs microstrip periodic structure transmission line sections as time delay phasing elements, which requires no input power. The printed circuit microstrip line sections will be used as feed networks. Two distinct dual- frequency, antenna element fabrication techniques, namely, stacked-patch element (Figure 2a) and collocated, interleaved-patch element (Figure 2b), were investigated in terms of cost, size, performance and complexity. Tradeoff studies performed seem to indicate that stacked-patch element approach will offer minimum size and weight. The physical dimensions shown in Figure 1 and 2 are computed for 20 GHz and 30 GHz operations. All the electronics, control circuits and RF MMIC circuits can be located within the hemispherical structure. The input power, overall system size and weight will depend on the antenna gain requirement, inter-element spacing, number of elements and phase shifter types. It is important to mention that delay line phasing networks using printed circuit periodic structures will provide optimum flexibility in phasing of the antenna elements with minimum loss. The proposed antenna architecture for a dual-frequency operation using a common aperture and MMIC technology seems to offer an antenna system with minimum cost, size, weight and power consumption.

Microwave phased array antennas (PAAs) are very attractive to defense applications and high-speed wireless communications for their abilities of fast beam scanning and complex beam pattern control. However, traditional PAAs based on phase shifters suffer from the beam-squint problem and have limited bandwidths. True-time-delay (TTD) beamforming based on low-loss photonic delay lines can solve this problem. But it is still quite challenging to build large-scale photonic TTD beamformers due to their high hardware complexity. In this paper, we demonstrate a photonic TTD beamforming network based on a miniature microresonator frequency comb (microcomb) source and dispersive time delay. A method incorporating optical phase modulation and programmable spectral shaping is proposed for positive and negative apodization weighting to achieve arbitrary microwave beam pattern control. The experimentally demonstrated TTD beamforming network can support a PAA with 21 elements. The microwave frequency range is $\mathbf{8\sim20\ {GHz}}$, and the beam scanning range is $\mathbf{\pm 60.2^\circ}$. Detailed measurements of the microwave amplitudes and phases are performed. The beamforming performances of Gaussian, rectangular beams and beam notch steering are evaluated through simulations by assuming a uniform radiating antenna array. The scheme can potentially support larger PAAs with hundreds of elements by increasing the number of comb lines with broadband microcomb generation.

Conventional method of beam scanning such as phased array antenna is costly by using multiple antenna elements and phase shifters. In this communication, a different method is investigated to achieve beam scanning. A multimode concentric circular microstrip patch antenna on a single substrate layer backed by a finite ground plane is presented where radiation patterns are reconfigurable. Pattern reconfiguration is achieved by exciting higher order TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n1</sub> modes in addition to the dominant TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode. Next, limited beam scan performance for linear polarization by employing mode combination and control of the amplitude and phase values is demonstrated. A prototype multimode patch antenna was fabricated and experimentally verified for the individual modes impedance matching and radiation patterns which showed acceptable agreement. The beam scan performance for a selected combination of modes of the patch was also measured.

Phased array antennas are becoming more and more ubiquitous largely in part because of the provision within the 5G protocol for millimeter-wave beamforming. As silicon phased array beamforming core chips become widely available, this opens cost effective solutions for highly agile line of sight (LOS) communications links which utilize classical phased array antennas. This paper describes the development and demonstration of a 0.4 km RF link which operates in the Ku-Band (13.8 GHz), which supports up to 30 Mbps data rates. The developed system is demonstrated utilizing laboratory instruments as well as with a small form factor radio. The developed phased array antenna is able to maintain link at 0.4 km at scan angles up to ±60°, utilizing a digitally modulated signal (32-QAM) at a symbol rate of 5 Msym/s while maintaining an RMS EVM of less than 6%.