International audienceAdiabatic potential energy, spectroscopic constants, dipole moments, and vibrational levels have been computed for the lowest electronic states of alkali dimers LiX and NaX (X = Rb, Cs). Calculations have been carried with the use of an ab initio approach with core-potential potentials and full-valence configuration. Thus, these systems are treated as two-electron systems. A good agreement is obtained for some lowest states of the molecules studied with available theoretical works. The existence of numerous avoided crossings between electronic states for 1Σ symmetries is related to the charge-transfer process in each molecule between its two ionic systems (Li+X−, Li−X+) and (Na+X−, Na−X+)

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This paper focuses on the 60 GHz band, which is known to be very attractive for enabling next-generation abundant multi-Gbps wireless connectivity in 5G communication. We propose a novel concept of a double-layer antenna, loosely inspired from standard log-periodic schemes but with an aperiodic geometry, reduced size, and a limited number of elements while achieving excellent performance over the entire 60 GHz band. To maximize the antenna's efficiency, we have developed a design that differs from those traditionally used for millimeter-wave communication applications. We aim to simultaneously maximize the gain, efficiency, and bandwidth. The reflection coefficient of the proposed design achieves a bandwidth of 20.66% from 53.9 GHz up to 66.3 GHz, covering the entire frequency band of interest. In addition, this proposed structure achieves a maximum realized gain of 11.8 dBi with an estimated radiation efficiency of 91.2%. The proposed antenna is simulated, fabricated, and tested in an anechoic chamber environment. The measurement data show a reasonable agreement with the simulation results, with respect to the bandwidth, gain, and side-lobe level over the operational spectrum.2 of 12 paradigm, a printed antenna based on microstrip technology is a suitable alternative for satisfying the desired requirements. However, conventionally, microstrip antennas designed at the MMW bands typically exhibit low gain, low efficiency due to substrates' losses, and narrow bandwidth [3]. Typically, for an emblematic wireless application, the desired physical and electrical specifications of the MMW antennas are achieved by carefully selecting an appropriate antenna terminology, with an advanced technology used for prototyping and realization by adopting suitable design approaches with modifications to the conventional antenna types [4]. Antenna arrays are usually used for high-gain frontend MMW wireless terminals [5]. However, such an approach is discouraged due to the considerable power losses and loss of compactness because of the mismatches among various circuit elements and the extended feeding network. In reference [6], an MMW antenna array operating at 60 GHz was designed and tested. The designed array of 16 × 16 elements exhibits a high gain of 30.5 dBi but with a low efficiency of around 40%. An antenna array of 10 elements operating at 60 GHz was presented that exhibits a maximum gain of 13 dBi with an efficiency of 63% [7]. In references [8] and [9], typical arrays of patch antenna elements were chosen to achieve high-gain. The realized gain cannot be higher than 19.6 dBi and 17.5 dBi using the 4 × 4 elements. However, both types of arrays operate over a wide bandwidth, which is around 27.5%. As an alternative, to enhance the bandwidth and the gain of microstrip-based antennas simultaneously, an aperture-coupled feeding approach has been suggested [9][10][11][12]. However, micromachining is required for the development of the multilayer circuits, which increases the complexity, cost, and vulnerability to the fabricatio...

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