Concept and Design of a Multi-Polarization Reconfigurable Microstrip Antenna with Symmetrical Biasing Control.

Wireless communication systems have grown rapidly, moving towards being highly compact, intelligent, and flexible to adapt to changing operating requirements. Multifunctional and highly versatile antennas are key in this development to ensure system quality. Reconfigurable antennas, particularly regarding polarization, allow frequency reuse and enable the mitigation of fading effects. This work presents a square microstrip patch antenna operating in the ISM 5.8 GHz band with reconfigurable polarization by controlling its feeding. This antenna has four different states through the application of a symmetrical DC voltage that controls an RF circuit with PIN diodes. As a result, the microstrip patch can operate with three different polarizations: linear polarization and both circular polarizations (right-handed and left-handed). The antenna was fabricated to validate the proposed concept. The good agreement between the measurement and the simulation results was possible to observe regarding its polarization behaviour, impedance adaptation and radiation pattern.

Influence of Sex and a High-Fiber Diet on the Gut Microbiome of Alentejano Pigs Raised to Heavy Weights.

This study investigates the influence of sex and a dietary transition on the gut microbiota of a local Portuguese pig breed. Three groups of male Alentejano pigs (n = 10 each) were raised between ~40 and 160 kg LW. Group C included pigs that were surgically castrated, while the I group included intact ones; both were fed with commercial diets. The third group, IExp, included intact pigs that were fed commercial diets until ~130 kg, then replaced by an experimental diet based on legumes and agro-industrial by-products between ~130 and 160 kg. Fecal samples were collected two weeks before slaughter. The total DNA was extracted and used for 16S metabarcoding on a MiSeq® System. The dietary transition from a commercial diet to the experimental diet substantially increased and shifted the diversity observed. Complex carbohydrate fermenting bacteria, such as Ruminococcus spp. and Sphaerochaeta spp., were significantly more abundant in IExp (q < 0.05). On the other hand, castrated pigs presented a significantly lower abundance of the potential probiotic, Roseburia spp. and Lachnospiraceae NK4A136 group (q < 0.01), bacteria commonly associated with better gut health and lower body fat composition. Understanding the role of gut microbiota is paramount to ensure a low skatole deposition and consumers' acceptance of pork products from non-castrated male pigs.

Influence of Sex on Meat and Fat Quality from Heavy Alentejano Pigs Finished Outdoors on Commercial and High Fiber Diets.

This work aimed to examine the effects of sex on meat and fat quality traits from thirty Portuguese Alentejano (AL) pigs reared in outdoor conditions. These pigs were divided into three groups and fed ad libitum. From ~40 to 130 kg LW, castrated (C group) and intact animals (I and IExp) consumed commercial diets. Until slaughter (~160 kg), C and I pigs remained on commercial diets, and IExp changed to a more sustainable experimental diet with locally produced pulses and byproducts. Samples were collected from the Longissimus lumborum (LL), Psoas major (PM), and dorsal subcutaneous fat (DSF). At ~160 kg, the PM muscle of intact pigs presented lower intramuscular fat content than that of C pigs, while total collagen was higher. Additionally, PM myoglobin was lower and lightness (L*) was higher in intact pigs. Regarding DSF, moisture and total protein contents were higher and total lipids were lower in intact than in castrated pigs, while color parameters were not significantly different. Finally, antioxidant capacity measured in the LL muscle showed an overall lower value in intact pigs. However, lipid oxidation values were not significantly different between the experimental groups and only increased with storage time. Outdoor-reared intact AL pigs produced leaner and less saturated pork and fat compared to castrated ones. Despite the lower antioxidant activity observed in the LL muscles of intact pigs, the lipid oxidative stability of cooked meat was not different among the experimental groups.

Transcriptomic Profiling of Subcutaneous Backfat in Castrated and Intact Alentejano Pigs Finished Outdoors with Commercial and Fiber-Rich Diets.

In this work, we studied the backfat transcriptome of surgically castrated (C), intact (I) and intact fed an experimental diet (IE) outdoor-reared male Alentejano (AL) pigs. The experimental diet was a high-fiber diet with locally produced legumes and by-products associated with a boar taint reduction effect. At slaughter (~160 kg), backfat samples were collected for total RNA sequencing. Intact pigs presented leaner carcasses, more total collagen, and more unsaturated intramuscular fat content than C animals. A total of 2726 differentially expressed genes (DEGs, |log2 FC|> 0.58, q < 0.05) were identified between C and I with overexpressed genes related to muscular activity (MYH1, ACTA1) or collagen metabolism (COL1A1, COL1A2) in I pigs. Between C and IE, 1639 DEGs of genes involved in lipidic metabolism (LEP, ME1, FABP4, ELOVL6) were overexpressed in C. Finally, only 28 DEGs were determined between I and IE. Clustering results indicated a drastic influence of the testis in the transcriptome of subcutaneous fat of AL pigs, while the diet had a marginal effect. Diet can reduce stress by increasing satiety in animals, and could have induced an increase of skatole degradation due to the higher expression of the CYP2A19 gene in the IE group.

Outdoor Finishing of Intact Male Portuguese Alentejano Pigs on a Sustainable High-Fiber Diet: Impacts on Blood, Growth, Carcass, Meat Quality and Boar Taint Compounds.

This trial evaluated the effect of sex on the blood, growth, carcass, meat quality, and boar taint compounds in male Alentejano (AL) pigs (n = 30). From ~40 to 130 kg LW, castrated (C) and intact pigs (I and IExp groups) were fed commercial diets ad libitum. Between ~130 and 160 kg (slaughter), C and I pigs continued on commercial diets, while IExp were fed an experimental diet containing locally produced pulses and by-products aimed at reducing boar taint. At ~160 kg, blood urea levels were higher in IExp than C pigs, triacylglycerols were lower in both intact groups, and cortisol was lower in IExp. IExp pigs exhibited faster growth, improved feed conversion ratio, carcass higher commercial yield and leaner meat than C pigs. The loin intramuscular fat in intact pigs was lower, less saturated and more polyunsaturated, while total collagen was higher. Fat androstenone content was higher in intact pigs and skatole content was similar across treatments, although they were below threshold values for consumer detection. Finally, although boar taint compounds were low in intact AL pigs raised outdoors, adding pulses and by-products to the experimental diet did not result in a reduction in fat skatole content compared to pigs fed the commercial diet.

The Use of 3D Printing Technology for Manufacturing Metal Antennas in the 5G/IoT Context.

With the rise of 5G, Internet of Things (IoT), and networks operating in the mmWave frequencies, a huge growth of connected sensors will be a reality, and high gain antennas will be desired to compensate for the propagation issues, and with low cost, characteristics inherent to metallic radiating structures. 3D printing technology is a possible solution in this way, as it can print an object with high precision at a reduced cost. This paper presents different methods to fabricate typical metal antennas using 3D printing technology. These techniques were applied as an example to pyramidal horn antennas designed for a central frequency of 28 GHz. Two techniques were used to metallize a structure that was printed with polylactic acid (PLA), one with copper tape and other with a conductive spray-paint. A third method consists of printing an antenna completely using a conductive filament. All prototypes combine good results with low production cost. The antenna printed with the conductive filament achieved a better gain than the other structures and showed a larger bandwidth. The analysis recognizes the vast potential of these 3D-printed structures for IoT applications, as an alternative to producing conventional commercial antennas.

Compact N-Band Tree-Shaped Multiplexer-Based Antenna Structures for 5G/IoT Mobile Devices.

This paper presents a simple, compact and low-cost design method that allows one to obtain low-profile multi-band antennas for the overcrowded future generation networks, which are widely versatile and very heterogeneous in the K/Ka bands. The proposed antennas comprise n radiating monopoles, one for each of the desired operating frequencies, along with a frequency selective feeding network fed at a single point. This concept enables a single antenna to be shared with different radio-frequency (RF) frontends, potentially saving space. Typically, with n-band structures the biggest challenge is to make them highly efficient and here this is assured by multiplexing the frequency, and thus isolating each of the monopoles, allowing the design of scalable structures which fit the 5G applications. Based on the vision proposed here, a dual-band and a tri-band structures were built and characterized by their main parameters. Both prototypes achieved peak efficiencies around 80%, with adequate bandwidths and gains, as well as great compactness.

Compact Multilayer Yagi-Uda Based Antenna for IoT/5G Sensors.

To increase the capacity and performance of communication systems, the new generation of mobile communications (5G) will use frequency bands in the mmWave region, where new challenges arise. These challenges can be partially overcome by using higher gain antennas, Multiple-Input Multiple-Output (MIMO), or beamforming techniques. Yagi-Uda antennas combine high gain with low cost and reduced size, and might result in compact and efficient antennas to be used in Internet of Thins (IoT) sensors. The design of a compact multilayer Yagi for IoT sensors is presented, operating at 24 GHz, and a comparative analysis with a planar printed version is shown. The stacked prototype reveals an improvement of the antenna's main properties, achieving 10.9 dBi, 2 dBi more than the planar structure. In addition, the multilayer antenna shows larger bandwidth than the planar; 6.9 GHz compared with 4.42 GHz. The analysis conducted acknowledges the huge potential of these stacked structures for IoT applications, as an alternative to planar implementations.