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A switched‐line substrate integrated waveguide 1‐bit phase shifter is designed and measured at 28 GHz. Reconfigurability is achieved through a set of floating metallized vias whose connection to the waveguide top and bottom layers can be controlled using PIN diodes. The reconfigurable vias are used to dynamically create alternative paths having different phase delays. A three‐metal layer printed circuit board stack‐up is employed to fully integrate the diode biasing network and to ease the routing of the bias signal. The high integration of the proposed configuration makes it well suited for the implementation of reconfigurable Butler matrices. The phase shift offset between the two states of this digital 1‐bit phase shifter equals 262° at 28 GHz, leading to a measured figure of merit of 161°/dB, and input 1‐dB compression point over 20 dBm. The total area is 13.72 × 10.9 mm without feeding lines and bias.

This study presents the first monolithically integrated full-duplex front-end for K/Ka satellite communication phased arrays. A 0.25 μm SiGe:C BiCMOS process was used to develop the integrated circuit. The receive and transmit channels are united into a common port through a novel duplexer. For each RF channel, the bias currents, the active channels and the power amplifier operation mode can be controlled through a serial bus. Amplitude and phase control are provided with fine granularity (65,536 states). In transmit mode, each channel provides 37.3 dB of gain with 12.9 dBm output power at 1-dB compression. In receive mode, 33.7 dB gain is measured with a noise figure of 3.2 dB. The amplitude/phase root-mean-square errors within the transmit (29.5–30.8 GHz) and receive (19.7–21 GHz) bands are below 0.7 dB/ 6.4 ° and 0.26 dB/ 1.1 ° , respectively. The chip occupies 1.64 × 3.5 m m 2 and it consumes 81 and 15.5 mW per transmit and receive channels, respectively. The use of a Doherty power amplifier with a novel dynamic adaptive bias circuit led to a 31% reduction of the total dc array power consumption.

This study demonstrates a hybrid technology for the implementation of efficient feeding networks in K-band arrays. In the proposed hybrid structure, the main part of the distribution network consists of dielectric-loaded E-plane metallic waveguides, whereas stripline circuits that depart from the waveguides are used to feed the radiators. The efficiency of the hybrid feeding network is verified on a 4×4 dual-polarised array of circular waveguides operating in the K band. Details on the characteristics of the loaded waveguide and the array elements, and on the construction of the overall structure are given. Measured results are presented and discussed in order to demonstrate that the hybrid waveguide×stripline structures are a promising technology for the creation of efficient feeding networks at higher frequencies.

Even with the advances in signal processing, multipath error remains the major error source of high-precision global positioning system (GPS) applications. One of the most valid means to improve the accuracy of these systems is an appropriate design of the receiving antenna. Unfortunately, in many cases, the low-multipath-radiation requirements are very difficult to satisfy especially when physical constraints have also to be considered. As a possible solution, a study on the multipath rejection performances of shorted annular patch (SAP) antennas is presented here. In the first part, the SAP radiation characteristics will be deeply analysed by designing and testing three different antennas. Then, the results of a comparative test conducted on a GPS facility will be used to assess the on-field performances of the three prototypes. This experimental validation will show that a significant improvement of the SAP performances can be achieved when the reduced surface wave criterion, which has been widely adopted as a design rule in previous works, is relaxed and a trade-off between all the low-multipath-radiation requirements is considered. Moreover, comparison with two commercial GPS antennas will reveal that SAPs can be a very attractive and useful solution in high-precision GPS systems where severe physical constraints are imposed.