Abstract: A communication system includes first and second devices which are matched to each other. At least one of the matched devices includes an input device for capturing content; a memory for storing the content, and a renderer configured to render the content under the control of at least one processor which is configured to affect rendering of the content on the first device and/or the second device in response to at least one trigger. The least one trigger may be generated in response to detection of a user of the first device; passage of time the content has been rendered since a previous trigger; location of the user; behavioral pattern of the user; and/or traffic flow patterns between the first device and the second device.

Abstract: A communication system includes first and second devices which are matched to each other. At least one of the matched devices includes an input device for capturing content; a memory for storing the content, and a renderer configured to render the content under the control of at least one processor which is configured to affect rendering of the content on the first device and/or the second device in response to at least one trigger. The least one trigger may be generated in response to detection of a user of the first device; passage of time the content has been rendered since a previous trigger; location of the user; behavioral pattern of the user; and/or traffic flow patterns between the first device and the second device.

Abstract: An input signal for a travelling wave or distributed amplifier having input and output transmission lines is supplied to one end (1) of the input line and an output signal is derived from one end (4) of the output line. Conventionally, the other end (2, 3) of each line is terminated in a respective matched load, but three ports of the amplifier may be employed. The travelling wave amplifier may be used to replace a circulator (CIRC, FIG. 2) in an FMCW radar having a single transmitting/receiving antenna (ANT) (TWAMP1, FIG. 3), to replace a directional coupler (DC) for supplying a local oscillator signal to a mixer (MXR) (TWAMP2, FIG. 4), and in combination with a mixer diode (D) to form a mixer amplifier (TWAMP3, FIG. 3), giving the possibility of the larger-scale integration of RF circuits.

Abstract: An injection-locked waveguide oscillator comprises a first diode (3) having a free-running fundamental frequency above the local cut-off frequency of the waveguide (1) and a second diode (4) having a fundamental frequency below and a higher harmonic above the local cut-off frequency. The first diode (3) may be an IMPATT diode and the second diode (4) a Gunn diode. The free-running fundamental frequency of the first diode (3) is close to the higher harmonic of the second diode (4) so that the second diode (4) injection-locks the first (3). Locking in the reverse sense is inhibited by the inherent loss in conversion from the higher harmonic to the fundamental in the second diode (4), thus avoiding the need for a circulator or isolator. The two diodes (3, 4) preferably are mounted in a common waveguide (1) for a simple compact structure.

Abstract: A microwave oscillator suitable for millimeter wavelengths comprises a Gunn diode (3) coupled to a waveguide (1) by a resonant-cap structure (5,6). The diode (3) generates microwave energy both at a fundamental frequency f.sub.o which is below the cut-off frequency of the waveguide (1) and at a second harmonic frequency 2f.sub.o above cut-off. To control the generation of microwave energy at 2f.sub.o, energy at f.sub.o is coupled into the waveguide (1) from an adjacent further waveguide (9) above its cut-off, by means of an electric probe (8) extending close to the cap (5). The probe (8) may couple in a locking signal at or close to the free-running value of f.sub.o from another oscillator having better noise performance and electronic tuning, thereby locking 2f.sub.o to twice the frequency of the locking signal, or alternatively may couple to a varactor-tuned cavity resonant at f.sub.o.

Abstract: An R.F. circuit with at least one R.F. transmission line including a strip conductor (15) and a ground plane (13) on an insulating substrate (3) and having two diodes (24, 25) respectively D.C.-connected to two portions (38,39) of the ground plane (13). The two portions are mutually D.C.-isolated by a slot (37) to enable the diodes (24, 25) to be biased. The substrate (3) is mounted in a housing (1, 2) of conductive material, and the two portions (38, 39) of the ground plane (13) are mutually R.F.-coupled via the conductive material. One of the portions (39) is electrically-connected to an adjacent housing member (2) and the other portion (38) is separated therefrom by a thin insulating layer. The slot (37) inhibits coupling of R.F. energy out of the circuit into the slot (37), suitably being very narrow, e.g. 20 .mu.m, so as to form a further transmission line with a very low characteristic impedance and also to have a high attenuation along its length for operation at mm-wavelengths.

Abstract: An R.F. balanced mixer comprises on an insulating substrate (3) with opposed major surfaces a balanced first transmission line having a pair of conductors (18, 19) on a first major surface and an unbalanced second transmission line having a strip conductor (15) on one major surface and a ground conductor (13) on the side of the substrate (3) remote from the strip conductor (15). Two diodes (24, 25) are electrically connected between the pair of conductors (18, 19) of the first line and the strip conductor (15) of the second line to form an arrangement operable as a 180.degree. hybrid junction, the first line coupling an R.F. signal to the diodes (24, 25) and the second line coupling an L.O. signal to and an I.F. signal from the diodes (24, 25). To reduce the impedance of the I.F.