Cannabinoids have been known for their analgesic, anxiolytic, antiemetic and antispastic properties for many centuries. Previous reports from our lab showed that intravesical administration of liposomal protect against acetic acid induced bladder hyperactivity. In the present study, we determined the effect of Ajulemic acid (AJA) on baseline and chemically evoked release of the sensory neuropeptide, calcitonin gene-related peptide in an isolated bladder preparation.

An element-by-element approach to the modelling of arrays of finite size enables the elements to be located on arbitrary lattices, including those curved in more than one plane. An analysis for dual-polarised ring-patch elements is given. Planar and parabolic surfaces are used as examples, with the rings on circular and triangular lattices. They are illuminated by plane waves. The currents induced across the arrays are very dependent on element location as well as on frequency. The transmission performance of these curved frequency-selective surfaces is also discussed, including the effect on the current induced in an element located inside a paraboloidal dichroic enclosure.

This paper presents results from a project studying horn antennas in which a change in beamwidth is produced by a corresponding change in an electronically variable input parameter. The beamwidth of a horn can be altered by changing either the effective transmitting aperture, and/or by modifying the amplitude/phase distribution over it. Initial experimental prototypes successfully demonstrated the feasibility of achieving as much as a 1:3 change in beamwidth with H-plane sectoral horns. The technique has now been successfully extended to pyramidal horns to produce variable patterns in both principal planes.

The purpose of this paper is to present some results from an on-going study of curved frequency selective surfaces (FSS). Here we consider an FSS consisting of an array of ring slots in a conducting sheet, centrally embedded in a dielectric

Frequency selective surfaces are usually formed from arrays of elements printed on dielectric substrates or sandwiched between dielectric layers. They can be modelled using Floquet modal techniques when they are periodic and plane and infinite or curved into a complete cylinder. Arbitrarily curved finite surfaces present greater problems because it becomes necessary to perform the computations for groups of elements or for individual elements in the array. One approach is to use a ray tracing method. Instead, this paper studies curved arrays formed from a finite number of dipoles or rings that are free standing, and illuminated by an incident plane wave or line source. The analysis is similar to the Pocklington equation method applied previously by Allam and Parker (1987) to finite planar dipole arrays. Examples of singly and doubly curved arrays are shown

In order to study the effects of a dielectric embedded FSS on an enclosed antenna pattern, the authors adopt the ray tracing technique to compute the near field pattern of the antenna-FSS configuration exterior to the structure, from which the transmission coefficient and the far field patterns can be calculated. They use parabolic and paraboloidal shapes formed from a dielectric slab with an embedded slot ring FSS which, when it is planar, provides a flat passband transmission window. Rings have been chosen with a view to minimise polarization dependence of the element although the method is applicable to arbitrary FSS arrays and surfaces of arbitrary shape. The approach adopted is based on tracing multiple ray paths through the curved dielectric slab with the FSS treated as an infinitesimally thin interface with known reflection and transmission coefficients. In this manner, a structure composed of an FSS embedded in a dielectric can be treated as a series of interfaces where the incident ray is partially specularly reflected and partially transmitted according to the reflection and transmission dyadics at the point of incidence, until it emerges on the other side of the radome or decays to a level below a prescribed threshold. With a sufficiently dense bundle of input rays from the source, the radiation pattern transmitted through the radome can be computed using two dimensional interpolation on the transmitted rays

An experimental H-plane sectoral horn with interior active FSS wall in the E-plane is described. The FSS is switchable between transmitting and reflecting states, which enables the horn beamwidth to be varied.<>

Finite frequency selective surfaces (FSS) embedded in a curved dielectric are analysed using the ray-tracing technique. The FSS is treated as an infinitesimally thin interface with known complex reflection and transmission coefficients subjected to multiple interactions with rays internally reflected within the dielectric; Results for flat surfaces agree well with those computed using a full modal analysis. The transmission properties of such arrays are studied as the curvature is steadily increased for the case of paraboloids illuminated by plane waves, and also when enclosing a finite aperture-type antenna. The results obtained are validated by measurement.

An H-plane sectoral horn contains ferrite powder dispersed in a solid low-loss dielectric medium. The permeability of the medium is varied by an externally applied magnetic field to alter the phase distribution across the horn aperture to produce a variable beamwidth horn.<>

Interaction between an antenna and an enclosing FSS is investigated using the Pocklington equation approach from an earlier study of arbitrarily curved free-standing arrays of dipoles. Part of such a collection of elements can be regarded as a receiving antenna, and the rest can be distributed around it to form a dichroic enclosure, It is then possible to analyse this structure with and without mutual coupling between the two sets of dipoles, to give an indication of antenna-radome coupling in a simple case.

Profiled dielectric loaded horns are investigated with the aim of obtaining low peak crosspolar level and high aperture efficiency. A number of nonlinear profiles are considered. The paper also looks into the influence of profiling on the bandwidth of the horn and the effect of nonuniformities in the dielectric material on horn performance.

Finite curved dipole frequency-selective arrays are analyzed using an integral equation to solve for the current distribution in the array elements. This article studies the effect of finiteness and curvature on the current distribution in the dipoles and on the transmission performance of the array. Results obtained are compared with measured values. (C) 1994 John Wiley & Sons, Inc.

A dielectric lens is integrated into a dielectric loaded horn antenna to produce a high efficiency feed for reflectors. The lens is designed using simple ray theory and analysed using modal matching techniques. Aperture efficiencies of up to 78% are achieved while retaining good crosspolar performance.

We have successfully grown ferromagnetic MnGa ultrathin films on GaAs substrates by molecular beam epitaxy. Reflection high energy electron diffraction and cross-sectional transmission electron microscopy show that monocrystalline MnGa films are grown with the c axis of the tetragonal unit cell normal to the (001) GaAs substrates. Both magnetization measurements by vibrating sample magnetometer and extraordinary Hall effect (EHE) measurements indicate perpendicular magnetization, with the remnant magnetization of 225 emu/cm3 and EHE resistivity in the range of 0.5–4 μΩ cm at room temperature. The material possesses properties ideal for certain nonvolatile magnetic memory coupled with underlying III-V circuitry.

We have created a new class of epitaxial magnetic multilayers consisting of ultrathin monocrystalline layers of two different metallic compounds, MnGa and NiGa, on GaAs substrates. In-situ RHEED and ex-situ TEM characterizations show that the MnGa/NiGa multilayers are formed with the desired epitaxial orientations. Magnetization and magnetotransport measurements indicate perpendicular magnetization at room temperature, thus making this material a promising candidate for nonvolatile magnetic memory coupled with underlying III–V circuitry.

The dielectric cone loaded horn consists of a central cone of solid or foam dielectric supported by a second dielectric with a metallised outer layer. The horn has low cross-polarisation over a wide bandwidth and the absence of flanges means better utilisation of the aperture area. The dielectric gives an additional method of controlling the fields in the horn. The authors investigates dielectric loaded horns with a shaped profile. They show that the profiled dielectric horn gives useful control over the performance of the horn. It can be designed in two distinct ways. Either the length of the horn can be kept the same as a linear tapered horn which will give improved electrical performance, or the length (and weight) of the horn can be reduced by comparison with the linear horn, whilst maintaining similar low levels of cross-polarisation

Curved arrays of a finite number of dipoles are analysed using the vector potential equation to compute the current distribution in each dipole in the array, taking into account mutual coupling among the elements. The frequency selective characteristics of such curved arrays are compared with finite and infinite planar arrays. The effect of mutual coupling on the transmission characteristics of the arrays is also discussed.

The dielectric cone loaded horns have good potential to be used as high performance feed horns, but they need some means of accurately supporting the dielectric cone in the smooth wall metal horn. The paper reports a new version of the horn which has two novel innovations. Firstly the central foam dielectric cone is surrounded by a second foam dielectric with a lower permittivity. This ensures that the dielectric cone is accurately positioned. Secondly the metal walls are produced by depositing a thin copper layer directly onto the dielectric. This provides the conducting wall for the horn and also reduces the weight of the horn by a significant amount. The result is a horn which is lightweight and compact. The paper describes the theoretical technique used to design the horn and reports a parametric study of the relevant parameters for the dielectric cone loaded horn. The design and manufacture of the new horn is then described together with the measured performance and possible future developments