Rectangular microstrips with variable air gap and varying aspect ratio: Improved formulations and experiments

Abstract

relative excitation amplitudes of the modes. Three different cases were studied in terms of the relative permittivity r2 of the TM 02 patch, while keeping r1 ϭ 1.15 for the TM 11 mode. It was found that as r2 increased, the phase centre location of the antenna moved further away from its physical centre, over a given angular range of the far field. The largest phase centre displacement of about 0.3 was achieved, for a peak 50°phase variation, in Case III. The concept provides a simple and yet practical method for moving the antenna phase centre, without mechanically moving the antenna itself. This attractive feature can be useful in applications like beam shaping, global positioning systems, virtual arrays, adaptive pattern controls, and reflector antenna applications. ABSTRACT:The resonant modes and characteristics of a rectangular microstrip with a variable air gap are theoretically and experimentally examined. Effect of varying width to length ratio is another important aspect addressed and a computer aided design is presented. Thorough experiments are presented, a few of which are reported for the first time. ABSTRACT:We present a single-pass L-band erbium doped fiber amplifier (EDFA) based on a large mode area (LMA) fiber. A single transverse mode is maintained through restricted mode launch. Pump light near 974 nm is sent into the core and has high spatial overlap with the signal beam, helping to preserve single mode propagation. Up to ϩ27 dB of pump power limited small signal gain (30 W signal input) with a noise figure (NF) near 4.4 is achieved in a relatively short fiber [b].

Rectangular patch on air and air-dielectric composite substrates to achieve improved radiation characteristics

“…The radiation characteristics have been experimentally studied using a set of prototypes and the results are compared with the measurements employing uniform PTFE and air substrates for identical patches. The patch having a commonly used aspect ratio WIL ::::1.5 (L = 12 mm and W =17.73 mm) has been theoretically designed using the recent formulations in [7] to operate around X-band. Taconic 's TLY-3-0620 has been used as the PTFE substrate.…”

Software enabled cognitive radio antenna system

“…When the air gap has a zero height the microstrip antenna behaves as a conventional microstrip antenna [2]. The cavity model of the microstrip antenna tells us that the excitation of the TM mn depends on the location of the feed which in our case, is transmission line fed [2]. The fringing of the electric fields from the edges of the patch is also affected by the variable air gap thickness and it is accounted for in our calculation and analysis.…”

“…Both operations (vertical movement or tilt) introduce an air gap with a variable height, change the substrate's effective dielectric constant and transform the antenna into a suspended microstrip antenna with variable air gap. When the air gap has a zero height the microstrip antenna behaves as a conventional microstrip antenna [2]. The cavity model of the microstrip antenna tells us that the excitation of the TM mn depends on the location of the feed which in our case, is transmission line fed [2].…”

Design and Development of Coax-Fed Electromagnetically Coupled Stacked Rectangular Patch Antenna for Broad Band Application

“…The effective permittivity of this two-layer structure ( Fig. 2) is obtained as [34]: Figure 4. Geometry of upper cavity.…”