This letter presents a compact reconfigurable multiband microstrip antenna. The multiplicity of bands is achieved by the use of concentric external metallic semirings around a central internal semicircular microstrip patch. These are all shorted to the ground plane via a vertical metallic wall through the common diametric plane, thereby adopting the concept of the planar inverted-F antenna (PIFA) for size reduction and thus compactness. The operation frequencies are tuned by varactor diodes placed between the inner semicircular patch and the outer half-rings. In addition to tunability, the overall bandwidth may also be widened by combining the tunable range. Theoretical simulations and measurements of manufactured prototypes agree well with each other.

https://ir.nctu.edu.tw:443/bitstream/11536/25979/1/000291043800003.pdf

Reconfigurable Loaded Planar Inverted-F Antenna Using Varactor Diodes

A sufficient and simple method to minimize the mutual coupling between closely-spaced microstrip antennas in a H-plane array format, operating at the same frequency is presented. More isolation can be provided through multiple rectangular defected ground structures (DGSs) between the antennas. Interelement mutual coupling before and after using the proposed DGSs is investigated. The length, width and number of the rectangular DGSs have been optimized for more mitigating the mutual coupling (S 12 ). Position of the DGSs is also the other important factor to have a best performance. By using this technique, more than 31 dB isolation between two patch antennas with a side by side distance of only 1/4 free-space wavelength at resonance frequency of 9.2 GHz can be obtained.

A rectangular defected ground structure (DGS) for reduction of mutual coupling between closely-spaced microstrip antennas

This paper proposes and presents a class of substrate integrated waveguide (SIW) power dividers/combiners based on a modified Wilkinson architecture. The proposed design consists of a ring-type circuit of 1.5 λ
 g
 length with three waveguide ports. Impedance variation without affecting cutoff frequency and integration of isolation resistance are the two major limitations in connection with the design of SIW Wilkinson structures. Central ring part with different thickness ensures different impedance in the first proposed scheme while the half-mode SIW in the second option. As for the second limitation, the optimal configuration of integrating the isolation resistance is studied. A version without resistance is also examined using a broad-wall series slot. To validate the proposed concept, a bilayered circuit with standard Printed circuit board prototype was fabricated and measured. A table summarizing performances of all the proposed circuits shows a bandwidth of around 25% at the 10 dB reference. A negligible additional insertion loss is observed. The proposed design techniques are found useful at millimeter-wave frequencies where reduced physical dimensions make a circuit configuration suitable for low-cost implementation. This concept is also valid for rectangular waveguide counterparts.

Ring-Shaped Substrate Integrated Waveguide Wilkinson Power Dividers/Combiners

A study of an innovative antenna based on split ring resonators (SSRs) is presented. SSRs have been exhaustively used in the literature as the unit cell of periodic structures for obtaining left-handed media, whose interesting characteristics can be applied to waveguides or antennas. In this work, the authors propose the use of only one unit cell of a double SRR as a radiator. The double SRR is printed on a grounded dielectric slab, acting as the radiating element of a microstrip patch antenna, and grounded pins are used to short-circuit the structure for size reduction. A compact dual band antenna is obtained in this way. For example, a particular design making use of PP (er = 2.2) as substrate allows a size of 0.05 λ0 x 0.05 λ0 for the lower frequency of operation with an acceptable radiation efficiency. Simulated and measured results of return losses, gain and radiation efficiency of this new type of patch antenna are provided.

https://ir.nctu.edu.tw:443/bitstream/11536/20582/1/000293748500001.pdf

Dual-Band Patch Antennas Based on Short-Circuited Split Ring Resonators

A new multifrequency microstrip patch antenna is presented. The antenna can be considered a PIFA since it has a metallic wall on one of its sides. The different bands of operation are independent of each other, and different radiation patterns for each band can be achieved if desired. In addition, a circuital model is introduced to explain the operation of the antenna. This model presents some similarities with composite right left handed models presented in the literature. Some prototypes have been manufactured and measurements of return losses, efficiencies and radiation patterns, have been performed for a thorough characterization of the antenna as well as to validate the simulation results.

https://publications.lib.chalmers.se/records/fulltext/local_117322.pdf

Compact Loaded PIFA for Multifrequency Applications

Reviews the development work carried out on the antenna for a microstrip patch array operating at 5300 MHz for an active SAR antenna. The work, carried out by Matra Marconi Space, covers the initial design leading up to the present working array. Details of the array and measured results are also presented. >

Microstrip patch array for an active SAR demonstrator

Astrium?s experience with Inmarsat has shown that a satellite designed for mobile telecommunications applications may consist of a large aperture parabolic reflector fed by an array at its principle focus. Both L and S-band are the frequencies of interest. Each radiator element on the array has a one to one correspondence with a spot position on the earth, so that radiation patterns are pointed at different locations on the earth by different combinations of the array element excitations. Before the signals arrive at the array with their specified complex weights they must undergo amplification, which is provided by a beam forming network composed of between 10 and 20 Multi-Port Amplifiers, (MPA).

Design of a multiport amplifier beam forming network for a mobile communications antenna

In order to realize their full potential, future spaceborne, Earth-surveillance, synthetic aperture radars (SARs) will require better antennas than their predecessors; while the steering requirements remain sensibly unaltered, greater fractional bandwidth will often be essential and dual-linear polarization will become a highly desirable feature. Antennas that can meet these anticipated future needs are usually planar phased arrays and potential designs have been reported in the open literature. While the technical efficacy of these reported designs is not in question, it is not clear that antennas based on these designs would be inexpensive to manufacture. This paper describes the work that was done to produce an active antenna that meets the technical needs of future SARs but is relatively inexpensive to manufacture. Finally, it describes such an antenna that has been designed, constructed and tested, and is to be incorporated into a SAR airborne demonstrator.

A wideband microstrip patch array for a MicroSAR

The increasing complexity of today's telecommunications satellites, due to the incorporation of more and more components, coupled with the operators' or user community's desire for increased capabilities is driving the RE modelling of such satellite payloads to new horizons. Greater numbers of channels implies increased bandwidth for the system with a corresponding wider bandwidth of operation for the Beam Forming Network (BFN) and especially the element radiator. Moreover, there is a tendency for the element radiator to be a multi-frequency element resulting in yet more complexity. The beam forming requirements, and consequently the array excitations placed upon one of these antennas, is becoming ever more stringent such that RF modelling has become a critical aspect of the design process. (8 pages)

http://ieeexplore.ieee.org/iel5/4446147/4458235/04458693.pdf

P. James

Papers

Microstrip patch array for an active SAR demonstrator

Design of a multiport amplifier beam forming network for a mobile communications antenna

A wideband microstrip patch array for a MicroSAR

Modeling of a complex beam forming network for a phased array antenna