A deterministic procedure to design a nonperiodic
planar array radiating a rotationally symmetric pencil beam pattern
with an adjustable sidelobe level is proposed. The elements
positions are derived by modifying the peculiar locations of the
sunflower seeds in such a way that the corresponding spatial
density fits a Taylor amplitude tapering law which guarantees
the pattern requirements in terms of beamwidth and sidelobe
level. Different configurations, based on a Voronoi cell spatial
tessellation of the radiative aperture, are presented, having as
a benchmark the requirements for a typical multibeam satellite
antenna.

Maria Carolina Vigan&#243;

Giovanni Toso

Gerard Caille

Cyril Mangenot

Ioan E. Lager

Sunflower Array Antenna with Adjustable Density Taper

An overview about some of the recent Spanish developments on active reflectors is presented. In the first part, a novel beamsteering active reflectarray is deeply studied. It is based on implementing in each elementary radiator an IQ modulator structure, in which amplitude and phase control of the scattered field is achieved. Finally, a special effort is made in offering solutions to overcome the active antenna integration problems. In the second part, the active concept is firstly extended to Fresnel reflectors. Thanks to the development of a proper simulator, this special structure can be easily analysed. This simulator allows the study of performance of this kind of reflectors and, applying evolutionary algorithms, to find optimal configurations of reflector in accordance with the given specifications for the conformal radiation pattern.

Lorena Cabria

Jos&#233; &#193;ngel Garc&#237;a

Julio Guti&#233;rrez-R&#237;os

Antonio Taz&#243;n

Juan Vassal&#39;lo

Active Reflectors: Possible Solutions Based on Reflectarrays and Fresnel Reflectors

The design, manufacturing, and measurements of a switchable-beam antenna at 3.5&#x2009;GHz for WLL or Wimax base station antennas in planar technology are presented. This antenna performs a discrete beam scan of a <svg     style="vertical-align:-0.1638pt;width:21.475px;" id="M1" height="13.1375" version="1.1" viewBox="0 0 21.475 13.1375" width="21.475"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
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			<g transform="matrix(.012,-0,0,-.012,16.375,4.712)"><path id="x2218" d="M326 255q0 -56 -41 -96t-99 -40t-99 40t-41 96t41 96t99 40t99 -40t41 -96zM274 255q0 38 -25.5 65t-62.5 27t-62.5 -27t-25.5 -65t25.5 -65t62.5 -27t62.5 27t25.5 65z" /></g>

		
	
</svg> sector in azimuth and can be easily upgraded to 5 or more steps. The switching capabilities have been implemented by the inclusion of phase shifters based on PIN diodes in the feed network following a strategy that allows the reduction of the number of switches compared to a classic design. The measurements show that the design objectives have been achieved and encourage the application of the acquired experience in antennas for space applications, such as X-band SAR and Ku-band DBS.

Mariano Barba

Juan E. Page

Jose A. Encinar

Planar C-Band Antenna with Electronically Controllable Switched Beams

Novel approaches of tunable devices for millimeter wave applications based on liquid crystal (LC) are presented. In the first part of the paper, a novel concept of a tunable LC phase shifter realized in Low Temperature Cofired Ceramics technology is shown while the second part of the paper deals with a tunable high-gain antenna based on an LC tunable reflectarray. The reflectarray features continuously beam scanning in between <svg     style="vertical-align:-0.3003pt;width:31.4625px;" id="M1" height="13.3125" version="1.1" viewBox="0 0 31.4625 13.3125" width="31.4625"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,12.875)"><path id="xB1" d="M535 290h-212v-206h-58v206h-213v50h213v193h58v-193h212v-50zM535 -22h-483v50h483v-50z" /></g><g transform="matrix(.017,-0,0,-.017,10.041,12.875)"><path id="x32" d="M412 140l28 -9q0 -2 -35 -131h-373v23q112 112 161 170q59 70 92 127t33 115q0 63 -31 98t-86 35q-75 0 -137 -93l-22 20l57 81q55 59 135 59q69 0 118.5 -46.5t49.5 -122.5q0 -62 -29.5 -114t-102.5 -130l-141 -149h186q42 0 58.5 10.5t38.5 56.5z" /></g><g transform="matrix(.017,-0,0,-.017,18.2,12.875)"><path id="x35" d="M153 550l-26 -186q79 31 111 31q90 0 141.5 -51t51.5 -119q0 -93 -89 -166q-85 -69 -173 -71q-32 0 -61.5 11.5t-41.5 23.5q-18 17 -17 34q2 16 22 33q14 9 26 -1q61 -50 124 -50q60 0 93 43.5t33 104.5q0 69 -41.5 110t-121.5 41q-53 0 -102 -20l38 305h286l6 -8&#xA;l-26 -65h-233z" /></g>

			<g transform="matrix(.012,-0,0,-.012,26.363,4.712)"><path id="x2218" d="M326 255q0 -56 -41 -96t-99 -40t-99 40t-41 96t41 96t99 40t99 -40t41 -96zM274 255q0 38 -25.5 65t-62.5 27t-62.5 -27t-25.5 -65t25.5 -65t62.5 -27t62.5 27t25.5 65z" /></g>

		
	
</svg>. Also first investigations on radiation hardness of LCs are carried out, indicating that LCs might be suitable for space applications.

A. Gaebler

A. Moessinger

F. Goelden

A. Manabe

M. Goebel

R. Follmann

D. Koether

C. Modes

A. Kipka

M. Deckelmann

T. Rabe

B. Schulz

P. Kuchenbecker

A. Lapanik

S. Mueller

W. Haase

R. Jakoby

Liquid Crystal-Reconfigurable Antenna Concepts for Space Applications at Microwave and Millimeter Waves

This paper presents new results showing the application of polyomino-based subarrays to limited field of view and wideband, wide-angle scanning. This technology can reduce the number of phase controls in arrays used for limited sector coverage or the number of time delay devices for wideband radar or communications, and so can reduce the cost of space-based active arrays. We concentrate on the wideband application. Results are presented by comparing the gain and peak sidelobe results of irregular polyomino subarray-based arrays with those of rectangular subarrays. It is shown that using irregular polyomino subarrays can result in a major decrease in sidelobes while presenting, in most cases, only a few tenths of a dB gain reduction compared to rectangular subarrays.

R. J. Mailloux

S. G. Santarelli

T. M. Roberts

D. Luu

Irregular Polyomino-Shaped Subarrays for Space-Based Active Arrays

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<p><em>International Journal of Antennas and Propagation </em>publishes research on the design, analysis, and applications of antennas, along with studies related to the propagation of electromagnetic waves through space, air, and other media.</p>


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International Journal of Antennas and Propagation publishes research on the design, analysis, and applications of antennas, along with studies related to the propagation of electromagnetic waves through space, air, and other media.

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