A generalized solution to the adaptive nulling problem in the presence of coherent jammers

El-Ayadi, M.H.; Al-Hussaini, Emad K.; El-Hakeim, Eid A.

doi:10.1109/8.204749

Cited by 9 publications

(1 citation statement)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In modern electronic counter measure (ECM) environments, if a scattering object is undetectable for the receiving antenna, it would need to suppress its reflected signal at the specular direction because that by the Snell's law of reflection, most of incident electromagnetic energy will reflect at the angle of reflection that is equal to the incident angle. Although some adaptive nulling algorithms have this performance to make the null of re-transmitted radiation pattern at the angle of reflection [2,3], they may require complicated digital signal processing techniques, giving restrictions on high-frequency and high-speed applications. In this study, a novel approach is developed for a retro-and reflecto-nulling antenna array that this array has two nulls occurring at the incident and specular reflection directions.…”

Section: Introductionmentioning

confidence: 99%

A linear retro- and reflecto-nulling antenna array

Hsieh

Chu

2008

2008 Asia-Pacific Microwave Conference

View full text Add to dashboard Cite

IntroductionBistatic radar systems have been studied and drawn increasing interests in military applications [1]. The system has the advantage of counter-stealth capability and the receiving antenna system is passive, and hence undetectable. In modern electronic counter measure (ECM) environments, if a scattering object is undetectable for the receiving antenna, it would need to suppress its reflected signal at the specular direction because that by the Snell's law of reflection, most of incident electromagnetic energy will reflect at the angle of reflection that is equal to the incident angle. Although some adaptive nulling algorithms have this performance to make the null of re-transmitted radiation pattern at the angle of reflection [2, 3], they may require complicated digital signal processing techniques, giving restrictions on high-frequency and high-speed applications. In this study, a novel approach is developed for a retro-and reflecto-nulling antenna array that this array has two nulls occurring at the incident and specular reflection directions. This approach is implemented by a passive circuit with the use of 90 o hybrids and 90 o phase shifters which are properly connected to transmitting and receiving antennas. Measurement results of a four-element retro-and reflecto-nulling antenna array are presented. DesignConsidering an N-element antenna array, if a uniform plane wave illuminates this array at an incident angle ș i measured from the array broadside, the received signal at the m-th antenna can be given as ( ) ( ) 1 sin 1 , i i j m kd j m m a Ae Ae q f ----= = (1) where m = 1, 2, …, N. k is the wave number of the incident wave and d is the antenna element spacing. If the antenna array retransmits signals with an output signal b m at the m-th antenna, its array factor is given as ( ) ( ) ( ) 1 sin 1 1 1 . o o N N j m kd j m o m m m m F be be q f q ----= = = = å åFor designing a retro-and reflecto-nulling antenna array, one has to arrange two nulls at ș o = ±ș i . The method to arrange two zeros in the array factor is given below. An N-element antenna array which N is a multiple of 4 can be considered as two sub-arrays with spacing of Nd/2. The array factor shown in (2) can then be written as ( ) ( ) ( ) ( ) ( ) 2 2 1 2 1 2 1 1

show abstract

Section: Introductionmentioning

confidence: 99%