Near-Field Direct Antenna Modulation (NFDAM) transmitter at 2.4GHz
ABSTRACT A near-field direct antenna modulation (NFDAM) transmitter at 2.4GHz is demonstrated on a microstrip setting. The transmitter is capable of transmitting information in a direction-dependent fashion by sending the correct signal constellation only in the desired direction while leaving the signal constellation points scrambled in undesired directions. This direction-dependent constellation scrambling nature of the NFDAM systems prevents undesired receivers to correctly demodulate the signal transmitted to a desired receiver at a specific direction.
Full-textDOI: · Available from: Aydin Babakhani, Jul 22, 2014
- SourceAvailable from: Yuan Ding
[Show abstract] [Hide abstract]
- "DM physical realization has been the subject of various studies. In    a DM architecture, which relies on the near-field coupling effects, was proposed. However, the deployment of a large number of parasitic array elements, as well as the unavailability of effective synthesis methods, may hinder its further development. "
ABSTRACT: A 10 GHz Fourier Rotman lens enabled dynamic directional modulation (DM) transmitter is experimentally evaluated. Bit error rate (BER) performance is obtained via real-time data transmission. It is shown that Fourier Rotman DM functionality enhances system security performance in terms of narrower decodable low BER region and higher BER values associated with BER sidelobes especially under high signal to noise ratio (SNR) scenarios. This enhancement is achieved by controlled corruption of constellation diagrams in IQ space by orthogonal injection of interference. Furthermore, the paper gives the first report of a functional dual-beam DM transmitter, which has the capability of simultaneously projecting two independent data streams into two different spatial directions while simultaneously scrambling the information signals along all other directions.International Journal of Antennas and Propagation 03/2015; 2015. DOI:10.1155/2015/285986 · 0.83 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: A direction dependent antenna modulation system based on a simple two element phased array is presented. By applying discrete phase shifts to the elements of the array, data modulation can be imparted on to the transmitted signal. The form of the modulation then becomes dependent on the transmission angle. It is shown that such a system provides a degree of transmission security and this is demonstrated by calculating the error rate of the system as a function of observation angle. I. INTRODUCTION Direction dependent antenna modulation has recently been proposed as a technique that can be used to enhance the security of a wireless communication link (1), (2). The concept is probably easiest to describe by considering a line of sight communication system. In a conventional system data modulation is introduced at baseband frequencies before being up-converted to RF and radiated by an antenna. To provide some degree of transmission security a directional transmit antenna may be used in order to reduce the level of the transmitted signal in unwanted directions. However, although the magnitude of the signal is reduced, the time-dependent form of the modulated signal remains constant with direction. Hence, an eavesdropper monitoring a sidelobe radiated signal with a sensitive receiver could easily intercept the transmission. Consider now an alternative system in which data modulation is applied by directly modifying the radiation characteristics of the transmit antenna. Such a system can be configured to exhibit signal modulation characteristics which are a function of the angular direction of radiation and this introduces an additional degree of complexity which makes signal demodulation by an eavesdropper a much more difficult task.
- [Show abstract] [Hide abstract]
ABSTRACT: A direction dependent communication system based on a simple two element array is described. The system is similar to a conventional phased array but the phase shifters have only 2-bit control. The basic concept of directional antenna modulation is presented and illustrative examples are given. Some of the system characteristics of direction dependent modulation are examined and compared to conventional modulation systems. A simple two element array system configured for direction dependent modulation is introduced and numerical examples are given to illustrate how transmission error rates depend on various system parameters.