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A frequency reconfigurable patch antenna is dynamically tuned to transmit frequency-shift keying (FSK) signals over a range of frequencies much broader than the static impedance bandwidth of the antenna. Experiments are conducted for two binary FSK schemes having different carrier spacing. In both cases, dynamic tuning of the antenna is shown to increase the amplitude of the radiated signal by providing a better match than the static antenna. However, the average energy of the radiated bit at each carrier frequency decreases as the symbol rate increases beyond the 3 dB bandwidth of the antenna. Therefore, the bandwidth of the antenna is found to be a limiting factor for the maximum achievable data rate in this scheme. As an alternative to shorter bit durations, the authors show that a higher level FSK scheme using dynamic tuning is able to increase throughput beyond what is possible with a static antenna.

A dynamically switched matching network for transmitting a wideband frequency shift keyed (FSK) signal from an electrically small monopole antenna is studied. The effects of switch synchronization, frequency deviation, the antenna's impedance, and Q-factor at the two carrier frequencies are studied. It is found that the average energy per bit of the transmitted FSK waveform is maximum when the loss of reactive energy between states transition is minimised by switching it at the instant of peak voltage across the antenna's terminals. However, a switching network topology that stores more energy is shown to be less sensitive to the synchronization condition. In addition, we show that this dynamically switched system transmits more bit energy when the carriers are closely spaced due to a smaller change in stored energy levels between states. Results are presented using a detailed analytical study and full wave simulation. Near field measurements from a monopole antenna circuit model show that under proper conditions, an FSK signal can be transmitted at a rate 7 times greater than the bandwidth of the transmit antenna with minimal signal quality degradation.

A wideband patch loaded dielectric resonator antenna (DRA) is discussed here. The rectangular ring shaped slot coupling is used to excite the proposed antenna. In this paper, rectangular ring shaped slot coupled DRA and patch loaded DRA is studied and compared. The combined effect of patch radiator with rectangular ring shaped slot coupled DRA, on the return loss is observed. Simulation is done using Ansoft HFSS which is based on finite element method. Simple DRA resonates at two frequencies centered at 2.25 GHz having return loss of -14.41 db and 4.61GHz with a return loss of -19.29db; The patch loaded DRA shows resonance at frequencies centered around 2.19GHz having return loss of -32.3db and 4.4GHz with a return loss of -29.18db.The patch loaded DRA is based on the multi resonance technique that combines the resonance of slot coupled dielectric resonator and micro strip patch antenna. The bandwidth achieved for simple DRA is 26.8 % while patch loaded DRA offers 44.1 %.As the patch loaded DRA has larger bandwidth, may be used for wideband WLAN applications like WiFi, Bluetooth, Wimax etc. General TermsBroadband, WLAN,antenna

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