A CPW‐fed wide‐slot antenna with reconfigurable notch bands for UWB and multi‐band communication applications

Abstract

handling is enough for some applications with a following power amplifier used to amplify the RF pulses.The switching time of the RF-pulse former was measured based on the RF pulse's envelope observed on the digital oscilloscope HP 54124T. The 35-GHz CW signal is gated by the control impulses generated from the impulse generator at the pulse repetition frequency of 100 KHz. The inverters integrated in the RF-pulse former sharpen the rising and falling edges of control impulses, hence eliminating external effects, such as measurement cables and bonding wires, to the switching speed of the RF-pulse former which is mainly determined by the small gate resistor and gate-source capacitor of the MOSFET transistors. The envelope of the 35-GHz RF pulses at the output of the RF-pulse former can be clearly seen on the digital oscilloscope triggered by the trigger signal produced from the impulse generator. Figure 6 shows the measured 0.8-ns RF pulse and its spectrum. There is no RF leakage seen from the measured spectrums; the leakage, if any, is smaller than the magnitude of the actual RF pulse, which demonstrates the ultra-high isolation of the RF-pulse former. From Figure 6(a), the 10-90% rising time and 90-10% falling time of the RF-pulse former are determined to be 136 and 70 ps, respectively. The total measured switching time of 206 ps is 26 ps larger than the simulated result due to the delay in the inverters. The small switching time of 206 ps allows the RF-pulse former to produce very narrow RF pulses for high resolution radar and high-data-rate communication systems. Figure 7 shows the measured 200-ps RF pulse, demonstrating the possibility of generating very narrow pulses.ABSTRACT: In this article, we present a compact wide-slot antenna with reconfigurable notch bands, for ultra-wideband (UWB) and multiband communication applications. The dual band-notch characteristics are realized by using three open-ended stubs inserted into the fork-like radiating element, and the reconfigurable characteristics are achieved by integrating ideal switches in the stubs. By controlling the ON/OFF states of the ideal switches, the proposed antenna can function either as a UWB antenna with two notch-bands, or a single notch-band UWB antenna, or even a multiband antenna. The simulation and measurement results show that the proposed antenna is suitable for UWB as well as multiband communication systems.

Reconfigurable Antennas for UWB Cognitive Radio Communication Applications

“…To provide a good service for CR-UWB communication system, a CR-UWB antenna is required to transmit and receive the desired signals [25][26][27][28][29][30][31][32]. The UWB communication system overlaps with the existing narrowband communication systems, such as WLAN, WiMAX, C-band, radio frequency identification (RFID), and X-band [16][17][18][19].…”

“…Recently, the reconfigurable UWB antennas have been developed for cognitive radio (CR) communications [25][26][27][28][29][30][31][32]. In the CR communication systems, unlicensed users (secondary users) can access spectrum bands licensed to primary users at a spectrum underlay mode or spectrum overlay mode, which is illustrated in Figure 1 [28].…”

“…In other words, the transmission spectrum of UWB radios can be sculpted in accordance with the presence of the primary users in the respective frequency bands [25][26][27][28][29][30][31][32]. Therefore, in CR-UWB systems, a CR antenna should cover the entire UWB band from 3.1to 10.6GHz with no notch bands for underlay applications and for detecting the licensed primary users and providing immunity to these users using band-notched technologies [25][26][27][28][29][30][31][32].…”

A novel CPW‐fed antenna with dual band‐notched charectrestics for UWB applications

“…The antenna is printed on the FR4 substrate with the thickness 1.6 mm and with the relative dielectric constant ε = 4.4. The 50‐Ω CPW feed structure consist of a CPW‐fed transmission line with width of 3 mm and a gap between the transmission line and the CPW ground plane with width g = 0.5 mm . For the impedance matching, the distance between the patch and ground plane is indicated with a gap, which provides proper control between the lower edge patch and the ground plane.…”

Design of printed monopole antenna with band notch characteristics for ultra‐wideband applications

“…The different types of techniques have been introduced by Li. Y et al, [24][25][26][27][28][29] to achieve band notch characteristics such as reconfigurable notch antenna with switching techniques [25][26][27]29 contour fractal techniques, 24 and radial stub loaded technique. 28 Sarkar M. et al 30 explained the compact UWB antenna with dual band notched characteristics at WLAN and Wi-MAX frequency bands.…”