Photoconductive antennas (PCAs) have been extensively utilized for the generation and detection of both pulsed broadband and single frequency continuous wave terahertz (THz) band radiation. These devices form the basis of many THz imaging and spectroscopy systems, which have demonstrated promising applications in various industries and research fields. The development of THz PCA technology through the last 30 years is reviewed. The key modalities of improving device performance are identified, and literature is reviewed to summarize the progress made in these areas. The goal of this review is to provide a collection of all relevant literature to bring researchers up to date on the current state and remaining challenges of THz PCA technology.

https://www.spiedigitallibrary.org/journals/optical-engineering/volume-56/issue-1/010901/Review-of-terahertz-photoconductive-antenna-technology/10.1117/1.OE.56.1.010901.pdf

Review of terahertz photoconductive antenna technology

This letter proposes a novel printed monopole antenna for ultrawideband applications with dual band-notch function. The antenna consists of a square radiating patch with a pair of L-shaped slits, and an E-shaped slot and a ground plane with a V-shaped protruded strip, which provides a wide usable fractional bandwidth of more than 140% (2.89-17.83 GHz). In order to generate single band-notch characteristics, we use two L-shaped slits in the radiating patch. By adding an E-shaped slot in the center of the radiating patch, a dual band-notch function is achieved. Also, by inserting a V-shaped protruded in the ground plane, additional resonances are excited, and hence much wider impedance bandwidth can be produced, especially at the higher band. The measured results reveal that the presented dual band-notch monopole antenna offers a very wide bandwidth with two notched bands, covering all the 5.2/5.8-GHz WLAN, 3.5/5.5-GHz WiMAX and 4-GHz C-bands. The designed antenna has a small size area of 10 × 16 mm2, which has a size reduction of 35% with respect to the previous similar antenna.

Dual Band-Notched Square Monopole Antenna for Ultrawideband Applications

A novel printed monopole antenna with constant gain over a wide bandwidth for ultra wideband applications with desired notch-band characteristic is presented. The proposed antenna consists of a square-ring radiating patch with a pair of T-shaped strips protruded inside the square ring and a coupled T-shaped strip and a ground plane with a protruded strip, which provides a wide us able fractional bandwidth of more than 130% (3.07-14.6 GHz). By using the square-ring radiating patch with a pair of T-shaped strips protruded inside it, the frequency bandstop performance is generated, and we can control its characteristics such as band-notch frequency and its bandwidth by electromagnetically adjusting coupling between a pair of T-shaped strips protruded inside the square ring. The designed antenna has a small size of 12 × 18 mm2, or about 0.15λ × 0.25λ at 4.2 GHz, while showing the band-rejection performance in the frequency band of 5.05-5.95 GHz.

Band-Notched Small Square-Ring Antenna With a Pair of T-Shaped Strips Protruded Inside the Square Ring for UWB Applications

In this letter, a novel printed frequency-reconfigurable microstrip square slot antenna for switchable Bluetooth, WiMAX, and WLAN applications is presented. The proposed antenna has a small size of $20 \times 20~\hbox{mm}^2$ in order to be able to cover lower frequencies; as for Bluetooth applications, miniaturization techniques such as modification of the ground plane and inserting an adjustable backplane cross-shaped sleeve have been employed. Moreover, by implementation of p-i-n diodes within the antenna structure, switchable frequency responses are achieved. The presented antenna has a small size while providing suitable switchable radiations at 2.3–2.51 GHz $({\rm BW} = 8.7\%)$ Bluetooth, 3.35–3.75 GHz $({\rm BW} = 11.2\%)$ WiMAX, and 4.95–5.53 GHz $({\rm BW}=11\%)$ WLAN.

Design of a Reconfigurable Miniaturized Microstrip Antenna for Switchable Multiband Systems

Numerical study of heat transfer and blood flow in two-layered porous liver tissue during microwave ablation process using single and double slot antenna

In this article, a novel square monopole antenna for ultra wideband applications with variable frequency band-notch characteristic is presented. By using T-shaped slots, additional resonances are excited and hence, the fractional bandwidth is increased up to 150%. A modified T-shaped conductor-backed plane is used to generate the frequency band-stop performance. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 2065–2069, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25395

Microstrip-fed small square monopole antenna for UWB application with variable band-notched function

In this paper, a new design of multi-resonance monopole antenna for use in microwave imaging systems is presented. The antenna conflguration consists of an ordinary square radiating patch, a feed-line, and a modifled ground plane with pairs of L-shaped slits and parasitic structures which provides a wide usable fractional bandwidth of more than 130% (2.95{14.27GHz). In the presented design, by cutting a pair of L-shaped slits and also by embedding a pair of inverted L-shaped parasitic structures in the ground plane additional resonances at 9.5GHz and 13.7GHz can be achieved. By using these structures, the usable upper frequency of the antenna is extended from 10.3GHz to 14.27GHz. The proposed antenna has a symmetrical structure with ordinary square radiating patch, therefore displays good omni-directional radiation patterns even at higher frequencies. The antenna has su-cient and acceptable gain level and also its radiation e-ciency is greater than 86% across the entire radiating band. The designed antenna has a small dimension.

/pdf/uwb-omni-directional-microstrip-monopole-antenna-for-31l6ycbp4p.pdf

UWB/Omni-Directional Microstrip Monopole Antenna for Microwave Imaging Applications

In this paper, a novel printed monopole antenna for ultra wideband applications with variable frequency band-notch characteristic is presented. The proposed antenna consists of a stepped square radiating patch with modifled W-shaped slot and a ground plane with rectangular sleeve and pair of L-shaped resonator which provides a wide usable fractional bandwidth of more than 130% (3.05{14.3GHz). By cutting a modifled W-shaped slot with variable dimensions on the radiating patch frequency band-stop performance is generated and we can control its characteristics such as band-notch frequency and its bandwidth. The designed antenna has a small size of 12 £ 18mm 2 while showing the band rejection performance in the frequency band of 5.08 to 5.91GHz.

https://www.jpier.org/pierc/pierc15/11.10061802.pdf

Ultra-Wideband Small Square Monopole Antenna with Variable Frequency Band-Notch Function

A dual band-notched printed ultra-wideband monopole antenna is presented, with a modified radiating patch.To generate single and dual band-notched characteristics, we use two rectangular slots. By properly adjusting the dimensions of these slots two controllable notch resonances are achieved, but also the lower edge frequency of the band is decreased. The measured results show that the proposed dual band-notched monopole antenna offers a wide bandwidth from 2.5 to 11 GHz, with two notched bands, covering all the 5.2/5.8 GHz wireless local area network, 3.5/5.5-GHz WiMAX and 4-GHz C bands. The designed antenna has a small size of 12 × 18 mm2. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:372–374, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26571

Ultra-wideband small square monopole antenna with dual band-notched function

Self-complementary structures are used to design a novel compact band-stop filter for X-band applications. By cutting a rectangular slot with five pairs of L-shaped protruded strips inside the slot on the ground plane and by inserting five pairs of L-shaped stubs in the microstrip transmission line, the self-complementary structure is created, hence a constant and flat impedance bandwidth at the X-band can be produced. The operating frequencies of the filter can be easily controlled by changing the dimensions of the protruded L-shaped strips and stubs, without changing the area taken up by the structure. Experimental results show good agreement with simulation results and demonstrate that excellent stop-band performance could be obtained through the proposed band-stop filter.

M. Ojaroudi

Papers

Microstrip-fed small square monopole antenna for UWB application with variable band-notched function

UWB/Omni-Directional Microstrip Monopole Antenna for Microwave Imaging Applications

Ultra-Wideband Small Square Monopole Antenna with Variable Frequency Band-Notch Function

Ultra-wideband small square monopole antenna with dual band-notched function

Very compact broad band-stop filter using periodic l-shaped stubs based on self-complementary structure for x-band application