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In this paper, a study on the effects of strategically implemented holes in a miniaturized wideband bandpass filter (BPF) utilizing interdigital folded coupled lines is presented. First, the BPF is designed to produce the passband by introducing a fold in the coupled lines. The passband is centered at 9.3 GHz (X‐band), catering to radar applications. Coupled lines connected to a modified U‐shaped transmission line comprise the filter's design configuration. The novelty of the design resides in incorporating drilled holes along the coupled lines, which generate perturbations and resonant effects, resulting in enhanced impedance variations and improved filter performance. With the aid of electromagnetic analysis and simulation software, the coupled lines, U‐shaped transmission lines, and drilled hole diameters are all optimized. Vector Network Analyzer performs all the measurements and draws the comparisons. An increment of 22.58% is seen in return loss as it increases from −24 to −32 dB, and the insertion loss shows an increase of 16.74%. The proposed filter has been subjected to analytical study, simulation, and implementation, which have confirmed its exceptional return loss, favorable insertion loss, and compact dimensions. The research results make a valuable contribution to the development of miniaturized wideband BPFs, specifically focusing on their use in radar systems. In such systems, the ability to accurately and efficiently filter signals is paramount. The design insights and performance improvements presented in this study have significant implications for broader applications in microwave engineering and communication systems. [ABSTRACT FROM AUTHOR]

This study presents a planar dual‐channel bandpass microstrip diplexer based on a novel structure. It has the very compact size of 0.0081 λg2 (95.7 mm2) fabricated on 0.787 mm dielectric substrate height. Due to the use of close microstrip sections, several coupling capacitors are created. These capacitors can increase the degree of freedom for controlling the diplexer performance while it is optimized easily. Accordingly, the designed diplexer has a high performance in terms of wide fractional bandwidths, attenuated harmonics, flat channels, high return losses and low insertion losses. The wide fractional bandwidths (FBWs%) of 34.3% at the first channel and 38.6% at the second channel make the proposed diplexer appropriate for the broadband applications. The resonance frequencies are located at f1 = 1.6 GHz for the L‐band and f2 = 3 GHz for WiMAX applications. The maximum harmonic level is less than −20 dB for the frequencies up to 6.5 GHz (4f1). The maximum group delays are <1.26 ns at the first passband and 0.56 ns at the second passband. The proposed diplexer is fabricated and measured for verification. The comparison shows that both measured and simulated results are in a reasonable agreement. [ABSTRACT FROM AUTHOR]

A compact monopole ultra wide band (UWB) antenna is analyzed and described with defect in ground plane. By introducing four arcs at the edges of square patch is achieved an UWB antenna ranging from 3.1 to 10 GHz. Arranging the antenna elements in close proximity of spatial diversity is introduced without establishing the strong mutual coupling. The measured IBW's (impedance bandwidth's) are 3.0 to 4.0 GHz (1000 MHz), 5.6 to 4.3 GHz (1300 MHz), and 9.5 to 8.4 GHz (1100 MHz) occupied the bandwidth from 2.0 to 10.0 GHz which covers Bluetooth, WLAN, and ultra wideband for VSWR ≤2. The average value of the gain in antenna is 5.04 dBi with a small variation of ±1.20 dBi for the whole entire IBW. This antenna shows better radiation patterns like an omnidirectional with a narrow compact size having an area of 2100 mm2 (60 × 35 mm) and spacing between the two square patches is 0.05 λ0. [ABSTRACT FROM AUTHOR]

Using circular and rectangular resonators, a new design of a compact microstrip lowpass filter (LPF) with negligible losses is proposed and fabricated. The proposed LPF has a 3 dB cut‐off frequency at 1.375 GHz with an adjusting range of 14.5%; moreover, the suggested configuration leads to a competitive roll‐off rate of 189 dB/ GHz and a negligible group delay of 0.47 ns. Attenuator cells have capability to produce numerous transmission zeros (TZs) at high frequencies; consequently, an ultra‐wide stopband (14 fc) with high suppression level (25 dB) is successfully obtained. Furthermore, the LPF has a small size of 0.067λg × 0.134λg (λg is the guided wavelength at 1.375 GHz). The transfer function is also calculated to adjust the location of the main TZs and the cut‐off frequency. Finally, an acceptable similarity between the simulated results and the tested ones verifies the simulation results. [ABSTRACT FROM AUTHOR]

Abstract: A complementary coupled spiral transmission line with center via is proposed to design band pass filter with compact and simple profile, low group delay, and low insertion loss. A compact wideband band pass filter is designed and fabricated for demonstration which has 26% bandwidth, 0.3 dB insertion loss, and compact size as 0.41 × 0.23 λg with very low group delay, 0.28 ns. These good specifications prove the capability of the proposed approach to design of band pass filter compared with the literatures. [ABSTRACT FROM AUTHOR]

A new method for optical fiber group delay measurement is proposed and experimentally demonstrated based on laser beat frequency. When the laser wavelength in the optical fiber resonator changes, the time delay through the optical fiber under test will change accordingly, leading to a change of round trip time in the optical fiber laser resonator. While the round trip time is the reciprocal of the minimum beat frequency, the group delay of the optical fiber under test which is placed in the fiber laser resonator can be easily obtained by measuring the beat frequency variation via the radio frequency spectrum analyzer. The optical fiber laser resonator utilized in experiments is composed of two reflectors: one is a sagnac loop composed of a coupler, the other is a composite structure composed of an optical circulator connected with a Fiber Fabry-Perot Tunable Filter. The group delay of the single-mode fiber and the dispersion compensating fiber are measured respectively in a relatively wide spectral range. Experimental results show that this method is feasible. Furthermore, this method is of very simple structure and low cost compared with other conventional methods. [ABSTRACT FROM AUTHOR]

ABSTRACT The inverse Legendre filter response is derived and its property is analysed by providing the magnitude specifications in the passband and stopband. The inverse Legendre function requires the identical order n as its Legendre counterpart. A quantitative comparison is carried out between Chebyshev, inverse Chebyshev, Legendre and inverse Legendre to show the improved characteristics of the inverse Legendre filters depending on specifications and criteria. The inverse Legendre filter shows maximally flat characteristic in the passband and in comparison to other filters, it exhibits improved group delay characteristics. Finally, the filter is implemented in microstrip low pass configuration and a prototype model of the proposed filter configuration is developed and measured. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:69-73, 2017 [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, a circular loop antenna with stable broadside radiation characteristics for ultrawideband (UWB) applications is proposed. It consists of a circular loop and circular sectors, and the circular sectors are used to directly match a 50-Ω feed line over a UWB frequency band. The geometry of the proposed antenna is optimized to cover the 3.1-10.6 GHz UWB frequency band with stable broadside radiation patterns. The input impedance and voltage standing wave ratio (VSWR) characteristics of three different structures (a center-fed circular loop with thin strips, a structure with circular sectors as an end-truncated semicircular dipole, and the proposed loop antenna with circular sectors) are compared. The optimized proposed antenna is fabricated on a Teflon substrate. It exhibits a measured impedance frequency band of 3.08-12.27 GHz (120%) for a VSWR < 2, which ensures operation in the UWB band. Measured broadside gain is 3.0-7.0 dBi, and stable broadside radiation patterns are observed in the entire UWB band. Measured group delay remains almost constant with a variation of less than ±0.5 ns for the face-to-face orientation, and this indicates good time domain performance of the antenna. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2515-2519, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT A low-noise figure (NF) and high power gain (S21) 3-10 GHz ultrawideband low-noise amplifier (UWB LNA) with excellent phase linearity using standard 0.18-µm CMOS technology is reported. An enhanced π-match input network is used to achieve wideband input impedance matching. Both high and flat S21 and low and flat NF frequency responses are achieved by tuning the pole frequencies and pole quality factors of the second-order gain and NF frequency responses to approximate the maximally flat condition simultaneously. The LNA consumes 18 mW, achieving S11 better than −10 dB for frequency lower than 12.2 GHz and group-delay-variation smaller than ±14.6 ps for frequencies 3-10 GHz. Additionally, high and flat S21 of 13.7 ± 1.5 dB is achieved for frequencies 1-12.5 GHz, which means the corresponding 3-dB bandwidth is 11.5 GHz. Furthermore, the LNA achieves minimum NF of 2.2 dB at 4 GHz and NF of 2.3 ± 0.1 dB for frequencies 3-10 GHz, one of the best NF results ever reported for a 3-10 GHz CMOS UWB LNA. The measured input third-order intermodulation point (IIP3) is −0.2 dBm at 6 GHz. The chip area is only 0.601 × 0.662 mm2 (i.e., 0.4 mm2) excluding the test pads. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2047-2053, 2014 [ABSTRACT FROM AUTHOR]

ABSTRACT A novel compact coplanar waveguide-fed antenna is presented with triple band-notched characteristics. A C-slot is etched in a novel patch to avoid interference from WiMAX band. By using pair of CSRR slots and pair of L-shaped slits in ground plane, two notched bands for WLAN and ITU 8 GHz bands are obtained, respectively. The antenna has bandwidth of 2.8-11.2 GHz with three notched bands of 3.3-3.7 GHz, 5-6 GHz, and 8-8.4 GHz to avoid interference from WiMAX, WLAN, and ITU 8 GHz bands, respectively. The antenna has good impedance matching and stable radiation patterns. Good agreement is reached between measured and simulated results. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2113-2117, 2013 [ABSTRACT FROM AUTHOR]

A novel ultra-wide band planar antenna with dual band-notched characteristics is presented in this article.The antenna has compact size of 23 × 28 × 0.8 mm3 and it consists of novel patch. The measured antenna has impedance bandwidth of 3-10.7 GHz with dual notched bands of 3.3-3.7 GHz and 5.1-5.9 GHz to avoid interference from WiMAX and WLAN bands, respectively. A set of spiral slots and novel pulse-shaped slots are etched in ground plane to obtain the dual notched bands. The effects of different geometrical parameters on various characteristics of antenna are investigated. The proposed antenna has consistent gain and stable radiation pattern. The measured group delay indicates that the antenna has good time domain response.© 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:740-744, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27461 [ABSTRACT FROM AUTHOR]

A miniaturized planar ultra-wideband (UWB) antenna is proposed.The antenna is fed with a tapered microstrip line. A trapezoidal ground pattern is studied to improve impedance matching over the UWB frequency range. The total size of proposed antenna is 22 × 25 mm2, which is much smaller than the antenna with a conventional square ground. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2468-2472, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27148 [ABSTRACT FROM AUTHOR]

Design features of a reduced size coplanar waveguide (CPW) fed ultra wide band (UWB) taper arc wide slot antenna with impedance Band Width (BW) of 9.69 GHz have been illustrated. The antenna depicts satisfactory performance both on free space and when immersed in three different coupling materials for application in the experimental MI set up. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2607–2611, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24701 [ABSTRACT FROM AUTHOR]

In this article, we have proposed a dual-band antenna with U-shaped open stub for wideband local area network (WLAN)/ultra wideband (UWB) applications. The designed dual-band antenna consists of two semicircle radiating patches, a rectangular slot separating the two semicircles, one step for impedance matching, and coplanar waveguide (CPW) feeding. Two kinds of prototypes (CPW-fed UWB antenna and the dual-band antenna with U-shaped open stub) are fabricated and measured. Parametric studies and radiation characteristics for the two antennas are presented. The designed antenna has the figure-of-eight radiation pattern, wide bandwidth, and negligible dispersion over the operating frequency band. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 284–289, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24033 [ABSTRACT FROM AUTHOR]

A diamond-shaped compact, planar ultra-wide band (UWB) antenna with measured free-space frequency bandwidth of 3.80 to 11.85 GHz is presented. Design features for achieving UWB with small geometrical features and antenna performance in some coupling medium have been investigated to verify the feasibility of the antenna for medical imaging applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3255–3259, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23941 [ABSTRACT FROM AUTHOR]

We have proposed a compact filter-combined ultra-wide band antenna for the use of DS-UWB low band or MB-OFDM lower three bands (3.1–5.2 GHz). The designed antenna has a microstrip-fed trapezoidal radiating patch, UWB band pass filter using the dumbbell-shaped DGS (defected ground structure), and IDC (interdigital capacitor): two steps for impedance matching, and microstrip feeding. Three kinds of prototypes (trapezoidal UWB antenna, UWB band pass filter, and the compact filter-combined ultra wideband antenna) are fabricated and measured. The designed antenna has the figure-of-eight radiation pattern, wide bandwidth, and negligible dispersion over the operating frequency band. Details of the proposed antenna design and the simulated and measured results are presented and discussed. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2839–2845, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23839 [ABSTRACT FROM AUTHOR]

In this article, we have described a novel ultra-wideband (UWB) monopole antenna with two symmetrical strips for wireless UWB communications. The proposed antenna consists of a center monopole, two symmetrical strips having one step on the strip, and CPW feeding. Three techniques (one monopole and two strips, symmetrical structure, and step on the strip) are used to produce the multiple resonance and low dispersion. The proposed UWB antenna has an omnidirectional radiation pattern, UWB, compact size, almost flat gain and linear phase, and low cost. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2845–2848, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23838 [ABSTRACT FROM AUTHOR]

Based on linear-system theory, a method to obtain the total group-delay characteristics of the cascaded chirped fiber Bragg grating (FBG) from the measured group delays of each grating is proposed. The method is then used to characterize cascaded chirped FBGs used as the dispersion compensators of an experimental eight-channel 10-Gb/s NRZ system over 1500-km G.652 fiber. The inband total local-dispersion deviation curve is calculated and shows good consistency with the tendency of the inband BER fluctuations, which indicates that the inband local dispersion deviation may be the main reason for the dependence of such a system performance on signal wavelength, and its RMS value can be taken as the indicator of performance tolerance to wavelength instability. Numerical simulation is also performed, by which a near linear scaling of the simulated EOP with total local-dispersion deviation is shown. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 343–346, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21165 [ABSTRACT FROM AUTHOR]

A novel ultra-wideband (UWB) antenna fed by coplanar waveguide (CPW) is designed, fabricated, and measured for UWB communications. It is designed to work on a substrate TMM4 of thickness 0.762 mm and relative permittivity 4.5, and to operate from 3.1 to 8.3 GHz. Details of the proposed antenna design and the measured results are presented and discussed. Measured insertion loss is almost constant across the frequency band and the group-delay variation is less than 1 ns, thus indicating that the proposed antenna is a good candidate for UWB applications. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 393–396, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20646 [ABSTRACT FROM AUTHOR]

In this paper, an analytical analysis is made on a periodic bandpass filter formed by a two-cavity etalon incorporated into a Sagnac loop interferometer. The general optimum conditions for a quasi-flat-top spectrum and a ripple-free group-delay response are derived. Our results show that by properly choosing the reflectance of the mirrors, the filter can be designed with a quasi-flat-top spectral response that is also free from group-delay ripples. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 17–21, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20194 [ABSTRACT FROM AUTHOR]

In the present paper, the results of theoretical investigations of a lens' dispersion characteristics and the field intensity of propagated through a lens spatial-limited femtosecond pulses with a duration of several optical periods are presented. The dependences of group delay and group velocity dispersion that are introduced by the lens versus spatial coordinates and frequencies are obtained. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 302–305, 2001. [ABSTRACT FROM AUTHOR]

When the center frequency of a microwave pulse is tuned across the spectral range of a photonic bandgap (PBG) structure implemented in microstrip technology, the group delay introduced varies widely from high values to strikingly small values that give rise to superluminal propagation effects. In this paper, we explore this phenomenon, showing that the same behavior as for optical PBG devices is achieved. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 23: 346–349, 1999. [ABSTRACT FROM AUTHOR]

We measure a maximum group delay of 22.6 ps for a light pulse propagating through a 1 cm long fiber Bragg grating when the frequency of the light is tuned near the band edge of the grating. Our measurements are performed in the time domain with single picosecond resolution using wavelength-tunable pulses of 0.5 nm bandwidth spectrally sliced from a mode-locked laser. Our experimental results are qualitatively confirmed by our numerical simulations. Promising applications include optical delay elements for phased-array radar and encoders/decoders in spread-spectrum code-division multiple-access systems. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 17–21, 1999. [ABSTRACT FROM AUTHOR]

Resonator coupled filters can be designed and tuned in terms of the group delay of the reflection coefficient. This group delay is an effective way to measure the filter parameters and set them to the precise values to generate a specific response. The basic method was outlined previously, but this was restricted to in-line coupled resonators. In this paper, the method is expanded to include parallel and cross-coupled resonators, and the effect of finite Q of the resonator is analyzed in more detail. Finally, some comments on the meaning of the group delay measurement and the possibility of a negative delay are discussed. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 18: 174–179, 1998. [ABSTRACT FROM AUTHOR]

In this paper, we present a compact, tunable delay line based on left-handed nonlinear transmission line (LH NLTL). The widely tunable range of the large group delay is achieved by controlling a reverse bias voltage of series varactors in the LH NLTL. The proposed tunable delay line can be made in a very compact form because its size is dominated by the cascaded varactors. Our experiment shows that the fabricated prototype exhibits tunable group delay between 1.2 and 2.2 ns at a frequency of 1.42 GHz and good return loss. The circuit size is merely 1.6 cm in length. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2893–2895, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24747 [ABSTRACT FROM AUTHOR]

A planar structure of group-delay equalizer, which is built on high temperature superconducting (HTS) films, is proposed in this article. The HTS equalizer consists of one microstrip 3-dB hybrid and two identical 1-port coupled-resonator filters. Compared with the traditional equalizers composed of cavity or coaxial resonators, the HTS equalizer has the advantages of smaller insertion loss and smaller size. As an example, a 3-pole HTS equalizer is designed to equalize a 6-pole HTS filter and good performance is achieved. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2163–2165, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22681 [ABSTRACT FROM AUTHOR]

In this paper, we propose a frequency-notched ultra-wideband (UWB) slot antenna. The proposed antenna can cover the entire UWB band and the IEEE 802.11a frequency band can be notched out by inserting a hat-shaped slot into the antenna. The path loss |S21| and group delay are measured and discussed. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 105–107, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21276 [ABSTRACT FROM AUTHOR]

In this paper, we propose a new ultra-wideband (UWB) antenna for UWB applications. The proposed antenna is designed to operate from 3.2 to 12 GHz. It consists of a rectangular patch with two steps, a single slot on the patch, and a partial ground plane. Details of the proposed antenna design and measured results are presented and discussed. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 399–401, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11392 [ABSTRACT FROM AUTHOR]

We present a novel fiber grating measurement technique based on the direct modulation of a tunable laser source by an optical component analizer (COA). © 1997 John Wiley & Sons, Inc. Microwave Opt Technol Lett 14: 373–375, 1997. [ABSTRACT FROM AUTHOR]