Method of generating negative group delay in phase arrays without using lossy circuits

Alomar, Waleed A.; Mortazawi, Amir

doi:10.1109/ieee-iws.2013.6616774

Cited by 23 publications

(25 citation statements)

References 11 publications

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“…12 In addition, the NGDC can also be used in array antennas to eliminate the beam squint and achieve flat gain. 13,14 Although the NGDC consisting of the RLC resonant circuit has advantages mentioned above, its application is limited by the instability and frequency dependence of the capacitors and inductors. In order to reduce the effect of the lumped elements, the NGDCs based on distribution parameters have been attracted more attention.…”

Section: Introductionmentioning

confidence: 99%

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Group delay flatness and bandwidth enhancement of wideband negative group delay microwave circuit

Meng

Wang

Fang

et al. 2020

Int J RF Microw Comput Aided Eng

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A wideband negative group delay (NGD) microwave circuit with group delay flatness and bandwidth enhancement is proposed. The proposed negative group delay circuit (NGDC) is composed of a resistor connected by two transmission lines and a parallel branch consisted of a resistor linking with a stepped-impedance transmission line and two open stubs. By tuning the characteristic impedance of the transmission lines, the flat-NGD bandwidth is enhanced. For verification, an NGDC with a size of 0.24λ g × 0.34λ g is designed, fabricated, and measured. The measurement shows that an NGD time of −0.5 ns at the center frequency of 1.0 GHz is obtained with the NGD bandwidth of 68.6% over 0.668 to 1.365 GHz. Also, the flat-NGD bandwidth reaches 46.3% or 0.776 to 1.243 GHz with ±8% group-delay fluctuation while the insertion loss is less than 18.8 dB and return loss is greater than 21 dB.

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Section: Introductionmentioning

confidence: 99%

“…Except for the utilization of the NGDC in amplifier, the NGD active circuits can be used in phase shifters to broaden flat phase shift bandwidth and remain the group delay as zero 12 . In addition, the NGDC can also be used in array antennas to eliminate the beam squint and achieve flat gain 13,14 …”

Section: Introductionmentioning

confidence: 99%

Group delay flatness and bandwidth enhancement of wideband negative group delay microwave circuit

Meng

Wang

Fang

et al. 2020

Int J RF Microw Comput Aided Eng

View full text Add to dashboard Cite

show abstract

“…So far, few research groups work on the NGD function applications particularly, in the microwave engineering area. Recently, the NGD function was used for the improvement of microwave device performance as array antenna system, phase shifter, and feedforward amplifier . The signal and group delay effects limit the performances of RF/microwave communication devices and systems .…”

Section: Introductionmentioning

confidence: 99%

Tee power divider and combiner based negative group delay topology

Ravelo

2018

Int J RF Microw Comput Aided Eng

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An innovative topology of negative group delay (NGD) microwave circuit based on the interconnected power divider and combiner (PWD/PWC) is investigated. The distributed cell consists of PWD and PWC with the input and outputs interconnected by a transmission line (TL). The theory is based on the S‐parameter modeling. The NGD existence condition is formulated. The NGD properties constituted by the NGD bandwidth, level and figure of merit are introduced. It is shown that the distributed topology behaves as a bandpass NGD circuit. The NGD topology theoretical efficiency is verified with simulations by considering NGD circuit parametric analyses by varying the PWD‐PWC interconnect TL attenuation. To validate experimentally the NGD concept, two prototypes of one‐ and two‐stage passive NGD cells were designed in microstrip technology, fabricated and tested. The one‐ and two‐stage circuit prototypes exhibit NGDs of about −2.2 ns and −4.7 ns with −3.4 dB and −7.5 dB insertion loss, respectively. The NGD phenomenon was generated around 1.85 GHz‐center frequency over about 35 MHz‐NGD bandwidth.

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“…Despite this impressive reduction time delay technique, the meaning and existence of the NGD effect at the microwave frequency were becoming an open-question. To understand this intriguing phenomenon, experimental investigations on the NGD phenomenon existence in the S-band frequency range were conducted [17,18]. At the beginning, this particular phenomenon was empirically observed with a complex frequency synthesiser device [17].…”

Section: Introductionmentioning

confidence: 99%

X‐band negative group‐delay lossy stub line

Ravelo

2017

IET Microwaves, Antennas & Propagation

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This study investigates the negative group delay (NGD) passive circuit constituted by a fully distributed parallel stub line. The proposed S‐parameter modelling is developed. The transmission parameter band‐pass NGD function identification is described. The NGD characterisation is established by determination of the NGD level and bandwidth in function of the stub line parameters. It was analytically found that with a basic cell consisted of single stub line, the insertion loss is usually degraded to reach significant figure‐of‐merit which is obtained with the NGD level‐bandwidth product. As a solution, it is shown that this insertion loss can be improved with the consideration of matching network. As proof‐of‐concept (POC), microstrip distributed circuits printed on the flexible Kapton substrate without lumped element were synthesised, designed and fabricated. The theoretical, simulated and measured results are in good correlation. As expected, band‐pass NGD behaviours centred beyond 10 GHz were observed. The POC generates NGD level of about −1.5 ns over the NGD bandwidth 0.65 GHz. In the future, thanks to the theoretical approach simplicity and the topology integrability, the NGD principle can be potentially useful for the improvement of RF/microwave circuits.

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Method of generating negative group delay in phase arrays without using lossy circuits

Cited by 23 publications

References 11 publications

Group delay flatness and bandwidth enhancement of wideband negative group delay microwave circuit

Group delay flatness and bandwidth enhancement of wideband negative group delay microwave circuit

Tee power divider and combiner based negative group delay topology

X‐band negative group‐delay lossy stub line

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