Ultra‐wideband technology has experienced a rapid growth over the last decade for its contribution in different sectors of human society. Printed antennas are considered as preferred platform for implementing this technology because of its alluring characteristics like light weight, low cost, ease of fabrication, integration capability with other systems, etc. Antennas developed for ultra‐wideband applications are desired to have notch characteristics for avoiding interference with other existing radio communication systems. The techniques related to design and developments of printed band‐notched antennas are continuously upgraded for improving the antenna performance. In this article, a comprehensive review has been carried out on ultra‐wideband antennas with band notch characteristics proposed in around last decade. The band notched UWB antennas available in the literature have broadly been classified into five different categories based on their notch characteristics like single band‐notch, dual band‐notch, triple band‐notch, quad/multiple band‐notch, and reconfigurable/tunable band‐notch, respectively. This review exercise may be helpful for beginners working on ultra‐wideband band‐notched antennas and also such a review process is not available in the open literature to the best of author's knowledge.

This article introduces a compact configuration of printed monopole antenna with electronically tunable band‐notched function for ultra‐wideband (UWB) applications. A partially grounded rectangular shaped monopole is designed initially to achieve UWB behavior. The notch characteristics are then introduced by employing three complementary split‐ring resonators (CSRRs) on the radiating surface. The proposed antenna exhibits an ultra‐wide operating band ranging from 1.98 to 10.54 GHz with the notched frequencies at 2.37, 3.03, and 4.18 GHz, respectively. In order to accomplish versatility in the antenna operation, the notched frequencies are controlled electronically by implementing three varactor diodes in between the split‐ring slots. By applying an appropriate reverse bias voltage, the triple notched bands are tuned over the frequency bands: 1.58‐2.12 GHz, 2.24‐2.68 GHz, and 3.08‐3.78 GHz, respectively. A prototype with an overall dimension of 34.9 × 31.3 × 1.6 mm3 has been fabricated to experimentally determine the tuning capability of the antenna structure. The experimental result establishes close correspondence with the simulated antenna properties. The suggested antenna can be implemented practically to reject interferences from complete 1.5‐2.1 GHz LTE systems, and 2.5/3.5 GHz‐WiMAX bands, simultaneously. The capability of tuning three notched‐bands together is distinctive and has not been reported in the published literature to the best of authors' knowledge.

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This paper aims to present a highly selective, compact size new ultra-wideband (UWB) bandpass filter with three sharp notches for UWB indoor applications. The fundamental geometry of the filter is based on a modified multi-mode resonator (MMR) structure which comprises an open-ended step impedance resonator (SIR) attached to an interdigitated uniform impedance resonator (UIR). Realizing a Comb-shaped resonator structure below the UIR and symmetrically extending the lower arm edge of the interdigital coupled lines, three notches are generated at 6 GHz, 6.53 GHz, and 8.35 GHz. These notches have improved the UWB bandpass filter responses by suppressing the existing interferences in the UWB passband created by Wi-Fi 6E (6 GHz), super-extended C band (6.425 GHz ∼ 6.725 GHz), X band satellite communications for satellite TV networks or raw satellite feeds (7.25 GHz ∼ 8.395 GHz). Concurrently the notched band filter has achieved superiority in other salient features concerning passband and stopband of the filter such as a high passband fractional bandwidth (115.76%), low return loss (−13.27 dB), low insertion loss (0.44 dB ∼ 0.97 dB), wide upper stopband (5.37 GHz), nearly flat group delay (0.28 ns ∼ 0.45 ns), etc. The ultimate design of the UWB bandpass filter is fabricated and verified by comparing the simulated filter responses with the measured results indicating a good agreement.

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