Compact UWB‐to‐C band reconfigurable filtenna based on elliptical monopole antenna integrated with bandpass filter for cognitive radio systems

Abstract

In this study, a compact configuration of frequency reconfigurable filtenna, designed by integrating a bandpass filter and with a monopole radiator, is demonstrated for achieving high‐frequency selectivity along with compact size. The proposed filtenna can be efficiently tuned between ultra‐wideband (UWB) and C‐band states of operation. A bandpass filter, based on rectangular stepped impedance stub loaded multiple‐mode resonator (MMR), is embedded to an elliptical monopole radiator to construct the filtenna circuit. The filtenna design approach leaves out the necessity of cascading an additional 50 Ω microstrip feed line in between the antenna and filter elements which makes the system more compact. The designed filtenna occupies 3.6–10.6 GHz band in its UWB state of operation and 3.63–4.70 GHz band in its C‐band state of operation, respectively. The UWB operating state is intended for spectrum sensing application whereas the C‐band operating state can be implemented for communication in a cognitive radio environment. The shifting between two operating states is controlled by appropriately switching the PIN diodes. An average peak gain of 2 dBi is observed within the passband. The overall size of the filtenna is optimised to 1.35λ0 × 0.96λ0 × 0.04λ0 (λ0 is calculated at 6.85 GHz). For validation purpose, the filtenna prototype is fabricated and characterised. A very close agreement is achieved with the suggested configuration.

A Miniaturized UWB Bandpass Filter Employing Multi-Stub-Loaded Short-Circuited Stepped Impedance Ring Resonator

“…While these filters offer a sufficiently broad stop band, there are a few issues, including a big circuit size and a significant insertion loss. A multimode resonator (MMR) that has a rectangular stepped impedance stub, two open-circuit stubs, and two high-impedance lines for input and output feeders is used to create the UWB filter [6]. A novel MMR made of interdigital-coupled lines that are cascaded and stepped impedance stubs that are loaded with short circuits is also suggested in [7], and UWB filters may be created by implementing it further.…”

Ultrawide band cage dipole antenna for ultra high frequency band ground penetrating radar system

“…21 The authors have also designed and demonstrated reconfigurable filtenna using elliptically shaped monopole integrated with multimode resonator-based bandpass filter. 22 The proposed antenna is integrated with a PIN diode, which enables the switching between UWB and C-band. However, the pulse radiating characteristics is not evaluated for such structure, which is the primary requirement for UWB antenna for GPR application.…”

Fully tunable filter‐antenna with microstrip and quarter‐mode substrate‐integrated waveguide hybrid structure

“…1 In the mainstream tunable filter-antenna research field, CF tunability is the main research direction. [1][2][3][4][5][6] In References 1-3, the tuning of the CF is achieved by switching P-I-N diodes in different frequency bands, which is not continuously tuned. In order to meet the continuous CF switching requirements in the agile transceiver antenna system, the continuous CF tunable filter-antenna has also become an important direction in tunable research.…”

“…In the mainstream tunable filter‐antenna research field, CF tunability is the main research direction 1‐6 . In References 1‐3, the tuning of the CF is achieved by switching P‐I‐N diodes in different frequency bands, which is not continuously tuned.…”