## 1 Introduction
In [20], a narrow-band filter using bandpass technology is implemented where negative resistance is used to increase the selectivity and the 3 dB bandwidth of the filter is less than 1%. In [21], the FR4 and Arlon 25N substrates are used in the development of a bandpass filter that makes use of a hairpin resonator structure and operates at a centre frequency of 2.1 GHz. The bandwidth of the filter is 400 MHz, the insertion loss, measured in decibels (IL), is less than 2.5, whereas the return loss, measured in decibels (RL), is greater than 20. A parallel inductive switch network (PISN) is used to make a re-configurable filter bank with a wide range. Three filters are designed on a single substrate using the lumped element method. Inductive switches that are inductive PIN diodes are used to switch between different frequency filters [22]. Coupled line resonators are used to design a filter bank with three filters from 18 to 40 GHz. MMIC switches are used to switch between the filters. The insertion loss is approximately 12 decibels, whereas the return loss is greater than 60 decibels [23]. A perfect decomposition narrow-band finite impulse response filter bank is designed [24]. The frequency range of this filter bank-based RF transceiver ranges from 470 MHz to 698 MHz. In [25], ceramic resonator technology is used to design four bandpass filters. Dual passband microstrip-based stepped impedance resonators are designed at 2.14 and 4.33 GHz [26]. A tunable filter with 13% relative bandwidth and a frequency range of 18.5 to 21.05 GHz is designed using tapped line feedings. MEMS capacitors are used as capacitive switches [27; 28]. The switched filter bank consisting of four filters in the S and C frequency bands is designed using the quarter-wave and stepped impedance technique. MEMS switches are used for switching purposes and switching is controlled using an Atmega-328p controller [29]. An electronically tunable filter is designed at a tunable range of 700 MHz to 1.33 GHz with an insertion loss less than 2 dB. The filter is implemented on a suspended substrate [30; 31]. Surface acoustic wave (SAW) bandpass filters are fabricated on a low-temperature co-fired ceramic (LTCC) substrate for ISM band frequency and the insertion loss (IL) is less than 1.5 dB [32]. In [33], two bandpass filters are designed and switched using PIN diodes at the center frequency of 1.955 GHz with 140 MHz bandwidth and at 2.44 GHz with 80 MHz bandwidth. Bandpass microstrip filters are used to reduce harmonics in 5G networks [34; 35]. For switching, components like PIN diodes and capacitors are used [36; 37; 38]. Three pole bandpass filters are designed using microstrip lines on an alumina substrate. An SP3T MEMS switch is employed for switching between filters. The passband range is 14 GHz to 18 GHz, the insertion loss of all filters is less than 2 dB, and return loss is more than 10 dB [39]. Using ohmic and capacitive switches, a unique SP4T RF MEMS device is suggested in [40]. It is made with a silicon substrate with a 1 mm\({}^{2}\) surface area. This RF switch features an excellent X-band insertion loss of less than 0.7 dB between each port and a strong isolation of 70.64 dB overall. In [41], the notch band is created using resonators coupled to bandpass filters with a stepped impedance resonator. In [42], innovative C-band wide band stop filter topologies with a simplified microstrip implementation are given. As shown in Figure 1, the switching filter bank is proposed for use with narrow-band filters to increase sensitivity and noise. However, these filter banks require manual operation. If the target's frequency changes while you are manually monitoring it, the receiver system is unable to keep up, since someone must constantly adjust the system's frequency to match the target's new frequency.