# Hybrid Mode Reconfigurable Antenna with V-Shaped Extrudes for Cognitive Radio Applications
## 1 Introduction
Regarding a frequency-reconfigurable MIMO antenna, the projected MIMO antenna comprises two switchable, printed monopole designs connected by electrodes and an isolation enhancement design positioned in the middle of the two antennas. P-I-N diodes are mounted onto the radiator in order to modify the operating frequency. The resonant frequency switches between the WiMAX band and the WLAN band (2.400-2.483 GHz and 5.150-5.350 GHz), dependent upon the switching state of the P-I-N diode (3400-3600 MHz). [20]. The compact, multi-band antenna discussed can be used for mobile devices and WLAN [21; 22]. The E-shaped microstrip antenna is a new single-patch, wide-band microstrip antenna. A microstrip antenna's patch has two parallel slots built into it to increase its bandwidth [23]. A multi-band switchable bowtie slot radiator with switchable aperture couples is discussed. An antenna that is reconfigurable in frequency, has a high realised gain, and operates in WiFi, WLAN, and WiMAX with four functioning modes--one with all in single band, another two with a double band, and one with three bands--was developed using the attributes of the bowtie antenna. With respect to operation frequency, the antenna's radiation pattern remains unchanged [24]. A brand-new flexible, wearable dual-band antenna that can work in WLAN applications at 2.4 and 5.8 GHz is demonstrated. Two printed monopole components make up the planned antenna, which is based on a unique analytical geometric curve produced by an exponentially declining sinusoidal profile [25]. The prototype of the device was made using the inkjet printing technique with a flexible polyethylene terephthalate substrate. The antenna surface incorporates a single p-i-n diode to reroute and distribute the surface current, creating a polarization- and frequency-adjustable antenna. When the switching diode is in ON mode, the designed antenna results in only one band for WLAN applications at 2.42 GHz. After the switching diode is set to OFF mode, the designed antenna provides two bandswith dissimilar polarizations for WLAN at 2.36 GHz and for WiMAX at 3.64 GHz [26]. This research examines a multi-band, reconfigurable antenna that is small and flexible. The suggested antenna is suitable for 5.6 GHz WLAN, 3.8 GHz 5G NR, and for Bluetooth applications at 2.4 GHz. In order to cover the WLAN, Bluetooth, and 5G NR frequency bands, the antenna uses monopole patches, inverted L-shaped monopoles, and F-shaped monopoles [27]. An antenna of this type is designed using a patch antenna that has been concentrically shorted using a number of conductive vias. To analyse the antenna, a cavity model is used. The cavity model identifies each resonating mode, offers physical insight through each antenna mode, and offers design recommendations for a wideband monopolar antenna with two modes, TM01 and TM02. Both modes produce a radiation pattern that resembles a monopole. The suggested structure includes a 0.024 wavelength profile, a simple structure, and an impedance bandwidth of approximately 18% which provides a maximum gain of 6 dBi. A pattern-reconfigurable antenna with H-shaped elements precisely positioned on both faces of a dipole to guide power flowing in the end-fire direction is shown [28]. A low-profile, annular, slotted microstrip antenna with circular polarisation and frequency-configurable features was discussed [29]. A U-shaped aperture with short ends and an L-shaped slot with open terminals carved in the metallic ground plane of a compacted, frequency-reconfigurable slot design is useful for LTE, WLAN, and AMT fixed-service applications. By placing two P-I-N diodes into the slots, switching for three frequency bands over a 2.62:1 frequency ratio was accomplished. An additional L-shaped aperture was symmetrically added to an antenna to less cross-polarisation [30]. Here, the circularly polarized operation was accomplished by activating dual orthogonal modes with varying resonance frequencies, and frequency switching was obtained using capacitive loading [31].