Description:Field of Invention
The present invention relates to Ultra wide band (UWB) antenna for radar detection application. More particularly, the present invention relates to the Ultra wide band (UWB), it is a radio technology that allows for the short-range, extremely low-power transmission of massive amounts of data over a wide frequency band. A breakthrough method of wireless communication is ultra wide band radio transmission that it sends and receives compressed time-domain wave forms based on pulses rather than standard radio transmission in the frequency domain.

The objectives of this invention
The objective of this invention is to design an antenna that can be used over the whole UWB frequency spectrum. Physically small, flat, and inexpensive to manufacture are all desirable characteristics for an antenna. To successfully transmit and receive sub-nanosecond pulses, the antenna must also have good electrical performance, including good impedance matching, directional radiation performance over the entire UWB range, and most importantly, good time response. To create one and two dimensional motion tracking applications, the antenna needs to be directional enough to work with Novelda AS R2A radar chips.

Background of the invention
The word "ultra-wideband" can refer to radio or radar transmissions with a wide relative bandwidth as well as impulse, carrier-free, baseband, and other comparable terms. Ultra-wideband technology is not a brand-new idea. The initial UWB spark Gap radio was pulse-based.
Guglielmo Marconi created a device in the late 1800s that transmitted Morse code for a long time. However, it was prohibited to use these radios in early 1900 because due to their powerful power emission and interference with other devices, they have numerous applications. Early in the 1900s, narrow band radio systems were established. UWB technology attracted a lot of attention in the late 1960s due to its application as impulse radar in the military. The prototype of the antenna was fabricated and tested in real time and the resultant wasfound to be correlated with the measurement results(Amutha Muniyasamy,et.al, [2019],InternationalJournal of Electronics and Communications, 99,pp.369-375).Researchers put a lot of work into researching many areas of ultra-wideband technology at this time. The first time domain instruments for sub nanosecond pulse diagnostics were created in 1964 by Hewlett Packard and Tektronix Inc., which represented a significant advancement in UWB system design. The designed AVA exhibits satisfactory characteristics such as small size,
fractional bandwidth, and low cross-polarization of less than -15 dB and maximum return loss of -31 dBat an operating frequency of 7.368 GHz(Dvorsky, et.al., [2019], International Journal of Antenna andWave Propagation,2019).Antenna designers including Ross, Rumsey, and Dyson have begun developing antennas for UWB systems. Wideband radiating antenna elements were designed by Ross using impulse measuring techniques, while Rumsey and Dyson created logarithmic spiral antennas.

Detailed of Prior Art
This is a continuation of earlier work completed in the Imego AB UWB Radar Application Project, a company with extensive expertise in sensor technology. The Novelda AS R2A CMOS radar chips serve as the foundation for the Imego UWB radar application project, which was initiated in January 2008. Any UWB radar application needs an antenna to function. The main goal is to create an antenna that can be used over the whole UWB frequency spectrum. Physically small, flat, and inexpensive to manufacture are all desirable characteristics for an antenna. To successfully transmit and receive sub-nanosecond pulses, the antenna must also have good electrical performance, including good impedance matching, directional radiation performance over the entire UWB range, and most importantly, good time response. To create one- and two-dimensional motion tracking applications, the antenna needs to be directional enough to work with Novelda AS R2A radar chips. The invention provides a wave form design method for an ultra-wideband radar, which is distinguished by the fact that, based on prior knowledge of clutter, an energy distribution mode facing clutter suppression is designed in an ultra-wideband frequency domain, improving the radar's ability to detect and identify targets against a clutter background and suppressing the radar's response energy to the clutter when the instantaneous clutter is present.(CN110471034B). An executable program is kept on a non-transitory computer readable storage device in one embodiment. A series of chirps will be transmitted by the millimeter-wave radar sensor inside its field of view, according to the executable program's instructions. based on radar information gathered by the millimeter-wave radar sensor and in response to the transmission of the series of chirps, identify a group of targets inside the field of vision; filter the radar data to produce a signal that has been first filtered. (US10775493B2).

Summary of Invention
The main goal of this research is to create an antenna with good directional radiation performance that can operate across the whole UWB frequency range. High efficiency, wide bandwidth, light weight, small size, and simplicity are important criteria for such an antenna.Although the majority of directional wideband antennas, including Horn and log periodic array antennas, offer strong directivity, their non-planar construction and large size make them unsuitable for use in UWB radar chip applications.

Detailed description of the invention
A two-dimensional slot antenna is the antipodal Vivaldi antenna. When creating an antipodal Vivaldi antenna, a slot transmission line that spreads out to create horn-shaped radiating elements is gradually used in place of a microstrip transmission line. The inner and outer margins of the slot line conductors in the antipodal Vivaldi radiator are exponentially tapered to create an antipodal Vivaldi antenna. The feeding transition and tapered radiating slot make up the antipodal Vivaldi antenna. Two arms printed on opposing surfaces of a dielectric substrate provide the symmetric tapered radiating slot. The ground trace is exponentially tapered, however the feeding transition consists of a 50 microstrip line exponentially tapered to a parallel strip line to feed the tapered slot radiator. The antenna is small in size and has an opening slot that is exponentially tapered to produce one-way directivity. Two exponentially tapered arms that are positioned on the opposing sides of the substrate make up the antenna's radiating structure. The 50 Microstrip feed linked to the top arm by the exponentially tapered arms A 50 microstrip line supplies an arm that is exponentially tapered and connected to the lower arm to improve impedance matching over a wide bandwidth. To provide impedance matching across the whole UWB range, an exponentially tapered ground plane feed is connected to the tapered arm on the substrate's bottom layer.

At the micro strip feed, the ground plane feed is at its narrowest before expanding exponentially on all sides. According to antenna geometry, the XY plane (?=90°) is an E-plane, whereas the YZ plane (F=90°) is an H-plane, and the direction of the antenna's maximum emission is along the Y-axis (?=90°,F=90°).The antenna's structure now includes a transition. This is necessary because the radiating part of the antennais linked to a parallel strip line, a balanced transmission line, as opposed to the coaxial cable that will be used to connect the antenna to the UWB radar chip, an unbalanced transmission line. The microstrip line is connected to the parallel strip line at the top layer using a tapered transmission line, and the bottom layer's parallel strip line's width is gradually extended to create the necessary ground plane.To determine the ideal values for the antenna's various parameters, HFSS simulations of a variety of different scenarios were run.
A "surface-type" traveling-wave antenna is an antipodal Vivaldi antenna. The waves move along the antenna following the flare's bent path. The waves are closely confined in the region where the distance separating the two conductors is close to the wavelength of free space. The link weakens more and more with increasing distance, and the waves radiate away from the antenna. This happens when the edge separation exceeds 0.5 wavelength. Impedance match is a fundamental parameter used to characterize the impedance bandwidth of an antenna.
The sharp nulls in the plot correspond to the frequencies that attain the highest resonance. These points indicate a near perfect match to 50 O.
A UWB antenna should ideally have a linear phase response. With the exception of strong phase changes at around 4.5 and 6.5 GHz, which are clearly caused by the antenna being more resonant at these frequencies than at other frequencies in the given frequency range. The derivative of radian phase with respect to radian frequency is known as group delay. If there is a ripple in the phase versus frequency characteristic of the actual device, it may differ significantly from the phase delay for an ideal non-dispersive delay device. Mathematically it can be represented as,
(1)
In order to measure the Group delay of the antipodal Vivaldi antenna the Big Vivaldi (Vivaldi 004) antenna is used as a benchmark antenna. The antennas are mounted face to face at a distance of roughly 60 centimetres, connected to the two VNA ports. Between the antennae, absorbing material is being inserted to prevent any ground reflections. Through VNA, the phase of the S21 broadcast signal as it travels from one antenna to the next is monitored. The Vivaldi 004 antennas undergo the exact same process again with the identical arrangement.
The derivative of the measured phase response with respect to frequency is then used to compute the group delay.
The Chase group anechoic chamber at Chalmers was used to quantify the gain. Prior to measuring the SGH's gain for the desired frequencies, the source (transmitter) and receiver SGH antenna were first aligned. The SGH antenna was then replaced by the AUT (antipodal Vivaldi antenna), while still maintaining the same distance between the source (transmitter) and receiver AUT. The same frequencies as before were used to measure the AUT's gain. The SGH is calibrated using calibrated data provided by the manufacturers, Scientific-Atlanta, INC. The following equation is used to calculate the AUT's final gain,

(2)

Where,
= Gain of SGH used for calibration
= Measurement of AUT gain in chamber
=Measurement of SGH gain of in chamber

Brief description of Drawing
Figure 1 Top view ofAVA antenna
Figure 2 Results of Reflection coefficient

Detailed description of the drawing
Figure 1 shows view of AVA modeled in HFSS. It has been obtained after designing an antenna with the referred parameters and input frequency.
Figure 2 shows the simulation analysis of Reflection coefficient an UWB antenna for a given input frequency.
4 Claims & 2 Figures , Claims:The scope of the invention is defined by the following claims:

Claims:
1. Every UWB radar application requires an antenna. In order to use the Novelda AS R2A radar chips, a planar, broadband, and directional Vivaldi antenna has already been created. The Vivaldi antenna has two working prototypes.

a) Systems offer improved range, precision and reliability in RADAR sensing and communication tasks.
b) Integration of RADAR communication systems, which includes industrial automation, surveillance and wireless sensing.
c) Vivaldi antenna is fabricated using cost-effective and scalable manufacturing techniques.
2. As mentioned in claim 1,the prototypes Vivaldi (150 mm x 132 mm) and another Vivaldi (60 mm x 46 mm) each operate in a different frequency range.
3. As per claim 1, the parallel strip line in the bottom layer is gradually widened to create the ground plane needed for the microstrip feeder, while the parallel strip line in the top layer is connected to the microstrip line by a tapered transmission line.
4. As mentioned in claim 1, comparing the AVA with other various methodologies like ABC, DE,PSO and ABC-DE etc, this model provide good reflection co-efficient and gain of the antenna.