## 2 Literature Survey  
A rectangular waveguide (RWG)-to-microstrip line (MSL) transition is a two-port hybrid connector. It can transfer electromagnetic (EM) energy from a microstrip port to a waveguide port with minimum attenuation and low transmission losses. For wireless applications, RADAR applications, and millimeter wave applications, the designed transition requires a wide bandwidth across the determined center frequency. To meet these requirements, an enormous amount of research has been carried out and will be continued [1]. [PERSON] et al. proposed a narrow wall side inserted Ka-band semicircular ring magnetic coupling based RWG-to-MSL transition. It is compact and easy to manufacture. It also possesses a wide bandwidth for the full Ka-band. Nevertheless, it has poor insertion loss lies between \(-1\) dB and \(-2\) dB [3]. [PERSON] et al. designed a Ka-band 90\({}^{\circ}\) E-plane transition consisting of a multi-section step impedance transformer with minimum reflection and transmission losses over a fractional bandwidth (FBW) of 40% [4]. [PERSON] et al. presented an E-probe Ka-band Ms line-to-RWG transverse transition. This transition uses a single-step impedance transformer with an IL of \(-0.30\) dB over 14.54% FBW [5]. [PERSON] et al. proposed an E-plane transverse transition using a two-step impedance transformer and a rectangular probe, with low reflections below a \(-10\) dB bandwidth of 38% [6]. In this Ka-band E-plane side inserted RWG-to-MSL transition, impedance and field matching is possible by employing a multi-section microstrip line transformer [1,3, 4, 5, 6]. This results in good insertion loss (IL), S\({}_{12}\) and return loss (RL), and S\({}_{11}\) with a bandwidth below \(-10\) dB; in addition, it has a high degree of integration with MIC and MMIC circuits and devices. [PERSON] et al. presented an E-plane 90\({}^{\circ}\) inline MSL-to-RWG transition. Their design comprises a radial-shaped probe with a notch cut in the main microstrip, and an extended ground to match the field and impedance of the dominant waveguide mode. This transition exhibits a wide bandwidth, with satisfactory insertion and returns loss for the entire Ka-band [7,8]. [PERSON] et al. demonstrated and fabricated an E-plane 90\({}^{\circ}\) inline transition using a semicircular loop with a broadband bandwidth lower than \(-20\) dB return loss for the full Ka-band, using a single-step impedance transformer. The design also utilizes a thin-film resistor as a termination load [9]. [PERSON] et al. demonstrated an inline, low-cost, single-sided PCB, and impedance-transformer-less MS-to-WG transition with an IL of \(-0.40\) dB for a wide fractional bandwidth of 71.43% [10]. [PERSON] and [PERSON] proposed a transverse waveguide to coaxial transition, and field matching and impedance matching were achieved with a ridged waveguide, customized coaxial probe, and back-short distance. This transition had an IL of \(-0.47\) dB [11]. [PERSON] et al. investigated an inline Q-band transition, using a section of a ridged waveguide and Chebyshev impedance transformer, with an IL of \(-0.26\) dB over an FBW of 40% for the entire Q-band [12]. These conductive traces printed on flexible substrates offer many potential applications in the area of wearable electronics, ranging from search and rescue operations, to health and physiological monitoring. [PERSON] et al. investigated the effect of the pasting property on the dc conductivity of printed interconnects on a substrate, as well as the consequent RF performance up to the frequency of 30 GHz [13]. It is concluded from the background literature on MS line-to-WG transitions that, in most of the transitions, the microstrip line must contain a multiple section/single step Chebyshev impedance transformer or ridge waveguide structures.