## 6 Validation in a Semi-Urban Bistatic Radar Scenario  
### Scenario Description  
The capabilities of the designed NULA and the two-step beamforming processing are evaluated in a real radar scenario, in the nearby area of the Polytechnic School of University of Alcala (Spain). The PRS is located at the rooftop terrace of the Polytechnic School. This scenario is characterized as a semiurban environment: low-height buildings belonging to the University Campus surrounded by countryside and several roads (Alcala-Meco road, R2 highway and inner-campus secondary roads). A controlled car with a GPS device was running along Alcala-Meco road within the area of interest.  
In the considered radar scenario, there is one DVB-T transmitter (Torrespana), with an Equivalent Radiated Power (ERP) equal to 20 kW, which is used as IoO taking into consideration its high radiated power and its omnidirectional radiation pattern. The estimated received power levels provided by this IoO in the surveillance area are depicted in Figure 15. Coordinates of the main elements of the geometry are presented in Table 8.  
In order to obtain the system coverage, the Bistatic Radar Cross-Section (BRCS) of the targets of interest was estimated in [8]. A Mazda 6 SPORT vehicle was considered as a representative target for traffic monitoring. A study of the scenario geometry revealed that the bistatic angles varied from 105\({}^{\circ}\)-135\({}^{\circ}\). In Table 9, BRCS representative values are summarized. For coverage studies, \(\sigma_{bistatic}=10.6118\) dBsm was used.  
In Figure 16, the single element antenna radiation pattern in the horizontal plane is superimposed on the scenario image to show the instrumented coverage sector. The antenna orientation was selected to ensure that the maximum of the radiation pattern was pointed towards the area of interest in order to enclose the roads under study.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Latitude** & **Longitude** & **Altitude** \\ \hline
**Torrespaña transmitter** & 45\({}^{\circ}\)25\({}^{\prime}\)16.64\({}^{\prime\prime}\)N & 3\({}^{\circ}\)39\({}^{\prime}\)51.39\({}^{\prime\prime}\)W & 658 m \\
**IDEPAR receiver** & 40\({}^{\circ}\)30\({}^{\prime}\)47.19\({}^{\prime\prime}\)N & 3\({}^{\circ}\)20\({}^{\prime}\)55.02\({}^{\prime\prime}\)W & 628 m \\ \hline \hline \end{tabular}
\end{table}
Table 8: IoO and IDEPAR receiver emplacement coordinates.  
Figure 15: Received power levels provided by the Torrespaña Illuminator of Opportunity (IoO) in the considered radar scenario.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Bistatic Angle** & **555\({}^{\circ}\)** & **70\({}^{\circ}\)** & **90\({}^{\circ}\)** & **105\({}^{\circ}\)** \\ \hline
**BRCS** & 10.6118 dBsm & 13.7543 dBsm & 12.9469 dBsm & 12.9589 dBsm \\ \hline \hline \end{tabular}
\end{table}
Table 9: Representative average values of the estimated BRCS of the car model selected for the study. BRCS, Bistatic Radar Cross-Section.  
In the experiment, a set of 20-s length acquisitions was recorded. For each data acquisition, 80 range-Doppler matrices were generated using the following processing parameters:  
* 58 th DVB-T channel: \(f_{p}=770\) MHz, \(B=8\) MHz.
* \(T_{int}=250\) ms.
* CAF size: 401 Doppler shifts, \(f_{d}\in[-799.744\) Hz; 799.744 Hz]; 1000 range bins (9.45 km along the array broadside).
* Broadside direction: 356.51\({}^{\circ}\)N.
* Surveillance antenna: 5 elements NULA array with inter-element distances equal to those calculated in Section 3.2; single radiating element: TELEVES 4G NOVA. Better results could be obtained with an NULA with 11 elements, but the current demonstrator used to validate the results only has six receiving channels, which limits the number of elements in the array to five, if one channel is used to acquire the reference signal.