How fetch radiobutton?

I have 3 radio buttons with their respective values I want to fetch so that the query used sees which value was selected and after the submit button is clicked it executes that command

below you will see an example of what I want to do

my index.php

 <form id="myForm">
        <label>
            <input type="radio" class=" radio"   name="rdoName" value="today"/>
            <span>today</span>
        </label>
        <label>
            <input type="radio" class="radio"name="rdoName" value="week"/>
            <span>week</span>
        </label>
        <label>
            <input type="radio" class="radio" name="rdoName" value="month" name="radio"/>
            <span>MONTH</span>
        </label>
    </form>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">exit</button>
        <button type="button"id="btnSubmit"value="Export"  class="btn btn-primary" /button>
       




<script>
    $("#btnSubmit").click(function(){
                     {
        $("#myForm").on('change',function()
                         {
           
            var value=$("input:radio[name=rdoName]:checked").val();
            $.ajax(
            {
                url:'export.php',
                type:'POST',
                data:'request='+value,
               
                
            });
        });
    });
    
</script>

now export.php

<?php
header('Content-Type: text/html; charset=utf-8');
// (A) CONNECT TO DATABASE - CHANGE SETTINGS TO YOUR OWN!
$dbhost = "localhost";
$dbname = "contador";
$dbchar = "utf8";
$dbuser = "root";
$dbpass = "";
$pdo = new PDO(
  "mysql:host=$dbhost;charset=$dbchar;dbname=$dbname",
  $dbuser, $dbpass, [
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_NAMED
  ]
);

// (B) LOAD PHPSPREADSHEET
require "vendor/autoload.php";
use PhpOffice\PhpSpreadsheet\Spreadsheet;
use PhpOffice\PhpSpreadsheet\Writer\Xlsx;

// (C) CREATE A NEW SPREADSHEET + WORKSHEET
$spreadsheet = new Spreadsheet();
$sheet = $spreadsheet->getActiveSheet();
$sheet->setTitle("folow");

// (D) FETCH USERS + WRITE TO SPREADSHEET
$stmt = $pdo->prepare("SELECT * FROM `contador`");
$stmt->execute();
$i = 1;

CREATE A NEW SPREADSHEET

$spreadsheet = new Spreadsheet();
$sheet = $spreadsheet->getActiveSheet();
$request=$_POST['request'];

exit for the 1

if($request=="today"){
while ($row = $stmt->fetch()) {
    $data= $row['Data'];
    $row['Data']= new DateTime(  $data );
    $sheet->setCellValue("A".$i, $row["ID"]);
    $sheet->setCellValue("B".$i, $row["Name"]);
    $sheet->setCellValue("C".$i, $row["Date"]-> format( 'd/m/Y' ));
    $i++;
  }
}

exit for the 2

if($request=="week"){
while ($row = $stmt->fetch()) {
    $data= $row['Data'];
    $row['Data']= new DateTime(  $data );
    $sheet->setCellValue("A".$i, $row["ID"]);
    $sheet->setCellValue("B".$i, $row["Name"]);
    $sheet->setCellValue("C".$i, $row["Date"]-> format( 'd/m/Y' ));
    $i++;
  }
}

exit for the 3

if($request=="month"){
while ($row = $stmt->fetch()) {
    $data= $row['Data'];
    $row['Data']= new DateTime(  $data );
    $sheet->setCellValue("A".$i, $row["ID"]);
    $sheet->setCellValue("B".$i, $row["Name"]);
    $sheet->setCellValue("C".$i, $row["Date"]-> format( 'd/m/Y' ));
    $i++;
  }
}
    

SEND DOWNLOAD HEADERS

// ob_clean();
// ob_start();
$writer = new Xlsx($spreadsheet);
header("Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet");
header("Content-Disposition: attachment;filename=\"demo.xlsx\"");
header("Cache-Control: max-age=0");
header("Expires: Fri, 11 Nov 2011 11:11:11 GMT");
header("Last-Modified: ". gmdate("D, d M Y H:i:s") ." GMT");
header("Cache-Control: cache, must-revalidate");
header("Pragma: public");
$writer->save("php://output");
// ob_end_flush();