problem on implementation of the ultrasonic circuitry I used an Arduino Uno on my project to produce a frequency greater than 35000Hz and the output of digital pin was connected to the ultrasonic transmitter circuitry:

 

However, it's not working on the transmitting side. Here's the Arduino code:

void setup()
{
    Serial.begin(9600);
}

void loop()
{
    pinMode(13,OUTPUT);
    pinMode(12,OUTPUT);
    int pirSenses = analogRead(A1);
    int pirOuts=11;
    pinMode(pirOuts,INPUT); /*PIR sensor 1*/
    int pirSense = analogRead(A0);
    int pirOut = 10;
    pinMode(pirOut,INPUT); /*PIR sensor 2*/
    Serial.println(pirSense);Serial.println(pirSenses);

    if (pirOut || pirOuts == HIGH)
    { /*tone produces ultrasonic frequency*/
        delay(8000);
        tone(13, 50132); delay(100); noTone(13); delay(10);
        tone(13,54621);  delay(50);  noTone(13); delay(50);
        tone(13,35689);  delay(60);  noTone(13);
    } 
    else if (pirOut||pirOuts==LOW)
    {
        tone(13, 50132); delay(100); noTone(13); delay(10);
        tone(13,54621);  delay(50);  noTone(13); delay(50);
        tone(13,35689);  delay(60);  noTone(13);
    } 
    else
    {}
}


And the transmitter (model "MCPCT-G5100-4139") specification:



Please help me with this problem. Thanks!
Your ultrasonic Transducer driver circuit isn't doing a very good job. At most you are getting only a few milliwatts output to the transducer. Your circuit is applying 12 volts through a 2.2K resistor to the transducer, and your Q1 transistor is merely shorting out the Transducer.  

From viewing the data sheet on your transducer, it looks like a tiny loud speaker and not a Piezo device. But that is OK.  

Try the following push pull driver circuit.  I have tried to keep it simple, but you would need to come up with a PNP transistor (in addition to your existing NPN transistor).  

The V2 square wave is your 5 volt output from Arduino.  

Also, notice that I have shown the driver circuit using 5 volts, not 12 volts. Using this circuit, if you use 12 volts supply, the output doesn't get any more powerful, and just causes more heating in the transistors.   

EDIT 1  :  IMPORTANT :  Don't leave your output pin in the HIGH state.  This turns on transistor Q1 and causes sustained current in the Transducer.  To alleviate this, insert a 47uf capacitor in series with the transducer.  

EDIT 2 :  Changed schematic to include output capacitor.