popup menu resize height and width

Question

I wanna increase the width of my popup menu, when i click on menu button it open in the corner and small in size, I want to increase its size from small to the both ends.

here is my code of popup menu,

        ivmainmenu.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

            PopupMenu popup = new PopupMenu(Home.this,ivmainmenu);
            popup.getMenuInflater().inflate(R.menu.popupmenu,popup.getMenu());

            popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {

                @Override
                public boolean onMenuItemClick(MenuItem item) {
                    // TODO Auto-generated method stub

                    switch (item.getItemId()) {
                    case R.id.ourwork:

                        Intent intent = new Intent(Home.this,Ourwork.class);
                        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                        startActivity(intent);

                        break;

                    case R.id.aboutus:

                        Intent intent2= new Intent(Home.this,Aboutus.class);
                        startActivity(intent2);

                        break;

                    case R.id.services:

                        Intent intent3= new Intent(Home.this,Services.class);
                        startActivity(intent3);
                        break;
                    case R.id.contact:

                        Intent intent4= new Intent(Home.this,Contact.class);
                        startActivity(intent4);
                        break;
                    }

                    return true;
                }
            });

            popup.show();
        }
    });

this is my way it looks,

I want it in the full widht and below the alfadesign logo, can it possible?

please help me regarding these, thank you.