(a) Bonds issued under this subchapter may be additionally secured by:
(1) an encumbrance on any real property owned by the municipality;
(2) an encumbrance on any personal property appurtenant to that real property; or
(3) a pledge of any portion of a grant, donation, revenue, or income received or to be received from the United States or any other public or private source.
(b) The governing body of the municipality may authorize the execution of a trust indenture, mortgage, deed of trust, or other instrument as evidence of the encumbrance.