She was accompanied by HRH Princess Chulabhorn Valayalaksana. Army chief General Anupong Paochinda also attended the funeral.
Supporters of the People's Alliance for Democracy also showed up to pay their respects to Angkana.
Angkana's father, Jinda, told reporters HM the Queen had extended moral support to his family for the loss of his daughter.
"HM the Queen told me that Angkana was a good girl, that she had helped protect the country and the monarchy," Jinda told reporters after the cremation.
The Queen also said His Majesty the King had been informed of the matter and that donations to the Radubpanyawoot family was HM the King's contribution, Jinda said.
Angkana's sister, Daranee, said the Queen told her to take good care of her parents and inquired about the health of her mother, who was in hospital.
"I told Her Majesty that my mother lost two of her toes in an explosion," she said. "Her Majesty extended her blessings for my mother to recover quickly."
Daranee said she could never have imagined HM the Queen would attend her sister's funeral.
"I was so grateful that I had tears in my eyes. Some of my sister's ashes will be sprinkled on the river near Wat Chonglom, and the rest will be kept at Wat Tuk.
Meanwhile, Prime Minister Somchai Wongsawat yesterday evening requested an audience with HM the King in Hua Hin. Somchai said he had reported on the present situation to His Majesty.
"I am currently not discouraged to continue my work. I will continue my duty as long as I am still in the post." However, he appeared stressed during his short interaction with the media.