*DX RESOURCES* Castles on the Air (COTA)

A Definition

COTA is an acronym for the special radio DX activity on ham bands and 11m known as ‘Castles On The Air’.

For the purpose of COTA, a castle is…

“a type of fortified structure of residence or a lord or noble, built during the Middle Ages by military orders…”

Alternatively, a fortification, fort or fortress is…

“a military construction or building designed for the defense of territories in warfare, also used to solidify rule in a region during peacetime. The term is derived from the Latin fortis and facere…”

COTA is an exciting concept most likely born in Spain (home to many of the world’s finest castles) which involves radio transmissions occurring from castle grounds or within a maximum of 500 metres from castle walls.

A slight variation of that phrase, yet one which carries the same implication and is commonly added as a suffix to the callsigns of Freeband operators undertaking COTA activity, is the term CF (Castles and Fortresses).

While CF stands for Castles and Fortresses, the first two letters or numbers after CF refer to the department, province, state, county or other where the CF is located.

The suffix, composed of three numbers, is the reference assigned to the castle or fortress.

Who Invented COTA?

The Delta Radio DX Group is credited by most as the creator of the COTA concept.

In the early 2000s, the DR ‘World Castles and Fortresses Weekend’ was one of the most eagerly anticipated weekends of DX adventure in many sections of the Freeband Community with activities occurring in most continents of the world.

The Purpose of COTA

Like ‘Lighthouse On The Air (LOTA)’ activations, COTA activity presents an opportunity for radio operators to educate and promote the historical significance and architectural uniqueness of castles and forts.

In the past, they have also been used in conjunction with important fundraising ventures to assist with the repair or renovation of ‘at risk’ castles.

COTA in the DA-RC

Our Dx Adventure Radio Club fully supports the COTA concept, including its objectives as outlined by the now defunct Delta Radio (DR) group.

DA-RC members, in fact, have undertaken many castles and fortresses activities in the past in the Middle East, Europe and Pacific areas and will continue to do so in the future.

Recognizing COTA Efforts

The DA-RC Achievement Program offers a fabulous range of awards which include a COTA Hunter Award for the operator who successfully works and confirms 50 COTA stations, as well as four COTA DXpeditioner Awards for 10, 20 and 30 activities respectively.


To activate a COTA or CF entity, or for more info on structures close to your QTH, including references, history, grid squares, coordinates and more, please contact DA-RC HQ for support!