ℹ️ --- The Patriot system has four major operational functions: communications, command and control, radar surveillance, and missile guidance. The four functions combine to provide a coordinated, secure, integrated, mobile air defense system. The Patriot system is modular and highly mobile. A battery-sized element can be installed in less than an hour. All components, consisting of the fire control section (radar set, engagement control station, antenna mast group, electric power plant) and launchers, are a truck- or trailer-mounted. The radar set and launchers (with missiles) are mounted on M860 semi-trailers, which are towed by Oshkosh M983 HEMTTs. Missile reloading is accomplished using a M985 HEMTT truck with a Hiab crane on the back. This crane is larger than the standard Grove cranes found on regular M977 HEMTT and M985 HEMTT cargo body trucks. The truck/crane, called a Guided Missile Transporter (GMT), removes spent missile canisters from the launcher and then replaces them with fresh missiles. Because the crane nearly doubles the height of the HEMTT when not stowed, crews informally refer to it as the "scorpion tail." A standard M977 HEMTT with a regular-sized crane is sometimes referred to as the Large Repair Parts Transporter (LRPT). The heart of the Patriot battery is the fire control section, consisting of the AN/MPQ-53 or −65 Radar Set, the AN/MSQ-104 Engagement Control Station (ECS), the OE-349 Antenna Mast Group (AMG), and the EPP-III Electric Power Plant. The system's missiles are transported on and launched from the M901 Launching Station, which can carry up to four PAC-2 missiles or up to sixteen PAC-3 missiles. A Patriot battalion is also equipped with the Information Coordination Central (ICC), a command station designed to coordinate the launches of a battalion and uplink Patriot to the JTIDS or MIDS network.
There were many more upgrades to PAC-2 systems throughout the 1990s and into the 21st century, again mostly centering on software. However, the PAC-2 missiles were modified significantly—four separate variants became known collectively as guidance enhanced missiles (GEM).
The main upgrade to the original GEM missile was a new, faster proximity fused warhead. Tests had indicated that the fuse on the original PAC-2 missiles were detonating their warheads too late when engaging ballistic missiles with an extremely steep ingress, and as such it was necessary to shorten this fuse delay. The GEM missile was also given a new "low noise" seeker head designed to reduce interference in front of the missile's radar seeker, and a higher performance seeker designed to better detect low radar cross-section targets.
📑 ➖➖➖ South Korea’s Defense Acquisition Program Administration (DAPA) announced on 12 December that deliveries of Patriot Advanced Capability-3 (PAC-3) interceptor missiles and upgraded ground equipment to the Republic of Korea Air Force (RoKAF) has been completed amid Seoul’s efforts to enhance the country’s air defences to counter North Korea’s growing ballistic missile capabilities.
The agency said deliveries of the upgraded air-defence systems were completed in November – 10 months ahead of schedule – under a Patriot capability enhancement programme launched in March 2015 and carried out in close co-operation with the United States and South Korean companies.
DAPA said the detection range of the PAC-3’s radar system is twice that of the RoKAF’s previously deployed PAC-2 system, adding that the PAC-3 can also track and engage more targets simultaneously.

▪️ 🛠Designer Raytheon, Hughes, and RCA
▪️✅ Designed 1969
▪️💱 Unit cost About US$2–3 million
▪️⬇️ Mass 700 kg (1,500 lb)
▪️📏 Length 5,800 mm (19 ft 0 in)
▪️↔️ Diameter 410 mm (16 in)
▪️💥 Warhead M248 Composition B HE blast/fragmentation with two layers of pre-formed fragments and Octol 75/25 HE blast/fragmentation
▪️⬇️ Warhead weight 200 lb (90 kg)
▪️💥Detonation mechanism Proximity fuse
▪️↔️ Wingspan 920 mm (3 ft 0 in)
▪️🛢 Propellant Solid-fuel rocket
▪️📡 Operational range PAC-1: 43 mi (70 km)
PAC-2: 60–99 mi (96–160 km)
PAC-3: 12 mi (20 km) against ballistic missile
PAC-3 MSE: 22 mi (35 km)
▪️↗️ Flight altitude 79,500 feet (24,200 m)
▪️⏩ Maximum speed PAC-1: Mach 2.8
PAC-2/PAC-3: Mach 4.1
▪️⬆️ Launch platform Mobile trainable four-round semi-trailer

Ref: Wikipedia; Janes.