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In its use as a television antenna, it was common to combine a log-periodic design for VHF with a Yagi for UHF, with both halves being roughly equal in size. This resulted in much higher gain for UHF, typically on the order of 10 to 14 dB on the Yagi side and 6.5 dB for the log-periodic. [5]
A directive antenna with moderate gain of about 8 dBi often used at UHF frequencies. Consists of a dipole mounted in front of two reflective metal screens joined at an angle, usually 90°. Used as a rooftop UHF television antenna and for point-to-point data links. Parabolic The most widely used high gain antenna at microwave frequencies and above.
VHF radio is also used for marine Radio [8] as per its long-distance reachability comparing UHF frequencies. Example allocation of VHF–UHF frequencies: [9] Radionavigation 60: 84–86 MHz; Fixed Maritime Mobile: 130–135.7 MHz; Fixed Aeronautical radio navigation: 160–190 MHz; Broadcasting Aeronautical Radionavigation: 255–283.5 MHz
An antenna array (or array antenna) is a set of multiple connected antennas which work together as a single antenna, to transmit or receive radio waves. [ 1 ] : p.149 [ 2 ] The individual antennas (called elements ) are usually connected to a single receiver or transmitter by feedlines that feed the power to the elements in a specific phase ...
A high-gain antenna (HGA) is a directional antenna with a focused, narrow beam width, permitting more precise targeting of the radio signals. [1] Most commonly referred to during space missions , [ 2 ] these antennas are also in use all over Earth , most successfully in flat, open areas where there are no mountains to disrupt radiowaves.
Also called a beam antenna [4] and parasitic array, the Yagi is widely used as a directional antenna on the HF, VHF and UHF bands. [3] [4] It has moderate to high gain of up to 20 dBi, [3] depending on the number of elements used, and a front-to-back ratio of up to 20 dB.
The two-element design gives modest directivity (about 2.0 dB) with a null towards the rear of the antenna, yielding a high front-to-back ratio: Gain up to 9.7 dBi can be achieved at 28 MHz. [3] Because the placement and size of the parasitic reflector both depend highly on wavelength, each Moxon antenna functions properly on the frequency band ...
The X-shaped dipoles give it a wide bandwidth to cover both the VHF (174–216 MHz) and UHF (470–700 MHz) bands. It has a gain of 5 dB VHF and 12 dB UHF and an 18 dB front-to-back ratio. The example shown is horizontally polarised. Reflective array 'billboard' antenna of the SCR-270 radar, an early US Army radar system. It consists of 32 ...