Description

Deployable by one person in less than 10 minutes, the Base Military HF ‘Skywave’ Antenna for 1.5-30MHz (Model B1.5-30) is a complete wide-band base antenna with low noise receive, which is perfect for broadband spread spectrum coverage that is encrypted or not.

Characteristics

Low noise receive characteristics occur due to the entire antenna system being placed close to the earth. This balanced system requires no additional components be added to maintain a maximum SWR of 3:1 during transmission.

Analysis		Layout Measurements Axial radius = 30 x 30 feet Footprint = 60 feet x 60 feet Height = 34 feet   Specifics Z0 – Z1 = 18 feet Z0 – Z2 = 6 feet Z1 – Z2 = 24 feet   Z0 – X1 = 35 feet Z0 – X2 = 35 feet Z0 – Y1 = 35 feet Z0 – Y2 = 35 Feet   Z2 – X0 = 30 feet Z2 – Y0 = 30 feet
Elevation/Azimuth Pattern	Simulated Pattern

Pattern The Z1 – Z0 Vertical element provides Groundwave coverage while it simultaneously maintains a null above the antenna. This enables the Z0, X1 & 2, and Y1 & 2 NVIS elements to enhance consistent NVIS and Sky-wave patterns, which is universally represented in the above ‘Elevation/Azimuth Pattern’ & ‘Simulated Pattern’. The Z0 – Z2 Grounded Counterpoise then completes the circuit, by providing a path to ground at the feed-point Z0.Gain Some gain (directivity) is realized by the placement of the Z1 – Z0 Vertical element above the Z0, X1 & 2, and Y1 & 2 NVIS elements. For the most part, however, this antenna is onmi-directional, which results in negative gain when compared to a dipole. Fortunately, gain does not only come from antenna design. There is also “ground gain”, which can add an approximately 6 dB of additional gain to the following gain figures also represented graphically here. Frequency (MHz) Gain (dBi) 2 -27 + 6 = -21 7.5 -15 + 6 = -9 15 -9.4 + 6 = -3.4 22.5 -8.2 + 6 = -2.2 30 -6.5 + 6 = -.5