The MFJ 1836 and MFJ 1836H G3TPW CobWebb Antennas
for the 14, 18, 21, 24, 28 und 50 MHz Bands cover all 6 Bands with low SWR. The SWR at the band edges is mainly reactive, i.e. the resistive component is still near 50 ohms, so auto and simple ATUs can match it with low loss. Over 95% radiation efficiency on all bands! Radiation pattern is nearly omni-directional so you don’t need a rotator.
The six “squares” are made from white PVC covered multi stranded copper twin cable which is supported by a horizontal cross, made from grey fibre glass. Each element is folded and tapped for impedance matching, so that the antenna looks like 50 ohms on all 6 bands. The small size ensures minimum windage and the low weight means that TV type brackets and masts may be used for supports. This sixband half-wave open-loop is perfect for restricted space or portable operation.
It is a very efficient horizontally polarised omni-directional antenna for the 14, 18, 21, 24, 28 and 50 MHz bands, with a gain of 7 dB over an isotropic radiator (7dBi). Note that this is the same as a standard dipole, although a straight dipole will have sharp nulls off each end. Up to 5 dBi gain will allow you to work DX easily -- even on QRP.
Nearly all the power fed into the CobWebb will be radiated, so the antenna will not heat up and so limit the power rating. There are no ferrites used so no intermods are produced. CobWebb antennas are not affected by the nearby environment so THEY WORK AT ALL LOCATIONS.
The antenna is supplied with a prefab matching network consisting of current balun with coax pigtail with a shear flow filter and SO 239 (PL female) connection. The MFJ 1836 is loadable with max. 300 W PEP (SSB); the MFJ 1836H with max. 1500 W PEP (SSB).
|Minimum SWR|| : ||1.2 :1 or less on all bands, measured at 6 m AGL|
|Gain|| : ||4,7 dBi at 6 m AGL on 14.2 MHZ with a 37º TOA|
|Dimensions|| : ||2,75 x 2,90 m; diagonal approx. 4,00 m|
|Balun|| : ||1:4 incl. Ferrite-sleeve choke over coax pigtail w. SO 239|
|Connector|| : ||SO 239 (PL female)|
|Power|| : ||MFJ 1836 = 300 Watt PEP, SSB/CW, ICAS (<50% transmit time)|
| : ||MFJ 1836H = 1500 Watt PEP, SSB/CW, ICAS (<50% transmit time)|
|Mast diameter|| : || Max. ø 44 mm|
|Weight|| : ||4,4 kgs|
Dimensions and weight are including packaging
||L194 x B20 x H12 cm