Force 12 6 meter Yagi Information, 12/14/06

Force 12 6 meter Yagis are plug-and-play assembly. The elements are pre-cut and pre-drilled, plus the element brackets are already installed on the boom and engraved for proper element placement. The elements are .75" at the center and taper down to .375" at the tips. All booms are at least 2" in diameter.

All Force 12 6 meter Yagis are 50 ohm, direct feed design. This 50 ohm feed design also results in a wide operating bandwidth and was developed by Tom Schiller, N6BT back in the late 1980’s using HF antennas scaled to microwave models at 2.4 GHz. The first production amateur antenna was in 1993 and is the Force 12 Magnum 620 (6 elements, 44’ boom, 20 meters). As an example of its effectiveness, the forward gain on the Magnum 620 varies less than 0.1dB across the band and the F/B varies less than 1dB.

The direct 50-ohm design has been used on both amateur and commercial Yagis up to a 49 element 5.8 GHz unit. Besides the wide operating bandwidth, another advantage of the design is the simple feed system - no extra parts. Each 50-ohm design is manually done (no automatic optimizers). On Yagis with 6 or more elements, the gain and F/B are peaked at the center of the band. On the 3 and 4 element Yagis, the F/B is centered in the band, with the gain curve climbing slightly across the band.

The performance of these Yagis is unsurpassed. Many stations have compared them with other designs and have concluded Force 12 models to be superior. They have a cleaner, well-defined pattern and are also quieter on receive. They can be mounted either horizontally or vertically polarized. For vertical polarization, it is necessary to be sure the mast does not come into play. If running a pair vertically polarized side-by-side, the mast will not be involved.

Force 12 provides a wide variety of Yagis for 6 meters. For basic stations and portable use, the 3 and 4 element models are ideal. More DX-oriented stations select the 6 and 7 element models. Those who want to do EME can use a pair of the 9 element Yagis and those who want the top of the line, the Magnum 1406 is it. Stacking distances are available from Force 12.

Antenna Model	Boom Length	# ele	Windload	Frequency Coverage	Gain @45' dBi	Net Gain dBd	F/B in dB	1.5:1 VSWR Bandwidth	Turn Radius	Wt	Mast Torque in/lbs
EF-306	7.5'	3	1.4sqft	49.5 - 52.0	13.5	5.6	20	>1.5 MHz	8'	7#	<50
EF-406	8'	4	1.7	49.5 - 52.0	14.3	6.4	21	>1.5 MHz	8'	12#	<50
EF-606	12'	6	2.0	49.5 - 52.0	15.7	7.8	23	>1.5 MHz	8.3'	15#	<50
EF-706	18'	7	2.2	49.5 - 52.0	16.8	9.8	24	>1.5 MHz	10.3'	20#	<150
EF-906	30'	9	3.4	49.5 - 52.0	18.5	10.6	25	>1.5 MHz	15.8'	42#	<310
Magnum 1406	52'	14	7.5	49.5 - 52.0	20.3	12.4	25	>1.5 MHz	26.5'	83#	<750
Gain @45' dBi is the gain you would see when using a computer model. It is compared to the isotropic radiator and includes ground reflection gain.
Net Gain dBd is the gain as compared to a full size dipole in exactly the same location (i.e. height). It is, therefore, noted as "dBd", the last "d" meaning the full size dipole.

The 6 meter band is becoming more popular every year, especially with meteor scatter and EME. For EME, stacking Force 12 6 meter Yagis is the way to go for those high gain arrays.

The following are typical plots for Force 12's EF-706 Yagis. In all cases, the bottom Yagi is at 20' above typical ground. This means for the side-by-side horizontal stack, both are at 20'. For the 4x stacks, the lower antennas are at 20' and the upper ones are at 20' + the vertical stack height.

Antenna Array		horizontal	vertical	click on image for larger photo
1x1 array	2 Yagis spaced horizontally (boom center to boom center)	18'
1x1 array	2 Yagis spaced horizontally (boom center to boom center)	20'
		horizontal	vertical
2x2 array	4 Yagis spaced	16'	16'
2x2 array	4 Yagis spaced	16'	18'
2x2 array	4 Yagis spaced	18'	18'
2x2 array	4 Yagis spaced	18'	20'
2x2 array	4 Yagis spaced	20'	20'

As the horizontal space is increased, the gain increases, but the grating lobes (front-facing side lobes) also increase in intensity (are down less from the main lobe). This is important when doing EME, as the grating lobes can pick up noise.

Give us a call at 1 800 Number Is Coming Soon or send an e-mail to force12@sbcglobal.net for more information.