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40-Meter, 2-element wire beam, Chrisman phased, easily modified for any band. Total cost: $50

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N4JTE-@ 7160.0 UR5VFS tnx Serge 0324 18 Aug Ukraine N4JTE-@ 7157.0 6Y5JH tnx 5-9 ny, Henry 0238 17 Aug Jamaica N4JTE-@ 7155.0 CG100NS Sp event nova scotia, tnx jim 2209 16 Aug Canada N4JTE-@ 7145.0 HB9JW Tnx for great qso Fred. 0350 16 Aug Switzerland N4JTE-@ 7155.0 OM5DP tnx Martin 5-9 NY 0329 16 Aug Slovakia N4JTE-@ 7160.0 LZ1JY Nick always loud my friend 0338 15 Aug Bulgaria N4JTE-@ 7162.0 OJ0UR got him too woohoo 0245 15 Aug Market Reef N4JTE-@ 7135.0 IT9AUG Tnx carmello and Lucio 2156 14 Aug Sicily N4JTE-@ 7135.0 IT9AUG Tnx carmello and Lucio 2152 14 Aug Sicily N4JTE-@ 7147.5 G0NCE Tnz Owen, 5-7 NY 2143 14 Aug England F5VLY 7147.5 N4JTE Thanks Bob 73sss 2143 14 Aug United States N4JTE-@ 7142.0 OM5MZ tnx boby 0320 13 Aug Slovakia N4JTE-@ 7148.0 DF2BO voice of germany, tnx tom 0315 13 Aug Germany N4JTE-@ 7145.0 ON4DY Tnx bob 5-9 as usual. 0414 12 Aug Belgium N4JTE-@ 7153.0 SP3GXH 5-9 Chris, tnx 0359 12 Aug Poland N4JTE-@ 7128.0 4X4BL tnx, 5-9 NY correct call now. 0347 12 Aug Israel N4JTE-@ 7160.0 DF2DJ Tnx john 5-9 NY 0301 11 Aug Germany N4JTE-@ 7160.0 9Y4LAS tnx andy 5-9 NY 0439 10 Aug Trinidad & T N4JTE-@ 7145.0 TY1KS confusing, sudan on same freq? 0419 10 Aug Benin N4JTE-@ 7147.0 GM4YSN tnx Ian, perfect 5-9 and audio 0451 08 Aug Scotland N4JTE-@ 7153.0 8R1Z tnx len, 5-9 in NY 0012 08 Aug Guyana N4JTE-@ 7138.0 RW3GW 5-6 in NY tnx lorry 0308 06 Aug European Russia N4JTE-@ 7135.0 4X4BL good to hear Israel, tnx 0328 30 Jul Israel N4JTE-@ 7135.0 4X4BL Tnx ZVE, great signal from Israel 0326 30 Jul Israel YO8RNI 7160.0 N4JTE 0226 29 Jul United States
If you have any interest in building a very inexpensive reversible monoband beam with excellent results then read on and I will attempt to describe the process in detail. Often antenna articles seem to rely on perception and most times a lack of actual on air evaluations and validation of the design. That is the only reason I put up a small sampling of my last 30 days of DX activity.
Stateside this design serves very well from NY to CA and most spots in between depending on time of day as verified by the usual 50 to 75 checkins on the OMISS net during my NCS duties with summertime static at 0100 on 7.185, using an old IC 751A with 400 watts. ASL here is 385 feet in my Hudson Valley location surrounded by mountains. Love to try this sucker in Florida!
On air: The model shows only 11db front to back but this antenna receives consistent 25 db + front to back reports and 5-9 plus reports from DX stations nightly, probably my lack of modeling skills with phaselines! I use a tuner to maximize matching but the actual swr is about 1.6 to one and slightly higher with East switched on when on 7.160. Got a big noisy 3 story building about 50 ft away! The usable bandwidth is from 7.125 to 7.200 based on gain and front to back reports from many stations. The design is competing incredibly well at 45 feet with the many large tower, 2 and 3 element monobanders I deal with a lot of nights.
The DX summit list was provided to illustrate my contacts with those stations and does not note that I was usually the first US station that evening to post and work the DX including the Market Reef, Benin and Sudan ssb on 40 meters.

1: Build two dipoles of equal length, I ended up with 63 feet of insulated #14 insulated wire from home depot at around 13 cents a foot. I resonated, lowest swr, for 7.185 the first one and made second the same exact length.
2: The two 84 degree feedline stubs and the 71 degree phase line are measured and cut by using any method available. My previous article "verticals got two" presented a very detailed method when using an analyzer.
Another method is to simply use a tee connector from the back of the transmitter. The feedline is connected to one connector and a 50 to 100 watt dummy load to the other.
A decent swr meter is placed in between the radio and center connector of the tee; see ON4UN DX lowbanding for illustration. You apply very low wattage out and look for the lowest swr at the frequency you need to see to verify you are at 84/71 degrees. I used RG59 radio shack coax due to ease of supply here in town. I have not had any problems with any power levels up to 1500 watts; of course keeping things close to resonance is mandatory.
FORMULA:
84/90 =7.185 (your frequency)/X
84x=646.65
x= 7.69M
71/90= 7.185/x
71x= 646.65
x= 9.107M
This formula is based on the properties of 90-degree open and shorted lines and the Christman method of forcefeeding equal currents and phase to both dipoles. When doing your measuring and cutting with this method make the opposite end of tested coax shorted. Cut and measure till you reach the lowest swr on the frequency of your design, in this case for 7.185 I needed to see 7.69 for the feedlines, and 9.107, for the phaseline.
I am not going to give the physical lengths that I ended up with because all coax is different, relying on velocity factors is a waste of time and effort. I have determined that using 1/4 WL spacing, 33 ft. gives the best bang for the buck with this design.
3: Relay; Man these things opened up so many possibilities for me when designing antennas. RADIO SHACK# DPDT 275-0218 costs about $8, used to be $6 till I bought them out! Hopefully the illustration is clear enough but simply put the first two connectors go to a 12-volt power supply in shack. Next two go to shack feedline -- I use RG 213. Next two go to front and last two at the normally on posts. The 71-degree line is connected across front and rear antennas. The most important part is to maintain polarity on all connections, + voltage and center wire of coax's all on same side. Waterproof, I put everything into a radio shack box, $3, your mileage may vary...
As one of my big gun DX friends said one night after I was given a 28 db front to back equal to his two-element $5000 tower/monobander at 80-feet. Even a blind squirrel finds a nut once in awhile, and it did not take 30 seconds to turn anything here!
The Layout: The dipoles, at the center feedpoints are supported by string thru available trees and spaced 1/4 WL apart about 45 ft high or so. The ends were tied off as flat as possible to available supports, they are not truly flatopped but close. The 84-degree lines are each fed to the dipoles with a typical dipole feed technique and will come down in a vee configuration to the relay at the point of shack feedline and 12 volt supply connection. The 71-degree phase loop hangs down from box. I made a special effort to make sure the center point spacing was maintained by using a masonry 33ft string and pulling everything nice and tight up in the air.
At that height the relay and feed stubs are easily reached with a 8 ft stepladder for checking things when a little slack is provided from center support strings. In the shack I use a lightswitch screwed to the desk with groundside of 12 volt 3 amp RS supply as the on/ off direction changing device.
FINAL THOUGHTS: Hopefully I have provided enough info to make someone interested in trying out this design. I believe that this design is the first use of the Christman system in a two element flattop dipole configuration and it was a big guess by using phased vertical design parameters. A little space is needed but remember, you can shrink the dipole lengths by 30% by letting dipole ends hang down from nonconductive supports with no appreciable loss of gain. An inverted vee at 33 to 40 feet high should work as well if elements are carefully resonated. However the 1/4 WL spacing is critical for this design.
I plan on building another for 80 meters in a Vee configuration and anticipate great results. I have sent off a couple of the 40-meter prototypes to friends on the air, hopefully their results will match mine in different locations and their observations will be available by the time this thing is published.
Tnx for reading,
Bob Raynor, N4JTE