Do you’ve gotten bother getting your cell sign into the LEO satellites? Do this small 2 meter vertical antenna together with your cell rig or HT and revel in extra success in your uplink. I constructed this small vertical as a result of I couldn’t uplink very effectively at low elevations and I simply couldn’t carry myself to drill holes within the roof of my new truck to put in a extra substantial antenna. I had been utilizing a quite common 1/4 wl mag-mount with solely marginal outcomes.Design:It is a high-efficiency “acquire” antenna. It’s not mounted completely: I’ve a magnet connected to it and “throw” it up on the roof once I wish to work a LEO ggstore.web antenna is an atypical vertical: as a substitute of the frequent 1/4 wl vertical monopole or 14/ wl floor aircraft with 1/4 wl radials, this design employs a 3/8 wl vertical part and brief radials to finish the “floor aircraft.” Successfully, an off-center-fed vertical dipole that doesn’t depend on the earth or, in my case the truck physique, to finish the underside half of the ggstore.web is a vital level. The very fact the antenna has a completely contained decrease half, i.e., the bottom aircraft, makes it very environment friendly. That is particularly vital when in comparison with my mag-mount monopole antenna the place the “floor aircraft” needed to be accomplished by way of the coax, by way of the rig, then to the car physique. I believe the mag-mount was not very environment friendly in any respect. The dipole is off-center-fed to get a greater match to the feedline and the underside “half” of the antenna is accomplished with capacitive reactance from the 4 shortened ggstore.web design has an sincere 3 dBi of acquire at 6′ elevation (2 dBi free-space) with an acceptable sample for LEO communications-favoring the horizon. At 20′ excessive, the identical antenna reveals nearly 6 dBi of acquire. The feedpoint is a nominal 50 Ohms at 146.850 mHz.
Development:The antenna is constructed utilizing a 3/4″ PVC tee, a cap for the highest, and a plug (flat on the underside) for the underside. The tee is organized vertically with the highest cap drilled for connection of all 5 components (I used 6-32 chrome steel botls/nuts/washers) and the underside plug is drilled for connection of a magnet (optionally available).The coax is fed through the open aspect of the tee and linked on to the weather by way of ring lugs. Alternately, a lower-profile model could possibly be constructed substituting a coupling for the tee and drilling a gap in it for the coax to exit. I linked the middle of the coax to the mast and the defend to one of many radials utilizing crimp fashion ring terminals. I then wrapped some small gauge wire across the outdoors of the cap, connecting all 4 radials collectively, and lined the meeting with electrical tape and ggstore.web determine at proper exhibits the structure and dimensions (in cm) of the weather. A 25-3/16″ (64 cm) vertical part is mixed with 4 7-3/16″ (20 cm) radials. I like to recommend you make the weather barely longer after which trim them based mostly on SWR readings. I used 10 gauge insulated wire for all the weather, however 1/8″ or 3/16″ aluminum rod could be an acceptable material-and probably extra sturdy. When tuning for minimal SWR, I finally pruned the mast to 24-3/4″ and the radials to 7″ to get a 1.2:1 SWR. That’s a lot better than my mag-mount ever confirmed so I finished fine-tuning and put it on the ggstore.web radials are angled down at about 30 levels. This angle might be adjusted to get the SWR excellent as soon as the vertical mast is trimmed for finest SWR on the desired frequency, however I discovered the impact minimal. You could possibly additionally “wind” a coil of some turns within the middle of the mast to decrease the profile of the antenna with out affecting feedpoint impedance drastically or efficiency an excessive amount of. I did that to make it brief sufficient to suit beneath my storage door header and observe no vital distinction in SWR or efficiency.
Be taught: The best way to make a 2 meter cell antenna
Efficiency:Mission completed. I can now get “into” the birds at low elevations. On it’s maiden journey out of the storage, I labored 4 stations (one was marine cell) on an 8 diploma AO-27 move. If I may hear the chook, I may work it (so long as a “large gun” station didn’t have the chook already captured). At excessive elevations I discovered I may run on low energy (about 3 Watts) and seize the chook with little ggstore.web antenna makes a pleasant companion to the 70 cm Handi-Tenna or can be utilized for any mounted, cell, or moveable service. For the reason that components are versatile 10 gauge wire, they are often readily folded and unfolded for backpacking.
Aricle by K5OE initially availbale a ggstore.web/k5oejerry/vhf_vert.htm
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