After researching 2 Meter Ground Plane antennas for my new ICOM IC-V82 Handheld I built one “hardwired” as we say in the software industry, meaning that it was soldered together permanently. The design was for approx. 146.00 MHz, i.e. the middle of the tuning range for the unit as I understand it.
Of course immediately after completing it I realized that it would be better to make it packable and to have several sets of elements so that it could be fine tuned at the upper or lower edge of that tuning range and even 6M and UHF frequencies as well. So I set to work by first examining each part and the connector options at each stage. I concluded that by utilizing a plate with the corners bent to the customary 45 deg. angle I could attach the various elements to that very conveniently. I also saw that the hex standoffs proliferatiing in my junk box would be very convenient attachment points.
This way the elements can be soldered into the socket end and the threaded stud could then be threaded into the plate or affixed with a nut on the other side. Regular solder can be used for steel, copper and brass or, better yet, for weatherability, silver solder can be used for all of those as well as stainless steel. Silver solder can be applied using a propane torch and is available at welding supply and some mega hardware stores now.
Note that the vertical element needs a hex connector to attach to which should be soldered to the center pin of the SO-239. The plate is attached to the SO-239 with four 1/8″ Pop Rivets and then the elements are attached to the plate.
Using Rhino, my design tool of choice, I produced the accompanying drawings. The critical part - the plate - is dimensioned but the tolerances are guidlines and are not as important as the bend angle of the radials, determined by the angle of the corners are bent to (45 deg.). The measurements for the elements can be found on multiple (and sometimes conflicting) web sites so I will leave the messy details of that to the wizards that know much more about tuning antennas than I do at the time. I merely offer a construction method that may have some value for a portable and collapsible antenna that can be broken down and put in a briefcase or other luggage suitable for travel, backpacking and, of course my favorite mode of transportation - sailing!!
Here are the dimensions for the MGPA antenna element lengths for the 146 MHz segment of the 2 meter band :
Vertical element - 19.3125″
Radials (4) - 20.1875″
Be sure to trim the elements AFTER they have been soldered into their respective sockets MINUS the threaded portion.
Rob Thomas, KC4NYK