VHF/UHF Omni Antenna for SOTA Use
For Summits On The Air (SOTA), I’ve been using just the VHF/UHF ham bands, with the 2m band being the most popular. For most activations, I use a 3-element Arrow II yagi antenna that has a gain of about 6 dBd. Sometimes that extra gain makes the difference between completing a contact or not.
But it is also handy to have an omnidirectional antenna that is easy to deploy. Sometimes I’d rather just call or monitor using an omni without having to point the antenna. “Easy and good enough” can be an effective strategy for SOTA.
A key advantage to an omnidirectional antenna is that it is always pointed in the right direction.
I usually carry one of the TWAYRDIO RH770 VHF/UHF antennas for use with my 2m/70cm handheld transceiver. Despite its low cost, I have found that its performance to be quite good. That antenna is offered with a variety of connectors, including a BNC.
This led me to the idea of putting together a simple antenna mount with a BNC on it, attach an RH770 antenna to it and support it using some kind of pole. I have several monopod devices (intended for use as a camera support) that use the standard 1/4-20 thread. I also have a trekking pole that has the same camera mounting thread. Another option is to use an actual camera tripod which is a bit bulky but may work for some SOTA activations.
After a short visit to the hardware store, I selected crossbar for mounting a light fixture that was about the right size and shape. I happened to have a bulkhead-mount BNC-to-BNC connector which I inserted into the large hole in the crossbar. That hole was not quite large enough for the connector, but a few minutes work with a round file solved that problem.
The crossbar was originally flat but I bent one one end of it 90 degrees, with the idea that this might offer other mounting configurations in the future. For example, I might be able to strap or tape the 90 degree angle member to a pole or support.
The other end of the crossbar has a large slot that accommodated the 1/4-20 mounting stud. Actually, the slot was not quite wide enough, so some addition work with a round file opened it up. I secured the 1/4-20 thread using a nylon wing nut.
I’ve used this setup on one SOTA activation and was pleased with the results. I carried the crossbar mount attached to the monopod in my pack. On the summit, I simply installed the RH770 antenna onto the top BNC and extended the monopod. On this summit, I found the perfect pile of rocks that made a good support for the monopod. Then I used a short length of RG-8X coax between the bottom BNC and the 2m/70cm transceiver.
Although my primary interest was with the 2 meter band, it was really convenient to have both 2m and 70cm on the same antenna. I am pleased with operation of the antenna and the ability to deploy it quickly. I expect to carry this on most of my SOTA activations.
73 Bob K0NR
The post VHF/UHF Omni Antenna for SOTA Use appeared first on The KØNR Radio Site.
I’ve done something similar, but a bit heavier, for non-backpacking setups.
Nagoya makes a ground plan bracket with an NMO mount. I unscrew my mobile antenna from the mag mount and screw it onto this. I’ll be doing this for Field Day.