Where should I put my first antenna, what type and why? - Page 1
Forum section: electronics / rf-microwave

author: rhb
author_rank: Super Contributor
timestamp: August 19, 2018, 12:44:19 am
content: I bought an FT-991A at Christmas and I'm trying to decide what sort of antenna to put up. I've still got to get relicensed, etc.Attached is a rough sketch of my house. The house, carport and deck have metal roofs. The shop is a 51' x 30' x 10' metal building. North is to the top. Southwest corner of the lot is grand piano size rocks all over the place. The lot slopes down about 10-15' from the rear of the deck. The end of a general aviation runway about is 1000' to the east and it's about 300' to the edge of the airport perimeter. The lot is heavily covered with tall trees, mostly pines. I've removed several and will probably remove a few more.Radials are out of the question because of the amount of rock. Current candidates are a vertical (e.g R9) 50' or so behind the house or an inverted V of some sort (e.g. dipole, G5RV) on the west side. There is an overhead power line in the front.A significant concern is the effect of all the metal roofing. I'm not going to be chasing DX or contesting. My primary interest is experimenting with QRP digital modes.I'd like to cover at least 80-10 m with the first antenna. I expect more to follow, but first I need one.My only station was an Ameco 6L6 on 40 m, a few xtals, a Panasonic RF-2200 and an inverted V made from blasting wire 40 years ago. I did keep a sched with a friend using the school club station which had a TS-520 on top of the engineering building.

author: xrunner
author_rank: Super Contributor
timestamp: August 19, 2018, 12:54:46 am
content: Well I use a fan dipole and have had great results. It's home made and very simple. It's simply several dipoles going to the same apex connector. One for each band but you can cover 40 and 15 with the same 40m dipole because 15 will tune on the 3rd harmonic.Check it out -http://www.m0pzt.com/fan-dipole/

author: hendorog
author_rank: Super Contributor
timestamp: August 19, 2018, 01:26:48 am
content: Any experienced ham I have ever asked that same question always says this :- "you have to go a long way to beat a dipole."I think the poor ground and lack of radials would rule out a vertical?Personally, I couldn't put up a dipole for a few reasons, so I made a delta loop instead. Triangle shaped, with the point upwards so only one high point is required and I could feed it at the bottom so it didn't look so obvious. It seemed to work fine, but of course I didn't have a dipole to compare it with! One of these days I'll get back into it again.Sounds like you have the room, and the trees, for a set of dipoles though so go for it!

author: vk6zgo
author_rank: Super Contributor
timestamp: August 19, 2018, 04:04:56 am
content: You seem to have enough room to fit in an 80m dipole, so you could go with that & feed it with an open wire feeder from an ATU.Alternately, you could use a trapped dipole, or a fan dipole.For a vertical, you could put a trapped vertical on your roof & have some elevated radials, or mount it on a shortish mast on the ground, again with elevated radials.Even a ground level one with radials lying on the surface should work.My suggestion is, for a first pass, slap up a dipole.When I finally got around to HF, the first thing I stuck up was a 20m dipole--- not very high, maybe 20ft above the ground---I called it my "glorified clothesline"!I had a lot of contacts with it, though!

author: rhb
author_rank: Super Contributor
timestamp: August 19, 2018, 11:51:36 am
content: A fan dipole was what I had been planning until I saw an ad for an R9 in QST. Not all that keen on the price though. My biggest concern with the dipole is being able to drive a ground rod near the mast if I orient the dipole N-S. But I might be able to do a sloper installation with the mast far enough back from the power lines.The only disadvantage of a dipole is the null N-S. An R9 fed 6' off the shop roof has been suggested. It's not clear I can go that high with the airstrip so close, but I'm going to go through the process and see.I plan to haul the antenna books off the shelf and read up on the topic. I've got the ARRL book, Kraus and a couple of others. I'm curious how you get a vertical to work without radials. though I suppose a vertical trapped dipole would work.I wanted to get some experienced opinions and this forum has some quite amazing members..

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: August 26, 2018, 12:36:35 pm
content: Though radiation patterns for dipoles show steep nulls, that's not how they radiate unless they are very high - particularly on 3.5 & 7 MHz. Such a dipole at ordinary heights is close to omnidirectional.A fan dipole with wires for 3.5, 7 & 14 MHz will give a good selection of bands and contacts.The previous suggestion about a tuned feeder dipole is also good, giving more band flexibility. But ideally you need a balanced antenna coupler (though that's fairly easy to build).Below is an example of a 7 MHz dipole that should be fairly efficient between about 5 and 21 MHz (radiation pattern tends to break up higher up).

author: rhb
author_rank: Super Contributor
timestamp: August 26, 2018, 12:54:30 pm
content: I've ordered a couple of recent books on antenna theory and modeling and plan to do a lengthy investigation modeling multiband HF dipoles. I made a more careful estimate of the trees in my yard and they are 40-50 ft tall, perhaps more. I'm contemplating hiring someone with climbing spikes (I can't find the ones Dad left me) to mount a pulley in one to allow using it as the central support for an inverted V with the wires tensioned by weights and pulleys to accommodate the swaying of the trees.So next up is to use a satellite image to locate the trees on the plat and see if that will work or if I need a mast.