I will be receiving a HF/VHF transverter for my BladeRF and would like to get my AM setup on the air. The Blade has enough power to send it around the office that is for sure, but what about getting it about a mile? 2 miles? I would like to keep the antenna as small as possible. I am focused on local coverage day and night.
I won't be using C-QUAM or DRM, just boring, mono AM with 11 kHz AF.
Some links to kits or preferablly pre-built/"IKEA" antennas would be nice.
Unfortunately there is no easy answer or small antenna at mediumwave that will perform well. At these wavelengths it all comes down to a very good earth ground system and as much wire as you can get into the air. The shorter the antenna becomes the narrower the bandwidth and harder it will be to tune for performance. There are a few options though and I would start with looking into Part 15 MW antenna plans which can be found all over the web. They will require a loading coil which can become complex since you are not only loading the shortened antenna but also transforming the impedance from 50ohms to high megaohms of a long wire.
If you are going for distance then nothing beats the inverted L for daytime and night coverage. If you have the power and want to shoot skip at night you will need a full dipole which at 1710kHz gets ridiculously large. With a 10 to 40' whip or pipe as your aerial and a good ground system you could get miles of coverage from as little as 10 watts of power during daytime and possibly night if conditions permit.
There are almost no pre-built antennas for these frequencies unless you buy a 160 meter ham antenna kit and then add on a little length to it or some loading to get it down from 1800kHz to 1660-1710kHz like you want. The other option is the 10' whips with base loading coil that are sold by part 15 kit suppliers but the range had with it may not be what you want, OTOH at least it will be cut and tuned upon ordering.
When it comes to such low frequencies the antenna is the most important factor of the whole transmitter setup. You can run the most powerful transmitter you can get your hands on but if it is going into a horrible radiator it will work only slightly better than a dummy load.
Hope this will not discourage you though. MW broadcasting is a lot of fun, but is a completely different animal than HF and above.
And, while this is an MW/AM focused topic, what about Hi-VHF? I am very aware of how the FM band works antenna-wise, but am not-so certain of the much higher frequencies, (namely 170-210MHz)?. Is this what I am looking for in that department?
And, while this is an MW/AM focused topic, what about Hi-VHF? I am very aware of how the FM band works antenna-wise, but am not-so certain of the much higher frequencies, (namely 170-210MHz)?. Is this what I am looking for in that department?
Sorry for the questions, thanks for the answers.
Your first link is broke.
As far as using specific frequencies like 170-210MHz you almost need an antenna designed for that range. Only way around that is using a wideband antenna that covers a large range of frequencies but it will be inefficient. You could use an antenna tuner also to cover that range but once again efficiency drops w/o a specifically cut antenna for that range. That may be fine for reception but for transmitting it is wasted effort. Just curious why do you want to use those frequencies anyways?
If I were you I would seriously consider learning a little bit about mediumwave antenna theory. Take a look at ham radio 160 meter antenna designs and plans since they are so close to the upper channels of the AM broadcast band that it would take little to convert those designs to work for pirating on AM. There really is no reason to buy an "ikea" type antenna lol, especially when you can just buy some wire, some egg insulators or even make your own out of PVC, use a sling shot to toss some thick fishing line over a tree and drag your wire up, try to get as high up as possible and run the vertical portion down to the tuner box. That method always wins. The inverted L or marconi T with a basic LC tuner is hands down the easiest and best method to use for a MW pirate.
You also need to keep in mind that vertical vs horizontal polarization can make a huge difference at low frequencies. Generally for daytime local coverage you NEED vertical polarization, or at least as high as you can get the wire in the air vertically. Nighttime on AM brings in skywave which can be a mix of vertical and horizontal propagation but for really reaching out at night while achieving the most flexability a horizontal dipole works wonders. The reason why is simple. Night prefers skip which is easily had by the projection angle of horizontal antennas whereas vertical antennas tend to project their signal out to the horizon. During the day the opposite happens which is why you DO NOT want to use a horizontal dipole. No point in projecting your signal to the clouds when there is no active ionosphere during the day, just wasted cloud burning power and is why you want to project it out to the horizon via "ground wave" during the day.
1) That specific frequency range is part of the Hi-VHF TV band. (7-13). My area is a "UHF island" and so that band is saturated with stations, mostly distant one. There are several things about where I live that make low-power UHF nearly impossible and/or impractical.
2) Broken link? Odd. It's a 160 meter grounded antenna. I have been reading through how to build some of these, it'll give me an excuse to get into the garage again lol. Appreciate the pointers.
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