Need We Fuss About Exact Antenna Bearing for HF DX?

Do we need to set eaxct antenna bearing for HF DX? While working distant stations on HF bands do we need to be fussy about the exact beam headings and antenna bearing for HF DX? The short answer is NO… Yet, with the availability of various software utilities available to us both as standalone applications or online services, we often tend to get carried away. Several amateur radio operators, unfortunately, believe that unless their directional antennas like the Yagi are pointing precisely at the DX location they would not receive optimum signals. This is far from the truth. Let us quickly examine why. Of course, what we are discussing here is notwithstanding the fact that for VHF/UHF terrestrial radio contacts across several tens of kilometers one would need to beam quite accurately. Not only because the beam flare-out is narrow at short distances but also because much higher antenna gains on VHF and beyond produce far narrower beams… However, right now, we concern ourselves only with HF antennas for DX contacts. People at times ask me, What is your Grid-square?... Click Here to Read Full Article […]

Why might Antenna Height matter more than Gain

Does antenna height matter more than gain? Though it may seem to be paradoxical at first sight, the fact is that very often the antenna height above ground might matter more than its published gain when it comes to HF band antennas used for DX operation. Long-range DX contacts on HF bands typically require long skips on optimally selected frequency bands for best results. To achieve this objective, the radiation takeoff angle (TOA) has to be quite low. Especially, under low SSN conditions (as is prevalent at the time of writing this post), when the ionospheric plasma densities are low and the slab thickness is also less, the higher TOA signals might penetrate the ionosphere to be lost in outer space. Low TOA signals from the antenna provide us the best prospects. Does this mean that we need to search for some special kind of antenna with low TOA capability to deploy at our QTH? NO! We don’t… Every antenna can be installed in a manner so as to provide low TOA, however, the user must be aware of how... Click Here to Read Full Article […]

Challenges of working HF DX near Antipodes

Working HF DX stations located near Antipodes Working HF DX at the longest possible physical distance on earth is often referred to as working stations near Antipodes. These situations present several unique challenges that may never be observed while working regular DX at shorter distances that are not as far as the Antipode. These challenges manifest themselves while using directional beam antennas and may not be observed or appreciated by those of us who have omnidirectional antennas. The challenges of working stations at or near the antipodes are not only experienced by the station holding the frequency and calling CQ but also by those who are trying to work him. We cover the concept of Antipodes in an article under the section Geodesic for Terrestrial HF Radio. However, to recap for those who might be new to the term, an Antipode is a location that is at the opposite side of the globe from where a station might be located. Hence, every operator has a unique antipode based on his location. For the sake of simplicity, if we assume the... Click Here to Read Full Article […]

Radio Communication Architecture

PSK31 – A Robust QSO

PSK31 – for exciting HF band QRP PSK31 like most of the other narrow-band digital text communication modes requires very little TX power into a very modest antenna. PSK31 is also quite immune to co-channel interference by voice modulated radio-telephony signals due to the nature of the spectral distribution of human voice. Although PSK31 is a popular mode, many operators have failed to appreciate the inherent merits of this modulation mode and often resorted to incorrect modulation settings, higher than necessary TX power, or the use of large antennas which effectively increase the ERP beyond what is required for effective and sustainable PSK31 communication. This is a demonstration of typical QRP QSO using 5W (perhaps it was 3-4 W) into 1/4 λ vertical ground plane antennas used at both ends of the circuit. The distance was approximately 5800Km between a station with the QTH in Sweden and my QTH in New Delhi, India. The QSO was conducted on the 17m band at a little after 14:30 UTC. The PSK31 signal was not visible on the band-scope of my transceiver but... Click Here to Read Full Article […]

Communication Receivers

A Typical 40m HF Band Opening – A Graphical Rendition

40m HF band opening – Animated view Here is an animated graphical rendition of a typical 40m HF band opening transition scenario that I have modeled to provide a pictorial insight into the process. Any animated graphical rendering of HF band propagation opening as it gradually unfurls with the passage of time over the global canvas is a treat to watch. We all know that as a band opening begins to occur, the radio propagation prospects into distant land begin to unfold. This is a gradual process and is primarily dependent on the rotation of the earth on its axis leading to a change in illumination of the globe by solar radiation. As we daily progress through the diurnal (day/night) variation, we expect these changes to play out. On account of the above phenomena, the plasma density of the ionospheric layers above the earth also continuously alters their characteristics in terms of their charge densities, thickness, and height. During the night, the D-layer dissipates while the E-layer practically disappears due to excessive thinning of its plasma density. The F1 and... Click Here to Read Full Article […]

NEC Compliant Virtual antennas

State of Western Economy

State of Western Economy Starting in the year 2020, the economies of the world came under pressure, especially the western economy. This was caused due to various unforeseen global events that followed one after another. The turmoil started with the Covid-19 pandemic that hit the world. Two years later it was followed by the Ukraine-Russia conflict. The cascade effect of all these factors resulted in economic troubles. Although the entire world was adversely affected, greater disruptions were experienced by the western economy comprising mainly of the trans-Atlantic nations. These nations of the developed world mainly comprised of the USA, the UK, and the nations of Europe. The reason for the high magnitude of economic disruption experienced by the western economy was among other factors largely exacerbated due to carelessness and fiscal indiscipline. During the Covid-19 pandemic period, while a large number of bigger economies of the global south exercised adequate fiscal prudence, the nations of the collective west resorted to imprudent fiscal measures like large and indiscriminate stimulus cash distribution among its people. They were reckless in opting for huge... Click Here to Read Full Article […]

The Great Circle Map – GCM

The Great Circle Map – GCM We present an automatically rendered Great Circle Map – GCM based on your location derived from your Internet IP address. Therefore the Great Circle Map generated below should be accurate and relevant to your physical location (QTH). This map is an alternative to the Antenna Bearings Rectangular Map presented on another page of this website. This GCM projection provides a far more accurate alternative perspective. However, beware that if you are using a VPN to access this website, then the map rendering will be based on the IP location of your VPN and not your actual location. Your current location for which the Great Circle Map is rendered is given below… Latitude:        Longitude: When this webpage was loaded the original IP-derived Latitude and Longitude was used to render the Great Circle Map for the Grid Square location as a default. Normally, the map center accuracy should be more than adequate for HF radio DX communication purposes. However, if wish to generate GCM for any other Grid Square location, you may enter a properly... Click Here to Read Full Article […]